WHAT AI STILL DOESN'T KNOW HOW TO DO

A few weeks ago a Google engineer got a lot of attention for a dramatic claim: He said that the company’s LaMDA system, an example of what’s known in artificial intelligence as a large language model, had become a sentient, intelligent being.

Large language models like LaMDA or San Francisco-based Open AI’s rival GPT-3 are remarkably good at generating coherent, convincing writing and conversations—convincing enough to fool the engineer. But they use a relatively simple technique to do it: The models see the first part of a text that someone has written and then try to predict which words are likely to come next. If a powerful computer does this billions of times with billions of texts generated by millions of people, the system can eventually produce a grammatical and plausible continuation to a new prompt or a question.

It’s natural to ask whether large language models like LaMDA (short for Language Model Dialogue Application) or GPT-3 are really smart—or just double-talk artists in the tradition of the great old comedian Prof. Irwin Corey, “The World’s Greatest Authority.” (Look up Corey’s routines of mock erudition to get the idea.) But I think that’s the wrong question. These models are neither truly intelligent agents nor deceptively dumb. Intelligence and agency are the wrong categories for understanding them.

Instead, these AI systems are what we might call cultural technologies, like writing, print, libraries, internet search engines or even language itself. They are new techniques for passing on information from one group of people to another. Asking whether GPT-3 or LaMDA is intelligent or knows about the world is like asking whether the University of California’s library is intelligent or whether a Google search “knows” the answer to your questions. But cultural technologies can be extremely powerful—for good or ill.

We humans are natural animists—we see agency everywhere, in rivers and trees and clouds and especially in machines, as anyone who has cursed a recalcitrant dishwasher can testify. So we readily imagine that the new machine-learning technology has created new agents, intelligent or dumb, helpful or (more often) malign. People have started talking about “an AI” rather than “AI”—as if it refers to a person rather than a computation.

Cultural technologies aren’t like intelligent humans, but they are essential for human intelligence. Many animals can transmit some information from one individual or one generation to another, but no animal does it as much as we do or accumulates as much information over time. To paraphrase Isaac Newton, every new human can see so far because they rest on the shoulders of those who came before them. New technologies that make cultural transmission easier and more effective have been among the greatest engines of human progress.

Language itself is the original cultural technology, allowing one hunter to tell another where to find the game, or a grandmother to pass on a hard-won cooking technique to her granddaughter. Writing transformed culture once again; we could access the wisdom of grannies from hundreds of years earlier and hundreds of miles away. The printing press helped enable both the industrial revolution and the rise of liberal democracy. Libraries, and their indexes and catalogs, were essential for the development of science and scholarship. Internet search engines have made it even easier to find information.

Like these earlier technologies, large language models help access and summarize the billions of sentences that other people have written and use them to create new sentences. Other systems like OpenAI’s DALL-E 2, which just produced a cover illustration for Cosmopolitan magazine, do this with the billions of images we create, too. The history of cultural technology is that we have become able to access the knowledge of more and more other minds, across greater gulfs of space and time, more and more easily, and the new AI systems are the latest step in that process.

But if so much of what we know comes from other people’s language, doesn’t something like GPT-3 really have all the intelligence it needs? Don’t those billions of words encapsulate all human knowledge? What’s missing?

Cultural transmission has two sides—imitation and innovation. Each generation can use imitation to take advantage of the discoveries of previous ones, and large language models are terrific imitators. But there would be no point to imitation if each generation didn’t also innovate. We go beyond the words of others and the wisdom of the past to observe the world anew and make new discoveries about it. And that is where even very young humans beat current AI.

In what’s known as the classic “Turing test,” Alan Turing in 1950 suggested that if you couldn’t tell the difference in a typed conversation between a person and a computer, the computer might qualify as intelligent. Large language models are getting close. But Turing also proposed a more stringent test: For true intelligence, a computer should not only be able to talk about the world like a human adult—it should be able to learn about the world like a human child.

In my lab we created a new online environment to implement this second Turing test—an equal playing field for children and AI systems. We showed 4-year-olds on-screen machines that would light up when you put some combinations of virtual blocks on them but not others; different machines worked in different ways. The children had to figure out how the machines worked and say what to do to make them light up. The 4-year-olds experimented, and after a few trials they got the right answer. Then we gave state-of-the-art AI systems, including GPT-3 and other large language models, the same problem. The language models got a script that described each event the children saw and then we asked them to answer the same questions we asked the kids.

We thought the AI systems might be able to extract the right answer to this simple problem from all those billions of earlier words. But nobody in those giant text databases had seen our virtual colored-block machines before. In fact, GPT-3 bombed. Some other recent experiments had similar results. GPT-3, for all its articulate speech, can’t seem to solve cause-and-effect problems.

If you want to solve a new problem, googling it or going to the library may be a first step. But ultimately you have to experiment, the way the children did. GPT-3 can tell you what the most likely outcome of a story will be. But innovation, even for 4-year-olds, depends on the surprising and unexpected—on discovering unlikely outcomes, not predictable ones.

Does all of this mean we don’t have to worry about AI becoming sentient? I think worries about super-intelligent and malign artificial agents, modern golems, are, at the least, overblown. But cultural technologies change the world more than individual agents do, and there’s no guarantee that change will be for the good.

Language allows us to lie, seduce and intimidate others as much as it allows us to communicate accurately and discover the truth. Socrates famously thought that writing was a really bad idea. You couldn’t have the Socratic dialogues in writing that you could in speech, he said, and people might believe things were true just because they were written down—and he was right. Technological innovations let Benjamin Franklin print inexpensive pamphlets that spread the word about democracy and supported the best aspects of the American Revolution. But as the historian Robert Darnton showed, the same technology also released a flood of libel and obscenity and contributed to the worst aspects of the French Revolution.

People can be biased, gullible, racist, sexist and irrational. So summaries of what people who preceded us have thought, in an “old wives’ tale,” a library or the internet, inherit all of those flaws. And that can clearly be true for large language models, too.

Every past cultural technology has required new norms, rules, laws and institutions to make sure that the good outweighs the ill, from shaming liars and honoring truth-tellers to inventing fact-checkers, librarians, libel laws and privacy regulations. LaMDA and GPT-3 aren’t people in disguise. But the real people who use them need to go beyond the conventions of the past and create innovative institutions that can be as powerful as the technologies themselves.

THE MANY MINDS OF THE OCTOPUS

Cephalopods are having a moment. An octopus stars in a documentary nominated for an Academy Award (“My Octopus Teacher”). Octos, as scuba-diving philosopher Peter Godfrey Smith calls them, also play a leading role in his marvelous new book “Metazoa,” alongside a supporting cast of corals, sponges, sharks and crabs. (I like Mr. Godfrey-Smith’s plural, which avoids the tiresome debate over Latin and Greek endings).

Part of the allure of the octos is that they are both very smart, probably the smartest of invertebrates, and extremely weird. The intelligence and weirdness may be connected and can perhaps teach us something about those other intelligent, weird animals we call homo sapiens

Smart birds and mammals tend to have long lives and an especially long, protected childhood. Crows and chimps put a lot of work into taking care of their helpless babies. But, sadly and strangely, the intelligent octos only live for a year and don’t really have a childhood at all. They die soon after reproducing and, like the spider heroine of “Charlotte’s Web,” don’t even live to see the next generation grow up, let alone to look after them.

Smart birds and mammals also keep their neurons in one place—their brains. But octos split them up. They have over 500 million neurons altogether, about as many as dogs. But there are as many neurons altogether in their eight arms as in their heads. The arms seem able to act as independent agents, waving and wandering, exploring and sensing the world around them—even reaching out to the occasional diving philosopher or filmmaker. Mr. Godfrey-Smith’s book has a fascinating discussion of how it must feel to have this sort of split consciousness, nine selves all inhabiting the same body.

I think there might be a link between these two strange facts of octopus life. I’ve previously argued that childhood and intelligence are correlated because of what computer scientists call the “explore-exploit” trade-off: It’s very difficult to design a single system that’s curious and imaginative—that is, good at exploring—and at the same time, efficient and effective—or good at exploiting. Childhood gives animals a chance to explore and learn first; then when they grow up, they can exploit what they’ve learned to get things done.

Childhood isn’t the only way to solve the explore-exploit problem. Bees, who, like octos, are smart but short-lived, use a division of labor, with scouts who explore and workers who exploit. But octos are much more solitary than bees.

The evolutionary path that led to the octos diverged from the human one hundreds of millions of years ago, before the first animal crawled out of the sea. They must have developed a different way to solve the explore-exploit dilemma. Perhaps their eight-plus-one brains serve the same function as the different phases of human development, or the different varieties of bees. The playful, exploratory arms can come under the control of the brain when it’s time to act—to mate, feed or flee. The head might feel kind of like a preschool teacher on an outing, trying to corral eight wandering children and to get them to their destination. (Imagine if your arms were as contrary as your 2-year-old!)

We grown-up humans may not be so different. Human adults are “neotenous apes,” which means we retain more childhood characteristics than our primate relatives do. We keep our brains in our heads, but neuroscience and everyday experience suggest that we too have divided selves. My grown-up, efficient prefrontal cortex keeps my wandering, exploratory inner child in line. Or tries to, anyway.

THE POWER OF THE WANDERING MIND

There’s only one way to write: Just do it. But there seem to be a million ways not to write. I sit down to work on my column, write a sentence and—ping!—there’s a text with a video of my new baby grandson. One more sentence and I start ruminating about the latest virus variant, triggering a bout of obsessive Covid worry. Cut it out! I tell myself, and write one more sentence, and then I’m staring blankly out the window, my mind wandering: What was it with that weird movie last night? Should I make chicken pilaf or lamb tagine for dinner?

These different kinds of thinking are the subject of a paper I co-authored recently in the journal PNAS, which has an interesting back story. Zachary Irving is a brilliant young philosopher now at the University of Virginia, well-trained—as philosophers have to be—at thinking about thinking. He is especially interested in the kind of unconstrained thought we have when our mind wanders. Is mind-wandering really distinct from other kinds of thought, like simple distraction or obsessive rumination? And why do we do it so much?

Young children daydream a lot, so Zach came to visit my lab at Berkeley, where we study children’s thinking. Neuroscience has mainly focused on goal-directed, task-oriented thinking, but what is your brain doing when your mind wanders? To answer that question, we worked with Julia Kam, now at the University of Calgary, and Robert Knight to design an experiment that involved giving 45 people a tedious but demanding task: pressing an arrow when a cue appeared on the screen. The participants did this more than 800 times for 40 minutes, and at random intervals we asked them to report what they were thinking. Were they thinking about the task or something else? Were they obsessing about a single topic or were their minds freely wandering?

Meanwhile, the participants’ brain waves were being measured with electroencephalography or EEG. The study found that different types of thinking correspond to different brain wave patterns. Like earlier researchers, we found that brain waves are different when you pay attention to a task and when you get distracted. But we found that different types of distraction also have different brain signatures. We compared what happens when your mind is captured by an internal obsession like worrying about Covid, and what happens when it wanders freely.

When your mind wanders there’s a distinctive increase in a particular measure called frontal alpha power, which captures a particular type of wave coming from the frontal lobe of the brain. That’s especially interesting because the same brain waves are associated with creative thinking. People show more frontal alpha power when they are solving a task that requires creativity, and more creative people show more of this kind of activation than less creative ones. One study even showed that stimulating frontal alpha led to better performance on a creativity task.

There was also more variability in those frontal alpha waves when thoughts wandered than when they were focused. The brain patterns went up and down more during those thoughts, just like the thoughts themselves.

We puritanically tend to value task-related thinking above everything else. But these results suggest that simply letting your mind wander, the way kids do, has merits too. My wandering mind made this column harder to write. But maybe it came out better as a result.

OUR SENSE OF FAIRNESS IS BEYOND POLITICS

What do the haves owe to the have-nots? Should a society redistribute resources from some people to others? These questions are central to the economic policy differences between left and right. The opposing views might seem completely irreconcilable. But a new paper in the journal Cognition suggests that people of all political stripes have surprisingly similar views about redistribution, at least in the abstract.

Daniel Nettle at Newcastle University and Rebecca Saxe at MIT presented 2,400 people in the U.K. with stories about how an imaginary village could divvy up the food people grew in their gardens. A simple graphic allowed the participants to say how much food they thought should go from villagers who had more to those who had less.

The scenario allowed the researchers to systematically vary aspects of the problem. They looked at four factors. How much did the garden yields depend on luck? In some versions of the scenario, the weather had a big influence on how much food each villager produced; in others, luck was less important. How homogenous was the village? In some versions the villagers had very similar “beliefs, customs and appearance,” in others they were “rather different.” Were the villagers at peace with other villages or under attack? And was food abundant or scarce in general?

The participants also reported how far to the right or left their politics were, and across the spectrum the results were very consistent. Everybody thought there should be some redistribution of food—there weren’t any real Scrooges. People of all political persuasions thought there should be more redistribution when luck played a larger role, when the village was more homogenous, when the village was under attack and when resources were abundant. Political views did play a small role in people’s judgments: Those on the right were slightly less likely to redistribute than those on the left. But politics was much less important than the particular story of that village.

You could think of these experiments as an empirical version of the philosopher John Rawls’s famous thought experiment about “the veil of ignorance.” Rawls thought that we could agree in principle about what kind of economic system is fair if we had no idea what our particular role in that system would be—if we didn’t know whether we would be born rich or poor, smart or dull, American or Chinese. The imaginary villages suggest that, at least for a large selection of 21st century Britons, Rawls was right: People do have similar intuitions about what’s fair.

The most interesting point, which has been reflected in other psychological studies as well, is that people’s views on fairness depend more on the factual details of particular situations than on their partisan positions. That’s true even on a topic as obviously political and controversial as redistribution.

Of course, in these studies participants were explicitly told the facts about each village. In real life, it can be hard to know whether someone is lucky or hard-working, or what common features make people part of the same community. And sometimes we might want to argue about these intuitions themselves: Is it really better to redistribute more when resources are more abundant, or when people are more similar? But first, we have to do the hard work to make sure people share the same information and have access to the same truth. Then, at least sometimes, reason and persuasion can prevail.

2020

DESPITE COVID-19, OLDER PEOPLE ARE STILL HAPPIER

As we get older we get slower, creakier and stiffer—and a lot happier. This might seem surprising, but it’s one of the most robust results in psychology, and it’s true regardless of income, class or culture. In our 70s and 80s, we are happier than when we were strong and beautiful 20-year-olds.

There are a couple of theories about why this is. We may get better at avoiding stressful situations—we figure out how to dodge that tense work meeting or family squabble. Or there may be something about aging that makes it easier to tolerate stress, even when we can’t avoid it.

The Covid-19 pandemic is a test case for this principle. It’s a terrible threat that is stressful for everyone, but it’s especially dangerous for older people, who are far more likely to die from the disease. Does the association between aging and happiness still hold?

Apparently the answer is yes. According to a new study by Laura Carstensen and colleagues at Stanford University, older people are happier even during the pandemic.

Think back to the first Covid surge in North America last April. The full awfulness of the plague had become apparent, and the uncertainty just made it scarier. We were all anxiously washing our groceries and trying to stay home. That month, the researchers surveyed a representative sample of 974 people from 18 to 74 years old, asking how often and how intensely they had felt 29 different positive and negative emotions in the past week. How often had they been calm or peaceful, concerned or anxious? The participants also reported how much they felt personally at risk from the virus and how risky they thought it was for people in general.

Older people rationally and accurately said that they were more at risk than younger ones. But surprisingly, they also reported experiencing more positive emotions and fewer negative ones than younger people did. Even when the researchers controlled for other factors like income and personality, older people were still happier. In particular, they were more calm, quiet and appreciative, and less concerned and anxious.

The results suggest that older people aren’t happier just because they’re better at avoiding stress—Covid-19 is stressful for everyone. But it’s not so clear just what is responsible. Prof. Carstensen suggests that when there is less time ahead of us, we focus more on the positive parts of the time we have left. As we sometimes sigh when we dodge a conflict, “life is too short”—and it gets shorter as we get older.

Another possibility is that in later life we play a different social role. Humans live much longer than our closest primate relatives: Chimps die when they are around 50, but even in hunter-gatherer cultures humans live into their 70s. Those bonus years are especially puzzling because women, at least, stop reproducing after menopause.

I think those later years may be adapted to allow us to care and teach. Instead of striving to get mates and resources and a place in the pecking order, older people can focus on helping the next generation. We take care of others and pass on our resources, skills and knowledge, instead of working for our own success. As a result, we may be released from the intense emotions and motivations that drive us in our earlier lives. Age grants us an equanimity that even Covid-19 can’t entirely conquer.

WHAT AI CAN LEARN FROM PARENTS

To train an artificial intelligence using “machine learning,” you give it a goal, such as getting a high score in a videogame or picking out all the photos in a set that have a cat in them. But you don’t actually tell the AI how to achieve the goal. You just give it lots of examples of success and failure, and it figures out how to solve the problem itself.

But imagine this sorcerers’ apprentice scenario, first proposed by the philosopher Nick Bostrom. One day in the future, someone builds an advanced AI very much smarter than any current system and gives it the goal of making paper-clips. The AI, faithfully following instructions, takes over the world’s machines and starts to demolish everything from pots and pans to cars and skyscrapers. so it can melt down the raw material and turn it into paper clips. The AI is doing what it thinks its creator wanted, but it gets things disastrously wrong.

On social media, we may face a version of this apocalypse already. Instead of maximizing paper clips, Facebook and Twitter maximize clicks, by showing us things that their algorithms think we will be interested in. It seems like an innocent goal, but the problem is that outrage and fear are always more interesting, or at least more clickable, than sober information.

The gap between what we actually want and what an AI thinks we want is called the alignment problem, since we have to align the machine’s function with our own goals. A great deal of research in AI safety and ethics is devoted to trying to solve it. In his fascinating new book “The Alignment Problem,” writer and programmer Brian Christian describes a lot of this research, but he also suggests an interesting and unexpected place to look for solutions: parenting.

After all, parents know a lot about dealing with super-intelligent systems and trying to give them the right values and goals. Often, that means making children’s priorities align with ours, whether that means convincing a toddler to take a nap or teaching a teenager to stay away from drugs. A lot of the work of being a parent, or a caregiver or teacher more generally, is about solving the alignment problem.

But when it comes to children, there’s an added twist. Computer programmers hope to make an AI that will to do exactly what they want. But as parents, we don’t want our children to have exactly the same preferences and accomplishments that we do. We want them to become autonomous, with their own goals and values, which may turn out to be better than our own.

One possible solution to the alignment problem is to design AIs that are more skilled at divining what humans really want, even when we don’t quite know ourselves. This would be a sort of Stepford Wife AI, slavishly devoted to serving us.

But it might be better to think of creating AIs as more like parenting, as the science fiction writer Ted Chiang does in his beautiful story “The Lifecycle of Software Objects.” The story imagines a future where people adopt and train childlike AIs called “digients” as a kind of game. Soon, though, the “parents” come to love the artificial children they care for, and ultimately they face the same dilemmas of independence and care that parents of human children do. If we ever do create truly human-level intelligence in machines, we may need to give them mothers.

INNOVATION RELIES ON IMITATION

Where do good ideas come from? How can we find new solutions to difficult, urgent problems, from the pandemic to the climate crisis? A zillion consulting firms and business books may claim that they know the answer, but there’s been remarkably little empirical data.

Elena Miu and Luke Rendell at the University of St. Andrews, like many other biologists, argue that “cultural evolution” is one of the secrets. Human beings gradually accumulate new ideas and solutions. New technologies, from stone axes to smartphones, almost always come from the interaction of many individual problem-solvers rather than a lone genius. But how could such a complicated process be studied?

In two studies, reported in the journals Nature Communications in 2018 and Science Advances in 2020, Prof. Miu and colleagues cleverly took advantage of data from coding competitions. From 1998 to 2012, Mathworks Software held a series of 19 public competitions to find the best coding solutions to computer-science problems. Nearly 2,000 participants submitted more than 45,000 entries. There was no single correct solution to the problems; instead, the contestants tried to produce code that would be simpler and work better, with judges assigning a score to each entry.

All the solutions and scores were open for public viewing, so new contestants could see how earlier ones approached the problems. Researchers were able to measure how similar each new solution was to earlier attempts, allowing them to witness cultural evolution in action.

One of the central challenges of cultural evolution is how to balance imitation and innovation. Imitation lets us take advantage of all the ideas that our ancestors have discovered before us. But innovation is also crucial, since if everybody just copied everybody else, we’d never make any progress.

Prof. Miu and her colleagues found that the coding contestants fell into three groups. There were “copiers” who consistently imitated the successful solutions, making only the smallest changes. There were also “mavericks” who didn’t copy the entries that were already out there but tried something new, more like the stereotypical lone genius. And then there were “pragmatists” who flexibly switched back and forth between copying and innovating.

The researchers found that pragmatists were by far the most likely to receive high scores. They built on the work that had already been done, but unlike the simple copiers, they substantially altered and improved the code, too.

The researchers found similar trade-offs when they focused on individual entries instead of on contestants, who could submit more than one solution to a problem. About 75% of entries were “tweaks,” making small changes to solutions that other people had already suggested. But there were also “leaps,” solutions that were very different from the ones already out there.

Overall, the leaps were much less likely to be successful than the tweaks; most of them went nowhere. But when leaps were successful, they led to much better solutions and opened up whole new sets of ideas. In fact, there was a consistent pattern: Someone would introduce a fabulous new leap and then the next generation of contestants would refine it with tweaks.

What can these studies tell us about how to solve real-life problems? Diversity is key. Rather than the lone genius, it’s the combination of different kinds of knowledge and temperament, humble tweaks and bold leaps, that produces new solutions.

A GOOD LIFE DOESN'T MEAN AN EASY ONE

What makes a good life? Philosophers have offered two classic answers to the question, captured by different Greek words for happiness, hedonia and eudaimonia. A hedonic life is free from pain and full of everyday pleasure—calm, safe and serene. A eudaemonic life is a virtuous and purposeful one, full of meaning.

But in a new study, philosopher Lorraine Besser of Middlebury College and psychologist Shigehiro Oishi of the University of Virginia argue that there is a third important element of a good life, which they call “psychological richness.” And they show that ordinary people around the world think so, too.

According to this view, a good life is one that is interesting, varied and surprising—even if some of those surprises aren’t necessarily pleasant ones. In fact, the things that make a life psychologically rich may actually make it less happy in the ordinary sense.

After all, to put it bluntly, a happy life can also be boring. Adventures, explorations and crises may be painful, but at least they’re interesting. A psychologically rich life may be less eudaemonic, too. Those unexpected turns may lead you to stray from your original purpose and act in ways that are less than virtuous.

Profs. Besser and Oishi make the case for a psychologically rich life in a paper that has just appeared in the journal Philosophical Psychology. But is this a life that most people would actually want, or is it just for the sort of people who write philosophy articles?

To find out, the authors and their colleagues did an extensive study involving more than 3,000 people in nine countries, recently published in the Journal of Affective Science. The researchers gave participants a list of 15 descriptive words such as “pleasant,” “meaningful” and “interesting,” and asked which best described a good life.

When they analyzed the responses, Profs. Besser and Oishi found that people do indeed think that a happy and meaningful life is a good life. But they also think a psychologically rich life is important. In fact, across different cultures, about 10-15% of people said that if they were forced to choose, they would go for a psychologically rich life over a happy or meaningful one.

In a second experiment the researchers posed the question a different way. Instead of asking people what kind of life they would choose, they asked what people regretted about the life they had actually led. Did they regret decisions that made their lives less happy or less meaningful? Or did they regret passing up a chance for interesting and surprising experiences? If they could undo one decision, what would it be? When people thought about their regrets they were even more likely to value psychological richness—about 30% of people, for example, in both the U.S. and South Korea.

The desire for a psychologically rich life may go beyond just avoiding boredom. After all, the unexpected, even the tragic, can have a transformative power that goes beyond the hedonic or eudaemonic. As a great Leonard Cohen song says, it’s the cracks that let the light come in.

LEARNING WITHOUT A BRAIN

It might seem obvious that you need a brain to be intelligent, but a new area of research called “basal cognition” explores whether there are kinds of intelligence that don’t require neurons and synapses. Some of the research was reported in a special issue of the Philosophical Transactions of the Royal Society last year. These studies may help to answer deep questions about the nature and evolution of intelligence, but the experiments are also just plain fascinating, with truly weird creatures and even weirder results.

Slime molds, for example, are very large single-celled organisms that can agglomerate into masses, creeping across the forest floor and feeding on decaying plants. (One type is called dog vomit slime mold, which gives you an idea of what they look like.) They can also retreat into a sort of freeze-dried capsule form, losing much of their protein and DNA in the process, and stay that way for months. But just add water and the reconstituted slime mold is good as new.

They are also fussy eaters. If you put them down on top of their favorite meal of agar and Quaker oats and add salt or quinine to one part of it, they’ll avoid that part, at least at first. The biologists Aurele Bousard and Audrey Dussutour at the University of Toulouse and colleagues used this fact to show that slime molds can learn in a simple way called habituation. If the only way to get the oats is to eat the salt too, the molds eventually get used to it and stop objecting. Remarkably, this information somehow persists for up to a month, even through their period of dessicated hibernation.

Flatworms are equally weird. Cut one into a hundred pieces and each piece will regenerate into a perfect new worm. (A slime mold-flatworm alliance against the humans would make a great horror movie). But how do the cells in the severed flatworm fragment know how to grow into a head and a tail?

Santosh Manicka and Michael Levin of Tufts University argue in the special issue that regeneration involves a kind of cognition. The process is remarkably robust: You can move the cells that usually make a head to the tail location, and they will somehow figure out how to make a tail instead. The researchers argue that this ability to take multiple paths to achieve the same goal requires a kind of intelligence.

Regeneration involves the standard mechanisms that allow the DNA in a cell to manufacture proteins. But Dr. Levin and his colleagues have shown that flatworm cells also communicate information through electricity, signaling to other nearby cells in much the way that neurons do. In experiments that would make Dr. Frankenstein proud, the researchers altered those electrical signals to produce a worm that consistently regenerates with two heads, or even one that grows the head of another related species of flatworm.

This research has some practical implications: It would be great if human accident victims could grow back their limbs as easily as flatworms do. But the studies also speak to a profound biological and philosophical conundrum. Where do cognition and intelligence come from? How could natural selection turn single-celled amoebas into homo sapiens? Dr. Levin thinks that the electrical communications that help flatworms regenerate might have evolved into the subtler mechanisms of brain communication. Those creepy slime molds and flatworms might help to explain how humans got smart.

WHY ELDERS ARE INDISPENSABLE FOR ALL OF US

Like children, older people need special care. The current crisis has made this vivid. Millions of people have transformed their lives—staying indoors, wearing masks, practicing social distancing—to protect their vulnerable parents and grandparents, as well as other elders they may never even see.

But this raises a puzzling scientific paradox. We know that human beings are shaped by the forces of evolution and natural selection. So why did we evolve to be vulnerable for such a long stretch of our lives? And why do strong, able humans in the prime of life put so much time and energy into caring for those who are no longer so productive? Chimpanzees rarely live past 50 and there is no chimp equivalent of menopause. But even in hunter-gatherer cultures without modern medicine, if you make it past childhood you may well live into your 70s. Human old age, cognition and culture evolved together.

A new special issue of the Philosophical Transactions of the Royal Society devoted to “Life History and Learning,” which I coedited, brings together psychologists, anthropologists and evolutionary biologists to try to answer these questions.

Humans have always been “extractive foragers,” using complicated techniques like hunting and fishing that let us find extra calories in almost any environment. Our big brains make this possible, but we need culture and teaching to allow us to develop complex skills over many generations.

In the special issue, Michael Gurven of the University of California at Santa Barbara and colleagues argue that older people may have a special place in that process. Many foraging skills require years of practice: Hunters don’t reach their peak until they are in their 30s.

But it’s hard to practice a skill and teach it to someone else at the same time. (Sunday pancakes take twice as long when the kids help.) Prof. Gurven and his team found that, mathematically, the best evolutionary strategy for developing many complex skills was to have the old teach the young. That way the peak, prime-of-life performers can concentrate on getting things done, while young learners are matched with older, more knowledgeable but less productive teachers.

The researchers analyzed more than 20,000 observations collected from 40 different locations, and found this pattern in many different hunting and gathering cultures. Children were most likely to learn either from other, older children or from elders. The grandparents weren’t as strong or effective providers as the 30-year-olds, but they were most likely to be teachers.

This may explain why humans evolved to have a long old age: The advantages of teaching selected for those extra years of human life. From an evolutionary perspective, caring for vulnerable humans at either end of life lets all humans flourish.

The pandemic has made us realize both the importance and the difficulty of this kind of care. In the richest society in history, the job of caring for the old and the young involves little money and less status. Elders are often isolated. Perhaps after the pandemic we will appreciate better the profound connection between brilliant, fragile young learners and wise, vulnerable old teachers, and bring the grandchildren and grandparents back together again.

HOW HUMANS EVOLVED TO CARE FOR OTHERS

The last few weeks have seen extraordinary displays of altruism. Ordinary people have transformed their lives—partly to protect themselves and the people they love from the Covid-19 pandemic, but also to help other people they don’t even know. But where does altruism come from? How could evolution by natural selection produce creatures who sacrifice themselves for others?

In her 2019 book “Conscience,” the philosopher Patricia Churchland argues that altruism has its roots in our mammalian ancestry. The primordial example of an altruistic emotion is the love that mothers feel toward their babies. Helpless baby mammals require special care from their nursing mothers, and emotional attachment guarantees this care.

Those emotions and motivations are associated with a distinctive pattern of brain activations, hormones and genes. Twenty years ago, neuroscientists discovered that the same brain mechanisms that accompany mother love also operate when mammals care about their mates. Only about 5% of mammal species are “pair-bonded,” with mates who act like partners—seeking out each other’s company, raising babies together and actively helping each other. It turns out that those pair-bonded species, like prairie voles, have co-opted the biology that underpins mother love.

In turn, Prof. Churchland argues, those biological mechanisms could underpin broader altruistic cooperation in species with larger interdependent social groups, like wolves and monkeys. When the members of a species have to hunt, forage or—most important—raise their young together, they start caring about each other too. In humans, who have an exceptionally long childhood, that love and care extended not only to mates but to “alloparents”—unrelated people who help take care of children.

In a 2017 paper in the journal Cognition, researchers Rachel Magid and Laura Schulz of M.I.T. showed that when we care for another person in this altruistic way, we extend our own needs to include theirs, in a process they describe as ”moral alchemy.” A caregiver—whether human or vole, mother or father or grandparent or alloparent—doesn’t just do what’s good for the baby because of an abstract obligation or an implicit contract. It’s because the baby’s needs have become as important to them as their own.

Our long, helpless childhood gives humans a great advantage in return: It gives us to time to learn, imagine and invent. We combine these intellectual abilities with the primordial emotions of care. We can imagine new technologies and use them for altruistic purposes, from medical discoveries about how to fight viruses to Zoom sessions that let me tell my grandchildren I love them.

But the largest and most profound imaginative human leap comes when we take those altruistic emotions and apply them beyond the family and village, to strangers, foreigners and the world at large. Prof. Churchland argues that we don’t begin with universally applicable rational principles—Kant’s categorical imperative or the greatest good for the greatest number—and then apply them to particular cases. Instead, we begin with the close and the personal and expand those attachments to a wider circle.

In evolutionary history, the extension of altruism from mothers and babies to larger groups allowed humans to cooperate and thrive. Now our lives are entangled with those of everyone else on the planet, and our survival depends on widening the circle even more.

DETECTING FAKE NEWS TAKES TIME

A few weeks ago, I took part in a free-wheeling annual gathering of social scientists from the academic and tech worlds. The psychologists and political scientists, data analysts and sociologists at Social Science Foo Camp, held in Menlo Park, Calif., were preoccupied with one problem in particular: With an election looming, what can we do about the spread of misinformation and fake news, especially on social media?

Fact-checking all the billions of stories on social media is obviously impractical. It may not be effective either. Earlier studies have shown an ”illusory truth” effect: Repeating a story, even if you say that it’s false, may actually make people more likely to remember it as true. Maybe, in our highly polarized world, they can’t even tell the difference; all that matters is whether the story supports your politics.

But new research contradicts this pessimistic picture. David Rand of MIT and Gordon Pennycook of the University of Regina have suggested that “cognitive laziness” may be a bigger problem than bias. It’s not that people can’t tell or don’t care whether a story is true; it’s just that they don’t put in the effort to find out.

A new study in the Journal of Experimental Psychology by Profs. Rand and Pennycook, with Bence Bago of the University of Toulouse, shows that if you give people time to think, they do better at judging whether news stories on social media are true or false.

The researchers showed more than 1,000 people examples of true and false headlines that had actually appeared online—real fake news, as it were. Some headlines were slanted toward Republicans, like “Obama was going to Castro’s funeral until Trump told him this,” while others were slanted toward Democrats, like “Gorsuch started ‘fascism forever’ club at elite prep school.”

The researchers asked participants to judge whether the headlines were accurate. One group was allowed to take as much time as they wanted to make a judgment, while another group had to decide in seven seconds, while they were also trying to remember a pattern of dots shown on the screen. Then they had a chance to think it over and try again. The participants also filled out a questionnaire about their political views.

As you might expect, people were somewhat more likely to believe fake news that fit their ideological leanings. But regardless of their politics, people were more likely to spot the difference between real and fake news when they had time to think than when they had to decide quickly.

Of course, when we browse Twitter or Facebook, we are more likely to be rushed and distracted than patiently reflective. Lots of items are pouring quickly through our feeds, and nobody is asking us to pause and think about whether those items are accurate.

But it would be relatively easy for the platforms to slow us down a little and make us more thoughtful. For example, you could simply ask people to rate how accurate a story is before they share it. In preliminary, still unpublished work, Profs. Rand and Pennycook found that asking people to judge the accuracy of one story on Twitter made them less likely to share others that were inaccurate.

Cognitive science tells us that people are stupider than we think in some ways and smarter in others. The challenge is to design media that support our cognitive strengths instead of exploiting our weaknesses.

HUMANS EVOLVED TO LOVE BABY YODA

Like many people with children or grandchildren, I spent December watching the new Star Wars TV series “The Mandalorian.” Across America, the show led to a remarkable Christmas truce among bitterly competing factions. Rural or urban, Democrat or Republican, we all love Baby Yoda.

In case you spent the last month in a monastic retreat, Baby Yoda is the weird but irresistibly adorable creature who is the heart of the series. (He isn’t actually Yoda but a baby of the same species.) The Mandalorian, a ferocious bounty-hunter in a metal helmet, takes on the job of hunting down Baby Yoda but ends up rescuing and caring for him instead. This means finding snacks and sitters and keeping the baby from playing with the knob on the starship gear shift.

Why do the Mandalorian and the whole internet love Baby Yoda so much? The answer may tell us something profound about human evolution.

Humans have a particularly long and helpless infancy. Our babies depend on older caregivers for twice as long as chimp babies do. As a result, we need more varied caregiving. Chimp mothers look after their babies by themselves, but as the great anthropologist Sarah Hrdy pointed out in her 2009 book “Mothers and Others,” human mothers have always been assisted by fathers, grandparents and “alloparents”—people who look after other folks’ children. No other animal has so many different kinds of caregivers.

Those caregivers are what anthropologists call “facultative,” meaning that they only provide care in certain circumstances and not others. Once they are committed to a baby, however, they may be just as devoted and effective as biological mothers. The key factor seems to be the very act of caregiving itself. We don’t take care of babies because we love them; instead, like the Mandalorian, we love babies once we start taking care of them.

In a new paper forthcoming in the Philosophical Transactions of the Royal Society, Dr. Hrdy and Judith Burkart argue that this led to the evolution of special social adaptations in human babies, since they have to actively persuade all those facultative caregivers to love them. Studies show that babies have physical features that automatically attract care—those adorable, “awww”-inducing big eyes and heads and fat cheeks and little noses, all of which are exaggerated in Baby Yoda. Drs. Hrdy and Burkart think that fat cheeks may be particularly important: A baby’s plumpness may be a signal that it’s especially worth investing in.

The way a baby acts is just as important as the way it looks. Even though babies can’t talk, they gesture and make eye contact. Studies show that human infants already understand and react to the emotions and desires of others. Drs. Hrdy and Burkart argue that these very early abilities for social cooperation and emotional intelligence evolved to help attract caregivers.

They also suggest that once these abilities were in place in babies, they allowed more cooperation between adults as well. All those mothers and fathers and alloparents had to coordinate their efforts to take care of the babies. So there was a kind of benign evolutionary circle: As babies became more socially skilled, they were better at attracting caregivers, and when they grew up they became better caregivers themselves.

So the story arc of “The Mandalorian” is also the story of human evolution. He rescues Baby Yoda, but Baby Yoda also rescues him. For adults, taking care of adorable babies together lets us escape from isolation and conflict so we can care for each other, too.

2019

WHY THE OLD LOOK DOWN ON THE YOUNG

Ever since the Greeks, people have been complaining that the next generation is a disappointment. Nowadays, it’s Boomers fighting with those aggravating, avocado-toast crunching, emoji-texting millennials. The feeling is seductive—but isn’t it really an illusion? After all, the old folks who are complaining were once on the receiving end of the same complaints themselves. In the 1960s, the Boomers’ parents denounced them as irresponsible hippies. Have people really been steadily deteriorating since ancient times?

In a new paper in the journal Science Advances, John Protzko and Jonathan Schooler of the University of California at Santa Barbara call this feeling the “kids these days” effect. And their research suggests that it has as much to do with how we think about ourselves as it does with those darned kids.

The researchers studied a sample of 1,824 people, chosen to be representative of the U.S. population. They asked the participants about how the next generation compared with earlier ones—in particular, whether they were respectful, intelligent and well-read. Overall, people gave the young lower ratings, in keeping with the “kids these days” effect.

But the interesting thing was that people responded differently depending on what they were like themselves. People who cared most about respect were most likely to say that the next generation was disrespectful. Those who scored highest on an IQ test were most likely to say that the next generation was less intelligent. And those who did best on an author-recognition test were most likely to say that the next generation didn’t like reading. It seems that older people weren’t responding to objective facts about the young; instead, they were making subjective comparisons in which they themselves came off best.

Most significantly, Dr. Protzko and Dr. Schooler showed that when people’s view of themselves changed, so did their view of the next generation. In one part of the experiment, researchers told participants that they had either scored very well or very badly on the author-recognition test and then asked them to make judgments about the reading abilities of the young. When people believed that they were worse readers themselves, they also were less likely to think badly of the next generation.

Dr. Protzko and Dr. Schooler think the “kids these days” illusion works like this. Older people who excel in a particular trait look at younger people and see that, on average, they are less well-read, respectful or intelligent than they are themselves. Then they compare those young people to their own memories of what they were like at the same age.

But those memories are unreliable. Studies by the Stanford psychologist Lee Ross have shown that we tend to adjust our view of our past selves to match the present. For example, we tend to think that our past political views are much closer to the ones we hold now than they actually were.

In addition to overestimating how much the past resembled the present, people who excel in a particular trait forget that they aren’t typical of their own generation. They may generalize the statement “I loved to read when I was young” to conclude “and everybody else did too.” When we complain about the next generation, we’re actually comparing them to an idealized version of our own past, obscured by the flattering fog of memory.

PARENTS NEED TO HELP THEIR CHILDREN TAKE RISKS

Today’s children and teenagers seem to be taking fewer risks. The trend has had some good effects, like decreases in teenage pregnancy, drug use and even accidents. On the other hand, there has been an equally dramatic increase in anxiety in children and teenagers.

If life is less risky, why are young people more fearful? A new study in the journal Nature Human Behavior, by Nim Tottenham at Columbia University, Regina Sullivan at New York University and their colleagues, suggests an answer. Young people are designed to take risks and avoiding them too much may lead to anxiety. But productive risk-taking depends on having a sense of safety—knowing that a parent is there in the background to take care of you.

The study takes off from one of the oldest results in psychology. Put a rat in a maze where, if it goes down a certain path, it receives an electric shock. The next time it’s put in the maze, the rat will avoid the path that led to the shock. This kind of “avoidance learning” is fundamental, but it has an important drawback: If the rat always avoids the risky path, he will never learn whether the risk is still there or how to cope with it.

Scientists think that avoidance learning may be part of the mechanism behind the development of anxiety, phobias and PTSD. One rocky flight can make you terrified to get on a plane, and so can keep you from learning that most flights are just fine. Counter-intuitively, the best cure for a phobia is to gradually expose the patient to the scary stimulus until their brain is convinced that no harm will actually result. (A psychologist friend of mine cured his snake phobia by raising a snake in his home.)

The classic maze studies were done with adult rats. But in a 2006 study, Prof. Sullivan and her colleagues found that young rats—the equivalent of human children and teenagers—react very differently. Remarkably, they actually preferred the path that led to the shock, choosing a risky but informative experience over a safe and boring one.

But the young rats only took the risk if their mother was present. It’s as if their mother’s presence was a cue that nothing really terrible would happen, allowing the young rats to confidently explore and learn about their environment.

In the new study, Prof. Tottenham and Prof. Sullivan found the same result with a group of 106 preschool children. The children were shown two shapes, one of which was accompanied by a loud, unpleasant noise. Sometimes the child’s parent was present during this part of the experiment, and sometimes they weren’t.

Then the children were invited to crawl through one of two tunnels to get a prize—one marked with the aversive shape and one with the innocuous one. When the parent had been present during their introduction to the shapes, the young children preferred to explore the tunnel marked with the shape that had led to the unpleasant noise. But when the parents had been absent, the children preferred the innocuous shape.

More than 50 years ago, the psychologist John Bowlby suggested that the secure base of “attachment”—the unconditional love that links parents and children—is what allows children to explore the world, and these experiments suggest that he was right. Keeping children from ever taking risks or experiencing their consequences may be counterproductive. But a sense of parental care and stability appears to be just what’s needed for children to take risks productively and learn something new.

TEENAGE REBELS WITH A CAUSE

Teenagers are paradoxical. That’s a mild and detached way of saying something that parents often express with considerably stronger language. But the paradox is scientific as well as personal. In adolescence, helpless and dependent children who have relied on grown-ups for just about everything become independent people who can take care of themselves and help each other. At the same time, once cheerful and compliant children become rebellious teenage risk-takers, often to the point of self-destruction. Accidental deaths go up dramatically in adolescence.

A new study published in the journal Child Development, by Eveline Crone of the University of Leiden and colleagues, suggests that the positive and negative sides of teenagers go hand in hand. The study is part of a new wave of thinking about adolescence. For a long time, scientists and policy makers concentrated on the idea that teenagers were a problem that needed to be solved. The new work emphasizes that adolescence is a time of opportunity as well as risk.

The researchers studied “prosocial” and rebellious traits in more than 200 children and young adults, ranging from 11 to 28 years old. The participants filled out questionnaires about how often they did things that were altruistic and positive, like sacrificing their own interests to help a friend, or rebellious and negative, like getting drunk or staying out late.

Other studies have shown that rebellious behavior increases as you become a teenager and then fades away as you grow older. But the new study shows that, interestingly, the same pattern holds for prosocial behavior. Teenagers were more likely than younger children or adults to report that they did things like unselfishly help a friend.

Most significantly, there was a positive correlation between prosociality and rebelliousness. The teenagers who were more rebellious were also more likely to help others. The good and bad sides of adolescence seem to develop together.

Is there some common factor that underlies these apparently contradictory developments? One idea is that teenage behavior is related to what researchers call “reward sensitivity.” Decision-making always involves balancing rewards and risks, benefits and costs. “Reward sensitivity” measures how much reward it takes to outweigh risk.

Teenagers are particularly sensitive to social rewards—winning the game, impressing a new friend, getting that boy to notice you. Reward sensitivity, like prosocial behavior and risk-taking, seems to go up in adolescence and then down again as we age. Somehow, when you hit 30, the chance that something exciting and new will happen at that party just doesn’t seem to outweigh the effort of getting up off the couch.

The study participants filled out a separate “fun-seeking” questionnaire that measured reward sensitivity with statements like “I’m always willing to try something new if I think it will be fun.” This scale correlated with both prosociality and rebelliousness. What’s more, the researchers were able to track the responses of participants over a four-year period and found that those who had been most eager for experience when they were younger became the most rebellious teenagers—but also the most altruistic.

This new research suggests that Cyndi Lauper was right: Girls (and boys) just wanna have fun, and that’s what makes them into paradoxically good and bad, rebellious and responsible teenagers.

HOW EARLY DO CULTURAL DIFFERENCES START

Do our culture and language shape the way we think? A new paper in the Proceedings of the National Academy of Sciences, by Caren Walker at the University of California at San Diego, Alex Carstensen at Stanford and their colleagues, tried to answer this ancient question. The researchers discovered that very young Chinese and American toddlers start out thinking about the world in similar ways. But by the time they are 3 years old, they are already showing differences based on their cultures.

Dr. Walker’s research took off from earlier work that she and I did together at the University of California at Berkeley. We wanted to know whether children could understand abstract relationships such as “same” and “different.” We showed children of various ages a machine that lights up when you put a block of a certain color and shape on it. Even toddlers can easily figure out that a green block makes the machine go while a blue block doesn’t.

But what if the children saw that two objects that were the same—say, two red square blocks—made the machine light up, while two objects that were different didn’t? We showed children this pattern and asked them to make the machine light up, giving them a choice between a tray with two new identical objects—say, two blue round blocks—or another tray with two different objects.

At 18 months old, toddlers had no trouble figuring out that the relationship between the blocks was the important thing: They put the two similar objects on the machine. But much to our surprise, older children did worse. Three-year-olds had a hard time figuring out that the relationship between the blocks was what mattered. The 3-year-olds had actually learned that the individual objects were more important than the relationships between them.

But these were all American children. Dr. Walker and her colleagues repeated the machine experiment with children in China and found a different result. The Chinese toddlers, like the toddlers in the U.S., were really good at learning the relationships; but so were the 3-year-olds. Unlike the American children, they hadn’t developed a bias toward objects.

In fact, when they saw an ambiguous pattern, which could either be due to something about the individual objects or something about the relationships between them, the Chinese preschoolers actually preferred to focus on the relationships. The American children focused on the objects.

The toddlers in both cultures seemed to be equally open to different ways of thinking. But by age 3, something about their everyday experiences had already pushed them to focus on different aspects of the world. Language could be part of the answer: English emphasizes nouns much more than Chinese does, which might affect the way speakers of each language think about objects.

Of course, individuals and relationships are both important in the social and physical worlds. And cultural conditioning isn’t absolute: American adults can reason about relationships, just as Chinese adults can reason about objects. But the differences in focus and attention, in what seems obvious and what seems unusual, may play out in all sorts of subtle differences in the way we think, reason and act. And those differences may start to emerge when we are very young children.

THE EXPLOSIVE EVOLUTION OF CONSCIOUSNESS

Where does consciousness come from? When and how did it evolve? The one person I’m sure is conscious is myself, of course, and I’m willing to believe that my fellow human beings, and familiar animals like cats and dogs, are conscious too. But what about bumblebees and worms? Or clams, oak trees and rocks?

Some philosophers identify consciousness with the complex, reflective, self-conscious experiences that we have when, say, we are sitting in an armchair and thinking about consciousness. As a result, they argue that even babies and animals aren’t really conscious. At the other end of the spectrum, some philosophers have argued for “pan-psychism,” the idea that consciousness is everywhere, even in atoms.

Recently, however, a number of biologists and philosophers have argued that consciousness was born from a specific event in our evolutionary history: the Cambrian explosion. A new book, “The Evolution of the Sensitive Soul” by the Israeli biologists Simona Ginsburg and Eva Jablonka, makes an extended case for this idea.

For around 100 million years, from about 635 to 542 million years ago, the first large multicellular organisms emerged on Earth. Biologists call this period the Ediacaran Garden—a time when, around the globe, a rich variety of strange creatures spent their lives attached to the ocean floor, where they fed, reproduced and died without doing very much in between. There were a few tiny slugs and worms toward the end of this period, but most of the creatures, such as the flat, frond-like, quilted Dickinsonia, were unlike any plants or animals living today.

Then, quite suddenly by geological standards, most of these creatures disappeared. Between 530 and 520 million years ago, they were replaced by a remarkable proliferation of animals who lived quite differently. These animals started to move, to have brains and eyes, to seek out prey and avoid predators. Some of the creatures in the fossil record seem fantastic—like Anomolocaris, a three-foot-long insectlike predator, and Opabinia, with its five eyes and trunk-like proboscis ending in a grasping claw. But they included the ancestors of all current species of animals, from insects, crustaceans and mollusks to the earliest vertebrates, the creatures who eventually turned into us.

But other children saw the opposite pattern—just one example of the color rule, followed by four examples of the shape rule. Those children rationally switched to the shape rule: If the plaque showed a red square, they would choose a blue square rather than a red circle to make the machine go. In other words, the children acted like good scientists. If there was more evidence for their current belief they held on to it, but if there was more evidence against it then they switched.

Of course, the children in this study had some advantages that adults don’t. They could see the evidence with their own eyes and they trusted the experimenter. Most of our scientific evidence about how the world works—evidence about climate change or vaccinations, for example—comes to us in a much more roundabout way and depends on a long chain of testimony and trust.

Applying our natural scientific reasoning abilities in these contexts is more challenging, but there are hopeful signs. A new paper in PNAS by Gordon Pennycook and David Rand at Yale shows that ordinary people are surprisingly good at rating how trustworthy sources of information are, regardless of ideology. The authors suggest that social media algorithms could incorporate these trust ratings, which would help us to use our inborn rationality to make better decisions in a complicated world.

PSYCHEDELICS AS A PATH TO SOCIAL LEARNING

How do psychedelic drugs work? And can psychedelic experiences teach you something? People often say that these experiences are important, revelatory, life-changing. But how exactly does adding a chemical to your brain affect your mind?

The renaissance of scientific psychedelic research may help to answer these questions. A new study in the journal Nature by Gul Dolen at Johns Hopkins University and her colleagues explored how MDMA works in mice. MDMA, also known as Ecstasy, is the illegal and sometimes very dangerous “love drug” that fueled raves in the 1980s and is still around today. Recent research, though, suggests that MDMA may be effective in treating PTSD and anxiety, and the FDA has approved further studies to explore these possibilities. The new study shows exactly how MDMA influences the brain, at least in mice: It restores early openness to experience, especially social experience, and so makes it easier for the mice to learn from new social information.

In both mice and humans, different parts of the brain are open to different kinds of information at different times. Neuroscientists talk about “plasticity”—the ability of the brain to change as a result of new experiences. Our brains are more plastic in childhood and then become more rigid as we age. In humans, the visual system has a “sensitive period” in the first few years when it can be rewired by experience—that is why it’s so important to correct babies’ vision problems. There is a different sensitive period for language: Language learning gets noticeably harder at puberty.

Similarly, Dr. Dolen found that there was a sensitive period for social learning in mice. The mice spent time with other mice in one colored cage and spent time alone in a different-colored cage. The young mice would learn to move toward the color that was associated with the social experience, and this learning reached a peak in adolescence (“Hey, let’s hit the red club where the cool kids hang out!”). Normally, the adult mice stopped learning this connection (“Who cares? I’d rather just stay home and watch TV”).

The researchers showed that this was because the younger mice had more plasticity in the nucleus accumbens, a part of the brain that is involved in motivation and learning. But after a dose of MDMA, the adult mice were able to learn once more, and they continued to learn the link for several weeks afterward.

Unlike other psychedelics, MDMA makes people feel especially close to the other people around them. (Ravers make “cuddle puddles,” a whole group of people locked in a collective embrace.) The new study suggests that this has something to do with the particular chemical profile of the drug. The social plasticity effect depended on a combination of two different “neurotransmitters”: serotonin, which seems to be involved in plasticity and psychedelic effects in general, and oxytocin, the “tend and befriend” chemical that is particularly involved in social closeness and trust. So MDMA seems to work by making the brain more open in general but especially more open to being with and learning about others.

This study, like an increasing number of others, suggests that psychedelic chemicals can make the brain more open to learning and change. What gets learned or changed, though, depends on the particular chemical, the particular input that reaches the brain, and the particular information that reaches the mind.

A psychedelic experience might be just entertaining, or even terrifying or destructive—certainly not something for casual experimentation. But in the right therapeutic setting, it might actually be revelatory.

WHAT AI IS STILL FAR FROM FIGURING OUT

Everybody’s talking about artificial intelligence. Some people even argue that AI will lead, quite literally, to either immortality or the end of the world. Neither of those possibilities seems terribly likely, at least in the near future. But there is still a remarkable amount of debate about just what AI can do and what it means for all of us human intelligences.

A new book called “Possible Minds: 25 Ways of Looking at AI,” edited by John Brockman, includes a range of big-picture essays about what AI can do and what it might mean for the future. The authors include people who are working in the trenches of computer science, like Anca Dragan, who designs new kinds of AI-directed robots, and Rodney Brooks, who invented the Roomba, a robot vacuum cleaner. But it also includes philosophers like Daniel Dennett, psychologists like Steven Pinker and even art experts like the famous curator Hans Ulrich Obrist.

I wrote a chapter about why AI still can’t solve problems that every 4-year-old can easily master. Although Deep Mind’s Alpha Zero can beat a grand master at computer chess, it would still bomb at Attie Chess—the version of the game played by my 3-year-old grandson Atticus. In Attie Chess, you throw all of the pieces into the wastebasket, pick each one up, try to put them on the board and then throw them all in the wastebasket again. This apparently simple physical task is remarkably challenging even for the most sophisticated robots.

But reading through all the chapters, I began to sense that there’s a more profound way in which human intelligence is different from artificial intelligence, and there’s another reason why Attie Chess may be important.

The trick behind the recent advances in AI is that a human specifies a particular objective for the machine. It might be winning a chess game or distinguishing between pictures of cats and dogs on the internet. But it might also be something more important, like judging whether a work of art deserves to be in a museum or a defendant deserves to be in prison.

The basic technique is to give the computer millions of examples of games, images or previous judgments and to provide feedback. Which moves led to a high score? Which pictures did people label as dogs? What did the curators or judges decide in particular cases? The computer can then use machine learning techniques to try to figure out how to achieve the same objectives. In fact, machines have gotten better and better at learning how to win games or match human judgments. They often detect subtle statistical cues in the data that humans can’t even understand.

But people also can decide to change their objectives. A great judge can argue that slavery should be outlawed or that homosexuality should no longer be illegal. A great curator can make the case for an unprecedented new kind of art, like Cubism or Abstract Expressionism, that is very different from anything in the past. We invent brand new games and play them in new ways. In fact, when children play, they practice setting themselves new objectives, even when, as in Attie Chess, those goals look pretty silly from the adult perspective.

Indeed, the point of each new generation is to create new objectives—new games, new categories and new judgments. And yet, somehow, in a way that we don’t understand at all, we don’t merely slide into relativism. We can decide what is worth doing in a way that AI can’t.

Any new technology, from fire to Facebook, from internal combustion to the internet, brings unforeseen dangers and unintended consequences. Regulating and controlling those technologies is one of the great tasks of each generation, and there are no guarantees of success. In that regard, we have more to fear from natural human stupidity than artificial intelligence. But, so far at least, we are the only creatures who can decide not only what we want but whether we should want it.

YOUNG CHILDREN MAKE GOOD SCIENTISTS

We all know that it’s hard to get people to change their minds, even when they should. Studies show that when people see evidence that goes against their deeply ingrained beliefs, they often just dig in more firmly: Climate change deniers and anti-vaxxers are good examples. But why? Are we just naturally resistant to new facts? Or are our rational abilities distorted by biases and prejudices?

Of course, sometimes it can be perfectly rational to resist changing your beliefs. It all depends on how much evidence you have for those beliefs in the first place, and how strongly you believe them. You shouldn’t overturn the periodic table every time a high-school student blunders in a chemistry lab and produces a weird result. In statistics, new methods increasingly give us a precise way of calculating the balance between old beliefs and new evidence.

Over the past 15 years, my lab and others have shown that, to a surprising extent, even very young children reason in this way. The conventional wisdom is that young children are irrational. They might stubbornly cling to their beliefs, no matter how much evidence they get to the contrary, or they might be irrationally prone to change their minds—flitting from one idea to the next regardless of the facts.

In a new study in the journal Child Development, my student Katie Kimura and I tested whether, on the contrary, children can actually change their beliefs rationally. We showed 4-year-old children a group of machines that lit up when you put blocks on them. Each machine had a plaque on the front with a colored shape on it. First, children saw that the machine would light up if you put a block on it that was the same color as the plaque, no matter what shape it was. A red block would activate a red machine, a blue block would make a blue machine go and so on. Children were actually quite good at learning this color rule: If you showed them a new yellow machine, they would choose a yellow block to make it go.

But then, without telling the children, we changed the rule so that the shape rather than the color made the machine go. Some children saw the machine work on the color rule four times and then saw one example of the shape rule. They held on to their first belief and stubbornly continued to pick the block with the same color as the machine.

But other children saw the opposite pattern—just one example of the color rule, followed by four examples of the shape rule. Those children rationally switched to the shape rule: If the plaque showed a red square, they would choose a blue square rather than a red circle to make the machine go. In other words, the children acted like good scientists. If there was more evidence for their current belief they held on to it, but if there was more evidence against it then they switched.

Of course, the children in this study had some advantages that adults don’t. They could see the evidence with their own eyes and they trusted the experimenter. Most of our scientific evidence about how the world works—evidence about climate change or vaccinations, for example—comes to us in a much more roundabout way and depends on a long chain of testimony and trust.

Applying our natural scientific reasoning abilities in these contexts is more challenging, but there are hopeful signs. A new paper in PNAS by Gordon Pennycook and David Rand at Yale shows that ordinary people are surprisingly good at rating how trustworthy sources of information are, regardless of ideology. The authors suggest that social media algorithms could incorporate these trust ratings, which would help us to use our inborn rationality to make better decisions in a complicated world.

A GENERATIONAL DIVIDE IN THE UNCANNY VALLEY

Over the holidays, my family confronted a profound generational divide. My grandchildren became obsessed with director Robert Zemeckis’s 2009 animated film “A Christmas Carol,” playing it over and over. But the grown-ups objected that the very realistic, almost-but-not-quite-human figures just seemed creepy.

The movie is a classic example of the phenomenon known as “the uncanny valley.” Up to a point, we prefer animated characters who look like people, but when those characters look too much like actual humans, they become weird and unsettling. In a 2012 paper in the journal Cognition, Kurt Gray of the University of North Carolina and Dan Wegner of Harvard demonstrated the uncanny valley systematically. They showed people images of three robots—one that didn’t look human at all, one that looked like a cartoon and one that was more realistic. Most people preferred the cartoony robot and thought the realistic one was strange.

But where does the uncanny valley come from? And why didn’t it bother my grandchildren in “A Christmas Carol”? Some researchers have suggested that the phenomenon is rooted in an innate tendency to avoid humans who are abnormal in some way. But the uncanny valley might also reflect our ideas about minds and brains. A realistic robot looks as if it might have a mind, even though it isn’t a human mind, and that is unsettling. In the Gray study, the more people thought that the robot had thoughts and feelings, the creepier it seemed.

Kimberly Brink and Henry Wellman of the University of Michigan, along with Gray, designed a study to determine whether children experience the uncanny valley. In a 2017 paper in the journal Child Development, they showed 240 children, ages 3 to 18, the same three robots that Gray showed to adults. They asked the children how weird the robots were and whether they could think and feel for themselves. Surprisingly, until the children hit age 9, they didn’t see anything creepy about the realistic robots. Like my grandchildren, they were unperturbed by the almost human.

The development of the uncanny valley in children tracked their developing ideas about robots and minds. Younger children had no trouble with the idea that the realistic robot had a mind. In fact, in other studies, young children are quite sympathetic to robots—they’ll try to comfort one that is fallen or injured. But the older children had a more complicated view. They began to feel that robots weren’t the sort of things that should have minds, and this contributed to their sense that the realistic robot was creepy.

The uncanny valley turns out to be something we develop, not something we’re born with. But this raises a possibility that is itself uncanny. Right now, robots are very far from actually having minds; it is remarkably difficult to get them to do even simple things. But suppose a new generation of children grows up with robots that actually do have minds, or at least act as if they do. This study suggests that those children may never experience an uncanny valley at all. In fact, it is possible that the young children in the study are already being influenced by the increasingly sophisticated machines around them. My grandchildren regularly talk to Alexa and make a point of saying “please” if she doesn’t answer right away.

Long before there were robots, people feared the almost human, from the medieval golem to Frankenstein’s monster. Perhaps today’s children will lead the way in broadening our sympathies to all sentient beings, even artificial ones. I hope so, but I don’t think they’ll ever get me to like the strange creatures in that Christmas movie.

2018

FOR GORILLAS, BEING A GOOD DAD IS SEXY

He was tall and rugged, with piercing blue eyes, blond hair and a magnificent jawline. And what was that slung across his chest? A holster for his Walther PPK? When I saw what the actor Daniel Craig—aka James Bond—was actually toting, my heart skipped a beat. It was an elegant, high-tech baby carrier, so that he could snuggle his baby daughter.

When a paparazzo recently snapped this photo of Mr. Craig, an online kerfuffle broke out after one obtuse commentator accused him of being “emasculated.” Now science has come to Mr. Craig’s defense. A new study of gorillas in Nature Scientific Reports, led by Stacy Rosenbaum and colleagues at Northwestern University and the Dian Fossey Fund, suggests that taking care of babies makes you sexy—at least, if you’re a male gorilla.

The study began with a counterintuitive observation: Even silverback gorillas, those stereotypically fearsome and powerful apes, turn out to love babies. Adult male gorillas consistently groom and even cuddle with little ones. And the gorillas don’t care only about their own offspring; they’re equally willing to hang out with other males’ babies.

The researchers analyzed the records of 23 male gorillas that were part of a group living in the mountains of Rwanda. From 2003 to 2004, observers recorded how much time each male spent in close contact with an infant. By 2014, about 100 babies had been born in the group, and the researchers used DNA, collected from the gorillas’ feces, to work out how many babies each male had fathered. Even when they controlled for other factors like age and status, there turned out to be a strong correlation between caring for children and sexual success. The males who were most attentive to infants sired five times more children than the least attentive. This suggests that females may have been preferentially selecting the males who cared for babies.

These results tell us something interesting about gorillas, but they may also help answer a crucial puzzle about human evolution. Human babies are much more helpless, for a much longer time, than those of other species. That long childhood is connected to our exceptionally large brains and capacity for learning. It also means that we have developed a much wider range of caregivers for those helpless babies. In particular, human fathers help take care of infants and they “pair bond” with mothers.

We take this for granted, but human fathers are actually much more monogamous, and invest more in their babies, than almost any other mammal, including our closest great ape relatives. (Only 5% of mammal species exhibit pair-bonding.) On the other hand, humans aren’t as exclusively monogamous as some other animals—some birds, for example. And human fathers are optional or voluntary caregivers, as circumstances dictate. They don’t always care for their babies, but when they do, they are just as effective and invested as mothers.

Our male primate ancestors must have evolved from the typical indifferent and promiscuous mammalian father into a committed human dad. The gorillas may suggest an evolutionary path that allowed this transformation to take place. And a crucial part of that path may be that men have a fondness for babies in general, whether or not they are biologically related.

Mr. Craig was on to something: You don’t really need dry martinis and Aston Martins to appeal to women. A nice Baby Bjorn will do.

THE COGNITIVE ADVANTAGES OF GROWING OLDER

If, like me, you’re on the wrong side of sixty, you’ve probably noticed those increasingly frequent and sinister “senior moments.” What was I looking for when I came into the kitchen? Did I already take out the trash? What’s old what’s-his-name’s name again?

One possible reaction to aging is resignation: You’re just past your expiration date. You may have heard that centuries ago the average life expectancy was only around 40 years. So you might think that modern medicine and nutrition are keeping us going past our evolutionary limit. No wonder the machine starts to break down.

In fact, recent research suggests a very different picture. The shorter average life expectancy of the past mainly reflects the fact that many more children died young. If you made it past childhood, however, you might well live into your 60s or beyond. In today’s hunter-gatherer cultures, whose way of life is closer to that of our prehistoric ancestors, it’s fairly common for people to live into their 70s. That is in striking contrast to our closest primate relatives, chimpanzees, who very rarely live past their 50s.

There seem to be uniquely human genetic adaptations that keep us going into old age and help to guard against cognitive decline. This suggests that the later decades of our lives are there for a reason. Human beings are uniquely cultural animals; we crucially depend on the discoveries of earlier generations. And older people are well suited to passing on their accumulated knowledge and wisdom to the next generation.

Michael Gurven, an anthropologist at the University of California, Santa Barbara, and his colleagues have been studying aging among the Tsimane, a group in the Bolivian Amazon. The Tsimane live in a way that is more like the way we all lived in the past, through hunting, gathering and small-scale farming of local foods, with relatively little schooling or contact with markets and cities. Many Tsimane are in their 60s or 70s, and some even make it to their 80s.

In a 2017 paper in the journal Developmental Psychology, Prof. Gurven and colleagues gave over 900 Tsimane people a battery of cognitive tasks. Older members of the group had a lot of trouble doing things like remembering a list of new words. But the researchers also asked their subjects to quickly name as many different kinds of fish or plants as they could. This ability improved as the Tsimane got older, peaking around age 40 and staying high even in old age.

Research on Western urban societies has produced similar findings. This suggests that our cognitive strengths and weaknesses change as we age, rather than just undergoing a general decline. Things like short-term memory and processing speed—what’s called “fluid intelligence”—peak in our 20s and decline precipitously in older age. But “crystallized intelligence”—how much we actually know, and how well we can access that knowledge—improves up to middle age, and then declines much more slowly, if at all.

So when I forget what happened yesterday but can tell my grandchildren and students vivid stories about what happened 40 years ago, I may not be falling apart after all. Instead, I may be doing just what evolution intended.

IMAGINARY WORLDS OF CHILDHOOD

In 19th-century England, the Brontë children created Gondal, an imaginary kingdom full of melodrama and intrigue. Emily and Charlotte Brontë grew up to write the great novels “Wuthering Heights” and “Jane Eyre.” The fictional land of Narnia, chronicled by C.S. Lewis in a series of classic 20th-century novels, grew out of Boxen, an imaginary kingdom that Lewis shared with his brother when they were children. And when the novelist Anne Perry was growing up in New Zealand in the 1950s, she and another girl created an imaginary kingdom called Borovnia as part of an obsessive friendship that ended in murder—the film “Heavenly Creatures” tells the story.

But what about Abixia? Abixia is an island nation on the planet Rooark, with its own currency (the iinter, divided into 12 skilches), flag and national anthem. It’s inhabited by cat-humans who wear flannel shirts and revere Swiss army knives—the detailed description could go on for pages. And it was created by a pair of perfectly ordinary Oregon 10-year-olds.

Abixia is a “paracosm,” an extremely detailed and extensive imaginary world with its own geography and history. The psychologist Marjorie Taylor at the University of Oregon and her colleagues discovered Abixia, and many other worlds like it, by talking to children. Most of what we know about paracosms comes from writers who described the worlds they created when they were children. But in a paper forthcoming in the journal Child Development, Prof. Taylor shows that paracosms aren’t just the province of budding novelists. Instead, they are a surprisingly common part of childhood.

Prof. Taylor asked 169 children, ages eight to 12, whether they had an imaginary world and what it was like. They found that about 17 percent of the children had created their own complicated universe. Often a group of children would jointly create a world and maintain it, sometimes for years, like the Brontë sisters or the Lewis brothers. And grown-ups were not invited in.

Prof. Taylor also tried to find out what made the paracosm creators special. They didn’t score any higher than other children in terms of IQ, vocabulary, creativity or memory. Interestingly, they scored worse on a test that measured their ability to inhibit irrelevant thoughts. Focusing on the stern and earnest real world may keep us from wandering off into possible ones.

But the paracosm creators were better at telling stories, and they were more likely to report that they also had an imaginary companion. In earlier research, Prof. Taylor found that around 66% of preschoolers have imaginary companions; many paracosms began with older children finding a home for their preschool imaginary friends.

Children with paracosms, like children with imaginary companions, weren’t neurotic loners either, as popular stereotypes might suggest. In fact, if anything, they were more socially skillful than other children.

Why do imaginary worlds start to show up when children are eight to 12 years old? Even when 10-year-olds don’t create paracosms, they seem to have a special affinity for them—think of all the young “Harry Potter” fanatics. And as Prof. Taylor points out, paracosms seem to be linked to all the private clubhouses, hidden rituals and secret societies of middle childhood.

Prof. Taylor showed that preschoolers who create imaginary friends are particularly good at understanding other people’s minds—they are expert at everyday psychology. For older children, the agenda seems to shift to what we might call everyday sociology or geography. Children may create alternative societies and countries in their play as a way of learning how to navigate real ones in adult life.

Of course, most of us leave those imaginary worlds behind when we grow up—the magic portals close. The mystery that remains is how great writers keep the doors open for us all.

LIKE US, WHALES MAY BE SMART BECAUSE THEY'RE SOCIAL

In recent weeks, an orca in the Pacific Northwest carried her dead calf around with her for 17 days. It looked remarkably like grief. Indeed, there is evidence that many cetaceans—that is, whales, dolphins and porpoises—have strong and complicated family and social ties. Some species hunt cooperatively; others practice cooperative child care, taking care of one another’s babies.

The orcas, in particular, develop cultural traditions. Some groups hunt only seals, others eat only salmon. What’s more, they are one of very few species with menopausal grandmothers. Elderly orca females live well past their fertility and pass on valuable information and traditions to their children and grandchildren. Other cetaceans have cultural traditions too: Humpback whales learn their complex songs from other whales as they pass through the breeding grounds in the southern Pacific Ocean.

We also know that cetaceans have large and complex brains, even relative to their large bodies. Is there a connection? Is high intelligence the result of social and cultural complexity? This question is the focus of an important recent study by researchers Kieran Fox, Michael Muthukrishna and Suzanne Shultz, published last October in the journal Nature Ecology and Evolution.

Their findings may shed light on human beings as well. How and why did we get to be so smart? After all, in a relatively short time, humans developed much larger brains than their primate relatives, as well as powerful social and cultural skills. We cooperate with each other—at least most of the time—and our grandmothers, like grandmother orcas, pass on knowledge from one generation to the next. Did we become so smart because we are so social?

Humans evolved millions of years ago, so without a time machine, it’s hard to find out what actually happened. A clever alternate approach is to look at the cetaceans. These animals are very different from us, and their evolutionary history diverged from ours 95 million years ago. But if there is an intrinsic relationship between intelligence and social life, it should show up in whales and dolphins as well as in humans.

Dr. Fox and colleagues compiled an extensive database, recording as much information as they could find about 90 different species of cetaceans. They then looked at whether there was a relationship between the social lives of these animals and their brain size. They discovered that species living in midsized social groups, with between two and 50 members, had the largest brains, followed by animals who lived in very large pods with hundreds of animals. Solitary animals had the smallest brains. The study also found a strong correlation between brain size and social repertoire: Species who cooperated, cared for each other’s young and passed on cultural traditions had larger brains than those who did not.

Which came first, social complexity or larger brains? Dr. Fox and colleagues conducted sophisticated statistical analyses that suggested there was a feedback loop between intelligence and social behavior. Living in a group allowed for more complex social lives that rewarded bigger brains. Animals who excelled at social interaction could obtain more resources, which allowed them to develop yet bigger brains. This kind of feedback loop might also account for the explosively fast evolution of human beings.

Of course, intelligence is a relative term. The orcas’ cognitive sophistication and social abilities haven’t preserved them from the ravages of environmental change. The orca grieving her dead baby was, sadly, all too typical of her endangered population. It remains to be seen whether our human brains can do any better.

FOR BABIES, LIFE MAY BE A TRIP

What is it like to be a baby? Very young children can’t tell us what their experiences are like, and none of us can remember the beginnings of our lives. So it would seem that we have no way of understanding baby consciousness, or even of knowing if babies are conscious at all.

But some fascinating new neuroscience research is changing that. It turns out that when adults dream or have psychedelic experiences, their brains are functioning more like children’s brains. It appears that the experience of babies and young children is more like dreaming or tripping than like our usual grown-up consciousness.

As we get older, the brain’s synapses—the connections between neurons—start to change. The young brain is very “plastic,” as neuroscientists say: Between birth and about age 5, the brain easily makes new connections. A preschooler’s brain has many more synapses than an adult brain. Then comes a kind of tipping point. Some connections, especially the ones that are used a lot, become longer, stronger and more efficient. But many other connections disappear—they are “pruned.”

What’s more, different areas of the brain are active in children and adults. Parts of the back of the brain are responsible for things like visual processing and perception. These areas mature quite early and are active even in infancy. By contrast, areas at the very front of the brain, in the prefrontal cortex, aren’t completely mature until after adolescence. The prefrontal cortex is the executive office of the brain, responsible for focus, control and long-term planning.

Like most adults, I spend most of my waking hours thinking about getting things done. Scientists have discovered that when we experience the world in this way, the brain sends out signals along the established, stable, efficient networks that we develop as adults. The prefrontal areas are especially active and have a strong influence on the rest of the brain. In short, when we are thinking like grown-ups, our brains look very grown-up too.

But recently, neuroscientists have started to explore other states of consciousness. In research published in Nature in 2017, Giulio Tononi of the University of Wisconsin and colleagues looked at what happens when we dream. They measured brain activity as people slept, waking them up at regular intervals to ask whether they had been dreaming. Then the scientists looked at what the brain had been doing just before the sleepers woke up. When people reported dreaming, parts of the back of the brain were much more active—like the areas that are active in babies. The prefrontal area, on the other hand, shuts down during sleep.

A number of recent studies also explore the brain activity that accompanies psychedelic experiences. A study published last month in the journal Cell by David Olson of the University of California, Davis, and colleagues looked at how mind-altering chemicals affect synapses in rats. They found that a wide range of psychedelic chemicals made the brain more plastic, leading brain cells to grow more connections. It’s as if the cells went back to their malleable, infantile state.

In other words, the brains of dreamers and trippers looked more like those of young children than those of focused, hard-working adults. In a way, this makes sense. When you have a dream or a psychedelic experience, it’s hard to focus your attention or control your thoughts—which is why reporting these experiences is notoriously difficult. At the same time, when you have a vivid nightmare or a mind-expanding experience, you certainly feel more conscious than you are in boring, everyday life.

In the same way, an infant’s consciousness may be less focused and controlled than an adult’s but more vivid and immediate, combining perception, memory and imagination. Being a baby may be both stranger and more intense than we think.

WHO'S MOST AFRAID TO DIE? A SURPRISE

Why am I afraid to die? Maybe it’s the “I” in that sentence. It seems that I have a single constant self—the same “I” who peered out from my crib is now startled to see my aging face in the mirror 60 years later. It’s my inner observer, chief executive officer and autobiographer. It’s terrifying to think that this “I” will just disappear.

But what if this “I” doesn’t actually exist? For more than 2,000 years, Buddhist philosophers have argued that the self is an illusion, and many contemporary philosophers and psychologists agree. Buddhists say this realization should make us fear death less. The person I am now will be replaced by the person I am in five years, anyway, so why worry if she vanishes for good?

A recent paper in the journal Cognitive Science has an unusual combination of authors. A philosopher, a scholar of Buddhism, a social psychologist and a practicing Tibetan Buddhist tried to find out whether believing in Buddhism really does change how you feel about your self—and about death.

The philosopher Shaun Nichols of the University of Arizona and his fellow authors studied Christian and nonreligious Americans, Hindus and both everyday Tibetan Buddhists and Tibetan Buddhist monks. Among other questions, the researchers asked participants about their sense of self—for example, how strongly they believed they would be the same five years from now. Religious and nonreligious Americans had the strongest sense of self, and the Buddhists, especially the monks, had the least.

In previous work, Prof. Nichols and other colleagues showed that changing your sense of self really could make you act differently. A weaker sense of self made you more likely to be generous to others. The researchers in the new study predicted that the Buddhists would be less frightened of death.

The results were very surprising. Most participants reported about the same degree of fear, whether or not they believed in an afterlife. But the monks said that they were much moreafraid of death than any other group did.

Why would this be? The Buddhist scholars themselves say that merely knowing there is no self isn’t enough to get rid of the feeling that the self is there. Neuroscience supports this idea. Our sense of self, and the capacities like autobiographical memory and long-term planning that go with it, activates something called the default mode network—a set of connected brain areas. Long-term meditators have a less-active default mode network, but it takes them years to break down the idea of the self, and the monks in this study weren’t expert meditators.

Another factor in explaining why these monks were more afraid of death might be that they were trained to think constantly about mortality. The Buddha, perhaps apocryphally, once said that his followers should think about death with every breath. Maybe just ignoring death is a better strategy.

There may be one more explanation for the results. Our children and loved ones are an extension of who we are. Their survival after we die is a profound consolation, even for atheists. Monks give up those intimate attachments.

I once advised a young man at Google headquarters who worried about mortality. He agreed that a wife and children might help, but even finding a girlfriend was a lot of work. He wanted a more efficient tech solution—like not dying. But maybe the best way of conquering both death and the self is to love somebody else.

CURIOSITY IS A NEW POWER IN ARTIFICIAL INTELLIGENCE

Suddenly, computers can do things that seemed impossible not so many years ago, from mastering the game of Go and acing Atari games to translating text and recognizing images. The secret is that these programs learn from experience. The great artificial-intelligence boom depends on learning, and children are the best learners in the universe. So computer scientists are starting to look to children for inspiration.

Everybody knows that young children are insatiably curious, but I and other researchers in the field of cognitive development, such as Laura Schulz at the Massachusetts Institute of Technology, are beginning to show just how that curiosity works. Taking off from these studies, the computer scientists Deepak Pathak and Pulkit Agrawal have worked with others at my school, the University of California, Berkeley, to demonstrate that curiosity can help computers to learn, too.

One of the most common ways that machines learn is through reinforcement. The computer keeps track of when a particular action leads to a reward—like a higher score in a videogame or a winning position in Go. The machine tries to repeat rewarding sequences of actions and to avoid less-rewarding ones.

This technique still has trouble, however, with even simple videogames such as Super Mario Bros.—a game that children can master easily. One problem is that before you can score, you need to figure out the basics of how Super Mario works—the players jump over columns and hop over walls. Simply trying to maximize your score won’t help you learn these general principles. Instead, you have to go out and explore the Super Mario universe.

Another problem with reinforcement learning is that programs can get stuck trying the same successful strategy over and over, instead of risking something new. Most of the time, a new strategy won’t work better, but occasionally it will turn out to be much more effective than the tried-and-true one. You also need to explore to find that out.

The same holds for real life, of course. When I get a new smartphone, I use something like reinforcement learning: I try to get it to do specific things that I’ve done many times before, like call someone up. (How old school is that!) If the call gets made, I stop there. When I give the phone to my 4-year-old granddaughter, she wildly swipes and pokes until she has discovered functions that I didn’t even suspect were there. But how can you build that kind of curiosity into a computer?

Drs. Pathak and Agrawal have designed a program to use curiosity in mastering videogames. It has two crucial features to do just that. First, instead of just getting rewards for a higher score, it’s also rewarded for being wrong. The program tries to predict what the screen will look like shortly after it makes a new move. If the prediction is right, the program won’t make that move again—it’s the same old same old. But if the prediction is wrong, the program will make the move again, trying to get more information. The machine is always driven to try new things and explore possibilities.

Another feature of the new program is focus. It doesn’t pay attention to every unexpected pixel anywhere on the screen. Instead, it concentrates on the parts of the screen that can influence its actions, like the columns or walls in Mario’s path. Again, this is a lot like a child trying out every new action she can think of with a toy and taking note of what happens, even as she ignores mysterious things happening in the grown-up world. The new program does much better than the standard reinforcement-learning algorithms.

Super Mario is still a very limited world compared with the rich, unexpected, unpredictable real world that every 4-year-old has to master. But if artificial intelligence is really going to compete with natural intelligence, more childlike insatiable curiosity may help.

GRANDPARENTS: THE STORYTELLERS WHO BIND US

‘Grandmom, I love Mommy most, of course, but you do tell the best stories—especially Odysseus and the Cyclops.” This authentic, if somewhat mixed, review from my grandson may capture a profound fact about human nature. A new study by Michael Gurven and colleagues suggests that grandparents really may be designed to pass on the great stories to their grandchildren.

One of the great puzzles of human evolution is why we have such a distinctive “life history.” We have much longer childhoods than any other primate, and we also live much longer, well past the age when we can fully pull our weight. While people in earlier generations had a shorter life expectancy overall, partly because many died in childhood, some humans have always lived into their 60s and 70s. Researchers find it especially puzzling that female humans have always lived well past menopause. Our closest primate relatives die in their 50s.

Perhaps, some anthropologists speculate, grandparents evolved to provide another source of food and care for all those helpless children. I’ve written in these pages about what the anthropologist Kristen Hawkes of the University of Utah has called “the grandmother hypothesis.” Prof. Hawkes found that in forager cultures, also known as hunter-gatherer societies, the food that grandmothers produce makes all the difference to their grandchildren’s survival.

In contrast, Dr. Gurven and his colleagues focus more on how human beings pass on information from one generation to another. Before there was writing, human storytelling was one of the most important kinds of cultural transmission. Could grandparents have adapted to help that process along?

Dr. Gurven’s team, writing earlier this year in the journal Evolution and Human Behavior, studied the Tsimane in Amazonia, a community in the Amazon River basin who live as our ancestors once did. The Tsimane, more than 10,000 strong, gather and garden, hunt and fish, without much involvement in the market economy. And they have a rich tradition of stories and songs. They have myths about Dojity and Micha, creators of the Earth, with the timeless themes of murder, adultery and revenge. They also sing melancholy songs about rejected love (the blues may be a universal part of human nature).

During studies of the Tsimane spread over a number of years, Dr. Gurven and his colleagues conducted interviews to find out who told the most stories and sang the most songs, who was considered the best in each category and who the audience was for these performances. The grandparents, people from age 60 to 80, most frequently came out on top. While only 5% of Tsimane aged 15 to 29 told stories, 44% of those aged 60 to 80 did. And the elders’ most devoted audiences were their much younger kin. When the researchers asked where the Tsimane had heard stories, 84% of them came from older relatives other than parents, particularly grandparents.

This preference for grandparents may be tied to the anthropological concept of “alternate generations.” Parents may be more likely to pass on the practical skills of using a machete or avoiding a jaguar, while their own parents pass on the big picture of how a community understands the world and itself. Other studies have found that relations between grandparents and grandchildren tend to be more egalitarian than the “I told you not to do that” relationship between so many parents and children.

Grandparents may play a less significant cultural role in a complex, mobile modern society. Modern pop stars and TV showrunners are more likely to be millennial than menopausal. But when they get the chance, grandmas and grandpas still do what they’ve done across the ages—turning the attention of children to the very important business of telling stories and singing songs.

ARE BABIES ABLE TO SEE WHAT OTHERS FEEL?

When adults look out at other people, we have what psychologists and philosophers call a “theory of mind”—that is, we think that the people around us have feelings, emotions and beliefs just as we do. And we somehow manage to read complex mental states in their sounds and movements.

But what do babies see when they look out at other people? They know so much less than we do. It’s not hard to imagine that, as we coo and mug for them, they only see strange bags of skin stuffed into clothes, with two restless dots at the top and a hole underneath that opens and closes.

Our sophisticated grown-up understanding of other people develops through a long process of learning and experience. But babies may have more of a head start than we imagine. A new study by Andrew Meltzoff and his colleagues at the University of Washington, published in January in the journal Developmental Science, finds that our connection to others starts very early.

Dr. Meltzoff has spent many years studying the way that babies imitate the expressions and actions of other people. Imitation suggests that babies do indeed connect their own internal feelings to the behavior of others. In the new study, the experimenters looked at how this ability is reflected in baby’s brains.

Studies with adults have shown that some brain areas activate in the same way when I do something as when I see someone else do the same thing. But, of course, adults have spent many years watching other people and experiencing their own feelings. What about babies?

The trouble is that studying babies’ brains is really hard. The typical adult studies use an FMRI (functional magnetic resonance imaging) machine: Participants have to lie perfectly still in a very noisy metal tube. Some studies have used electroencepholography to measure baby’s brain waves, but EEG only tells you when a baby’s brain is active. It doesn’t say where that brain activity is taking place.

Dr. Meltzoff and colleagues have been pioneers in using a new technique called magnetoencephalography with very young babies. Babies sit in a contraption that’s like a cross between a car seat and an old-fashioned helmet hairdryer. The MEG machine measures very faint and subtle magnetic signals that come from the brain, using algorithms to correct for a wriggling baby’s movements.

In this study, the experimenters used MEG with 71 very young babies—only seven months old. They recorded signals from a part of the brain called the “somatosensory” cortex. In adults, this brain area is a kind of map of your body. Sensations in different body parts activate different “somatosensory” areas, which correspond to the arrangement of the body: Hand areas are near arm areas, leg areas are near feet.

One group of babies felt a small puff of air on their hand or their foot. The brain activation pattern for hands and feet turned out to be different, just as it is for grown-ups. Then the experimenters showed other babies a video of an adult hand or foot that was touched by a rod. Surprisingly, seeing a touch on someone else’s hand activated the same brain area as feeling a touch on their own hand, though more faintly. The same was true for feet.

These tiny babies already seemed to connect their own bodily feelings to the feelings of others. These may be the first steps toward a fully-fledged theory of mind. Even babies, it turns out, don’t just see bags of skin. We seem to be born with the ability to link our own minds and the minds of others.

WHAT TEENAGERS GAIN FROM FINE-TUNED SOCIAL RADAR

Figuring out why teenagers act the way they do is a challenge for everybody, scientists as well as parents. For a long time, society and science focused on adolescents’ problems, not on their strengths. There are good reasons for this: Teens are at high risk for accidents, suicide, drug use and overall trouble. The general perception was that the teenage brain is defective in some way, limited by a relatively undeveloped prefrontal cortex or overwhelmed by hormones.

In the past few years, however, some scientists have begun to think differently. They see adolescence as a time of both risk and unusual capacities. It turns out that teens are better than both younger children and adults at solving some kinds of problems.

Teenagers seem to be especially adept at processing social information, particularly social information about their peers. From an evolutionary perspective, this makes a lot of sense. Adolescence is, after all, when you leave the shelter of your parents for the big world outside. A 2017 study by Maya Rosen and Katie McLaughlin of the University of Washington and their colleagues, published in the journal Developmental Science, is an important contribution to this new way of thinking about teens.

Young children don’t have to be terribly sensitive to the way that their parents feel, or even to how other children feel, in order to survive. But for teenagers, figuring out other people’s emotions becomes a crucial and challenging task. Did he just smile because he likes me or because he’s making fun of me? Did she just look away because she’s shy or because she’s angry?

The researchers studied 54 children and teenagers, ranging from 8 to 19 years old. They showed participants a series of faces expressing different emotions. After one face appeared, a new face would show up with either the same expression or a different one. The participants had to say, over the course of 100 trials, whether the new face’s expression matched the old one or was different.

While this was going on, the researchers also used an FMRI scanner to measure the participants’ brain activation. They focused on “the salience network”—brain areas that light up when something is important or relevant, particularly in the social realm.

Early adolescents, aged 14 or so, showed more brain activation when they saw an emotion mismatch than did either younger children or young adults.

Is this sensitivity a good thing or bad? The researchers also gave the participants a questionnaire to measure social anxiety and social problems. They asked the children and adolescents how well different sentences described them. They would say, for example, whether “I’m lonely” or “I don’t like to be with people I don’t know well” was a good description of how they felt. In other studies, these self-rating tests have turned out to be a robust measure of social anxiety and adjustment in the real world.

The researchers found that the participants whose brains reacted more strongly to the emotional expressions also reported fewer social problems and anxiety—they were less likely to say that they were lonely or avoided strangers. Having a brain that pays special attention to other people’s emotions allows you to understand and deal with those emotions better, and so to improve your social life.

The brains of young teenagers were especially likely to react to emotion in this way. And, of course, this period of transition to adult life is especially challenging socially. The young adolescents’ increased sensitivity appears to be an advantage in figuring out their place in the world. Rather than being defective, their brains functioned in a way that helped them deal with the special challenges of teenage life.

2017

THE SMART BUTTERFLY'S GUIDE TO REPRODUCTION

We humans have an exceptionally long childhood, generally bear just one child at a time and work hard to take care of our children. Is this related to our equally distinctive large brains and high intelligence? Biologists say that, by and large, the smarter species of primates and even birds mature later, have fewer babies, and invest more in those babies than do the dimmer species.

“Intelligence” is defined, of course, from a human perspective. Plenty of animals thrive and adapt without a large brain or developed learning abilities.

But how far in the animal kingdom does this relationship between learning and life history extend? Butterflies are about as different from humans as could be—laying hundreds of eggs, living for just a few weeks and possessing brains no bigger than the tip of a pen. Even by insect standards, they’re not very bright. A bug-loving biology teacher I know perpetually complains that foolish humans prefer pretty but vapid butterflies to her brilliant pet cockroaches.

But entomologist Emilie Snell-Rood at the University of Minnesota and colleagues have found a similar relationship of learning to life-history in butterflies. The insects that are smarter have a longer period of immaturity and fewer babies. The research suggests that these humble creatures, which have existed for roughly 50 million years, can teach us something about how to adapt to a quickly changing world.

Climate change or habitat loss drives some animals to extinction. But others alter the development of their bodies or behavior to suit a changing new environment, demonstrating what scientists call “developmental plasticity.” Dr. Snell-Rood wants to understand these fast adaptations, especially those caused by human influence. She has shown, for example, how road-salting has altered the development of curbside butterflies.

Learning is a particularly powerful kind of plasticity. Cabbage white butterflies, the nemesis of the veggie gardener, flit from kale to cabbage to chard, in search of the best host for their eggs after they hatch and larvae start munching. In a 2009 paper in the American Naturalist, Dr. Snell-Rood found that all the bugs start out with a strong innate bias toward green plants such as kale. But some adventurous and intelligent butterflies may accidentally land on a nutritious red cabbage and learn that the red leaves are good hosts, too. The next day those smart insects will be more likely to seek out red, not just green, plants.

In a 2011 paper in the journal Behavioral Ecology, Dr. Snell-Rood showed that the butterflies who were better learners also took longer to reach reproductive maturity, and they produced fewer eggs overall. When she gave the insects a hormone that sped up their development, so that they grew up more quickly, they were worse at learning.

In a paper in the journal Animal Behaviour published this year, Dr. Snell-Rood looked at another kind of butterfly intelligence. The experimenters presented cabbage whites with a choice between leaves that had been grown with more or less fertilizer, and leaves that either did or did not have a dead, carefully posed cabbage white pinned to them.

Some of the insects laid eggs all over the place. But some preferred the leaves that were especially nutritious. What’s more, these same butterflies avoided leaves that were occupied by other butterflies, where the eggs would face more competition. The choosier butterflies, like the good learners, produced fewer eggs overall. There was a trade-off between simply producing more young and taking the time and care to make sure those young survived.

In genetic selection, an organism produces many kinds of offspring, and only the well-adapted survive. But once you have a brain that can learn, even a butterfly brain, you can adapt to a changing environment in a single generation. That will ensure more reproductive success in the long run.

THE POWER OF PRETENDING: WHAT WOULD A HERO DO?

Sometime or other, almost all of us secretly worry that we’re just impostors—bumbling children masquerading as competent adults. Some of us may deal with challenges by pretending to be a fictional hero instead of our unimpressive selves. I vividly remember how channeling Jane Austen’s Elizabeth Bennet got me through the awkwardness of teen courtship. But can you really fake it till you make it?

Two recent studies—by Rachel White of the University of Pennsylvania, Stephanie Carlson of the University of Minnesota and colleagues—describe what they call “The Batman Effect.” Children who pretend that they are Batman (or Dora the Explorer or other heroic figures) do better on measures of self-control and persistence.

In the first study, published in 2015 in the journal Developmental Science, the experimenters gave 48 5-year-olds increasingly challenging problems that required them to use their skills of control and self-inhibition. For example, researchers might ask a child to sort cards according to their color and then suddenly switch to sorting them by shape. Between the ages of 3 and 7, children gradually get better at these tasks.

The experimenter told some of the children to pretend to be powerful fictional characters as they completed these tasks. The children even put on costume props (like Batman’s cape or Dora’s backpack) to help the pretending along. The experimenter said, “Now, you’re Batman! In this game, I want you to ask yourself, ‘Where does Batman think the card should go?’ ” The pretenders did substantially better than the children who tried to solve the task as themselves.

In the second study, published last December in the journal Child Development, the experimenters set up a task so fiendish it might have come from the mind of the Joker. They gave 4- and 6-year-old children a boring and somewhat irritating task on the computer—pressing a button when cheese appeared on the screen and notpressing it when a cat appeared. The children also received a tablet device with an interesting game on it.

The children were told that it was important for them to finish the task on the computer but that, since it was so boring, they could take a break when they wanted to play the game on the tablet instead.

The children then received different kinds of instructions. One group was told to reflect and ask themselves, “Am I working hard?” Other children got to dress up like a favorite heroic character—Batman, Dora and others. They were then told to ask themselves, “Is Batman [or whoever they were playing] working hard?” Once again, pretending helped even the younger children to succeed. They spent more time on the task and less on the distracting tablet.

Last month at a conference of the Cognitive Development Society in Portland, Ore., Dr. Carlson discussed another twist on this experiment. Was it just the distraction of pretending that helped the children or something about playing powerful heroes? She and her colleagues tried to find out by having children pretend to be “Batman on a terrible day.” They donned tattered capes and saw pictures of a discouraged superhero—and they did worse on the task than other children.

These studies provide a more complex picture of how self-control and will power work. We tend to think of these capacities as if they were intrinsic, as if some people just have more control than others. But our attitude, what psychologists call our “mind-set,” may be as important as our abilities.

There is a longstanding mystery about why young children pretend so much and what benefits such play provides. The function of adult pretending—in fiction or drama—Is equally mysterious. In the musical “The King and I,” Oscar Hammerstein II wrote that by whistling a happy tune, “when I fool the people I fear, I fool myself as well.” Pretending, for children and adults, may give us a chance to become the people we want to be.

DO MEN AND WOMEN HAVE DIFFERENT BRAINS?

A few weeks ago, James Damore lost his job at Google after circulating a memo asserting, among other things, that there are major personality and behavioral differences, on average, between the sexes, based on biology. People often think that we can distinguish between biological and cultural causes of behavior and then debate which is more important. An emerging scientific consensus suggests that both sides of this debate are misguided.

Everything about our minds is both biological and cultural, the result of complex, varied, multidirectional, cascading interactions among genes and environments that we are only just beginning to understand. For scientists, the key question is exactly how differences in behavior, to the extent that they exist, emerge and what they imply about future behavior.

Daphna Joel of Tel Aviv University, a leading researcher studying sex differences in the brain, summarizes new research on these questions in recent articles (with colleagues) published in Trends in Cognitive Sciences and Philosophical Transactions of the Royal Society B. The picture she draws is very different from our everyday notions of how sex differences work.

When we think about brain and behavioral differences, we tend to use the model of physical sex differences, such as breasts and beards. These physical differences result from complex interactions among genes, hormones and environments, but in general, the specific features are correlated: There is a male body type and a female one. Breasts and uteruses go together, and they rarely go with beards. Once we’re past puberty, changes in the environment, by and large, will have little effect on the distribution of those features.

Scientists have found that, on average, men and women do differ with respect to some brain and behavioral features, so it’s tempting to think that those differences are like the physical differences—that there is a typical “male” or “female” brain, and then some brains in the middle. As it turns out, however, brains don’t follow this model.

Dr. Joel reports on research that she and her colleagues did on more than a thousand brains, looking at data on both structure and function. On average, Brain Area 1 may be larger in men, while Brain Area 2 is larger in women. But any individual man or woman may have a large Area 1 and a small Area 2 or vice versa. There is little correlation among the features. Brain differences have what they call a “mosaic” pattern, and each of us is a mashup of different “male” and “female” features. In fact, Dr. Joel found that almost half the brains in the sample had a very “male” version of one feature together with a very “female” version of another.

Dr. Joel and colleagues also looked at 25 behaviors that differ on average between men and women—such as playing videogames, scrapbooking, being interested in cosmetics and closely following sports—across 5,000 people. The scientists found a similar mosaic pattern of behaviors: Again, the participants didn’t fall into two clear types.

In addition, they reviewed various studies showing that average sex differences can quickly be altered or even reversed by changes in the environment. In rats, for example, females typically have less-dense receptors in the dorsal hippocampus, which is involved in memory, than do males. But after both sexes experienced a few weeks of mild stress, the pattern reversed: Now the males had less-dense receptors than the females. The reasons for this aren’t entirely clear yet. But if we see a particular sex pattern in one environment—a standard 21st-century university classroom or company, for instance—we have no reason to believe that we will see the same sex pattern in a different environment.

And, of course, one of the distinctive features of humans is that we create new environments all the time. It’s impossible to know beforehand just how an unprecedented new environment will reshape our traits or just which combinations of traits will turn out to be useful. In evolution, as in policy, diversity is a good way to deal with change.

HOW TO GET OLD BRAINS TO THINK LIKE YOUNG ONES

As the saying goes, old dogs—or mice or monkeys or people—can’t learn new tricks. But why? Neuroscientists have started to unravel the brain changes that are responsible. And as a new paper in the journal Science shows, they can even use these research findings to reverse the process. Old mice, at least, really can go back to learning like young ones.

The new study builds on classic work done by Michael Merzenich at the University of California, San Francisco, and colleagues. In the early 2000s they recorded the electrical activity in brain cells and discovered that young animals’ brains would change systematically when they repeatedly heard something new. For instance, if a baby monkey heard a new sound pattern many times, her neurons (brain cells) would adjust to respond more to that sound pattern. Older monkeys’ neurons didn’t change in the same way.

At least part of the reason for this lies in neurotransmitters, chemicals that help to connect one neuron to another. Young animals have high levels of “cholinergic” neurotransmitters that make the brain more plastic, easier to change. Older animals start to produce inhibitory chemicals that counteract the effect of the cholinergic ones. They actually actively keep the brain from changing.

So an adult brain not only loses its flexibility but suppresses it. This process may reflect the different agendas of adults and children. Children explore; adults exploit.

From an evolutionary perspective, childhood is an adaptation designed to let animals learn. Baby animals get a protected time when all they have to do is learn, without worrying about actually making things happen or getting things done. Adults are more focused on using what they already know to act effectively and quickly. Inhibitory chemicals may help in this process. Nature often works according to the maxim, “If it ain’t broke, don’t fix it.” In this case, there’s no need to change a brain that’s already working well.

In the new research, Jay Blundon and colleagues at St. Jude Children’s Research Hospital in Memphis, Tenn., tried to restore early-learning abilities to adult mice. As in the earlier experiments, they exposed the mice to a new sound and recorded whether their neurons changed in response. But this time the researchers tried making the adult mice more flexible by keeping the inhibitory brain chemicals from influencing the neurons.

In some studies, they actually changed the mouse genes so that the animals no longer produced the inhibitors in the same way. In others, they injected other chemicals that counteracted the inhibitors. (Caffeine seems to work in this way, by counteracting inhibitory neurotransmitters. That’s why coffee makes us more alert and helps us to learn.)

In all of these cases in the St. Jude study, the adult brains started to look like the baby brains. When the researchers exposed the altered adult mice to a new sound, their neurons responded differently, like babies’ neurons. The mice got better at discriminating among the sounds, too. The researchers also reversed the process, by getting young brains to produce the inhibitory chemicals—and the baby mice started acting like the adults.

The researchers suggest that these results may help in some disorders that come with aging. But should we all try to have childlike brains, perpetually sensitive to anything new? Maybe not, or at least not all of the time. There may be a tension between learning and acting, and adult brain chemistry may help us to focus and ignore distractions.

Babies of any species are surrounded by a new world, and their brain chemistry reflects that. Being a baby is like discovering love on your first visit to Paris after three double espressos. It’s a great way to be in some ways, but you might wake up crying at 3 in the morning. There is something to be said for grown-up stability and serenity.

HOW MUCH DO TODDLERS LEARN FROM PLAY?

Any preschool teacher will tell you that young children learn through play, and some of the best known preschool programs make play central, too. One of the most famous approaches began after World War II around the northern Italian city of Reggio Emilia and developed into a world-wide movement. The Reggio Emilia programs, as well as other model preschools like the Child Study Centers at Berkeley and Yale, encourage young children to freely explore a rich environment with the encouragement and help of attentive adults.

The long-term benefits of early childhood education are increasingly clear, and more states and countries are starting preschool programs. But, the people who make decisions about today’s preschool curricula often have more experience with elementary schools. As the early-childhood education researcher Erika Christakis details in her book “The Importance of Being Little,” the result is more pressure to make preschools like schools for older students, with more school work and less free play.

Is play really that important?

An April study in the journal Developmental Psychology by Zi Sim and Fei Xu of the University of California, Berkeley, is an elegant example of a new wave of play research. The researchers showed a group of 32 children, aged 2 and 3, three different machines and blocks of varying shapes and colors. The researchers showed the children that putting some blocks, but not others, on the machines would make them play music.

For half the children, the machines worked on a color rule—red blocks made the red machine go, for instance, no matter what shape they were. For the other children, the devices worked on a shape rule, so triangular blocks, say, made the triangle-shaped machine go.

Both sets of children then encountered a new machine, orange and L-shaped, and a new set of blocks. The toddlers trained with the color rule correctly used the orange block, while those trained with the shape rule chose the L-shaped block.

Next, the experimenter showed a different set of 32 toddlers the blocks and the machines and demonstrated that one block made one machine play music, without any instruction about the color or shape rules. Then she said, “Oh no! I just remembered that I have some work to do. While I’m doing my work, you can play with some of my toys!” The experimenter moved to a table where she pretended to be absorbed by work. Five minutes later she came back.

As you might expect, the toddlers had spent those five minutes getting into things—trying different blocks on the machines and seeing what happened. Then the experimenter gave the children the test with the orange L-shaped machine. Had they taught themselves the rules? Yes, the toddlers had learned the abstract color or shape rules equally well just by playing on their own.

It’s difficult to systematically study something as unpredictable as play. Telling children in a lab to play seems to turn play into work. But clever studies like the one in Developmental Psychology are starting to show scientifically that children really do learn through play.

The inspirational sayings about play you find on the internet—“play is the work of childhood” or “play is the best form of research,” for example—aren’t just truisms. They may actually be truths.

HOW MUCH SCREEN TIME IS SAFE FOR TEENS?

Almost every time I give a talk, somebody asks me how technology affects children. What starts out as a question almost always turns into an emphatic statement that technology is irreparably harming children’s development. The idea that computers, smartphones and videogames gravely harm young people runs deep in our culture.

I always give these worried parents the same answer: We won’t know for sure until we do careful, rigorous, long-term research. But the evidence that we already have, as opposed to anecdote and speculation, is reassuring.

A new paper in the journal Psychological Science by two British researchers, Andrew K. Przybylski at the University of Oxford and Netta Weinstein at the University of Cardiff, adds to the increasing number of studies suggesting that fears about technology are overblown. It reports on a study of more than 120,000 15-year-olds from the national pupil database of the U.K.’s Department for Education.

Anything you do in excess can be harmful. Things like smoking are harmful at any dose and become more so as doses rise. With smoking the advice is simple: Don’t. It’s different with eating, where to avoid harm we need to follow the Goldilocks principle: not too much or too little, but just right.

Researchers designed the new study to find out whether digital screen use was more like smoking or eating. They also set up the study to figure out what “too much” or “too little” might be, and how big an effect screen time has overall.

The questionnaire asked the participants to say how often they had experienced 14 positive mental states, like thinking clearly, solving problems well and feeling optimistic, energetic or close to other people. The questions covered the preceding two weeks, and replies were on a five-point scale ranging from none of the time to all of the time. The study used the teenagers’ own reports—a limitation—but their individual responses seemed to cohere, suggesting that they were generally accurate. Teens who reported getting less sleep, for instance, had lower overall scores for their mental well-being.

The teens independently reported how many hours they spent each day playing videogames, watching entertainment, using the computer for other reasons and using a smartphone screen. The researchers recorded the teens’ gender and ethnicity and used their postal codes to estimate their socioeconomic status.

The researchers then looked at the relationship between screen time and the answers to the questionnaire. After controlling for factors like gender, ethnicity and class, they found a Goldilocks effect. Up to a certain point screen time either positively correlated with mental well-being or showed no relationship to it. This fits with other studies showing that teens use computers and phones as a way to connect with other people.

The tipping point varied with how the children used their screens and whether they did it on weekdays or weekends, but the acceptable amount was fairly substantial—about 1½ to two hours a day of smartphone and computer use and three to four hours a day of videogames and entertainment. The teenagers often reported doing several of these things at once, but they clearly spent a fair amount of time in front of screens. When their screen time went beyond these bounds, it negatively correlated with mental well-being.

What’s more, screen time accounted for less than 1 percentage point of the variability in mental well-being. That’s less than a third as much as other factors like eating breakfast or getting enough sleep.

There are still lots of reasons for worrying about your teenager, of course. They’re at special risk for car accidents, suicide and gun violence. But, with a little common sense, screen time may not be among those perils.

Appeared in the March 18, 2017, print edition as 'The Goldilocks Solution for Teens And Their Screens.'

FLYING HIGH: RESEARCH UNVEILS BIRDS' LEARNING POWER

Shortly after I arrived at Oxford as a graduate student, intrigued by the new culture around me, I faced a very English whodunit. I had figured out how to get glass bottles of milk delivered to my doorstep—one of the exotic old-fashioned grace-notes of English domestic life. But every morning I would discover little holes drilled through the foil lids of the bottles.

Waking up early one day to solve the mystery, I saw a pretty little English songbird, the Great Tit, using its beak to steal my cream. It turned out that around 1920, Great Tits had learned how to drill for cream, and for the next 50 years the technique spread throughout England. (Why the dairies never got around to changing the tops remains an English mystery.)

How did these birds learn to steal? Could one bird have taught the others, like an ornithological version of the Artful Dodger in “Oliver Twist”? Until very recently, biologists would have assumed that each bird independently discovered the cream-pinching trick. Cultural innovation and transmission were the preserve of humans, or at least primates.

But new studies show just how many kinds of animals can learn from others—a topic that came up at the recent colloquium “The Extension of Biology Through Culture,” organized by the National Academy of Sciences in Irvine, Calif. There we heard remarkable papers that showed the extent of cultural learning in animals ranging from humpback whales to honeybees.

At the colloquium, Lucy Aplin of Oxford University reported on experiments, published in the journal Nature in 2015, with the very birds who stole my cream. Dr. Aplin and her colleagues studied the Great Tits in Wytham Woods near Oxford. Biologists there fitted out hundreds of birds, 90% of the population, with transponder tags, like bird bar codes, that let them track the birds’ movements.

Dr. Aplin showed the birds a feeder with a door painted half blue and half red. The birds lived in separate groups in different parts of the wood. Two birds from one group learned that when they pushed the blue side of the feeder from left to right, they got a worm. Another two birds from another group learned the opposite technique; they only got the worm when they pushed the red side from right to left. Then the researchers released the birds back into the wild and scattered feeders throughout the area. The feeders would work with either technique.

The researchers tracked which birds visited the feeders and at what time, as well as which technique they used. The wild birds rapidly learned by watching those trained in the lab. The blue-group birds pushed the blue side, while the red group pushed the red. And new birds who visited a feeder imitated the birds at that site, even though they could easily have learned that the other technique worked, too.

Then the researchers used a social-network analysis to track just which birds liked to hang out with which other birds. Like people on Facebook, birds were much more likely to learn from other birds in their social network than from birds they spent less time with. Also like humans, young birds were more likely to adopt the new techniques than older ones.

Most remarkably, the traditions continued into the next year. Great Tits don’t live very long, and only about 40% of the birds survive to the next season. But though the birds had gone, their discoveries lived on. The next generation of the blue group continued to use the blue technique.

We often assume that only animals who are closely related to us will share our cognitive abilities. The new research suggests that very different species can evolve impressive learning skills that suit their particular environmental niche. Great Tits—like honeybees, humpbacks and humans—are sophisticated foragers who learn to adapt to new environments. The young American graduate student and the young Great Tit at her door both learned to become masters of the British bottle.

THE BRAIN MACHINERY BEHIND DAYDREAMING

Like most people, I sometimes have a hard time concentrating. I open the file with my unwritten column and my mind stubbornly refuses to stay on track. We all know that our minds wander. But it’s actually quite peculiar. Why can’t I get my own mind to do what I want? What subversive force is leading it astray?

A new paper in Nature Reviews Neuroscience by Kalina Christoff of the University of British Columbia and colleagues (including the philosopher Zachary Irving, who is a postdoctoral fellow in my lab) reviews 20 years of neuroscience research. The authors try to explain how our brains make—and profit from—our wandering thoughts.

When neuroscientists first began to use imaging technology, they noticed something odd: A distinctive brain network lighted up while the subjects waited for the experiment to begin. The scientists called it “the default network.” It activated when people were daydreaming, woolgathering, recollecting and imagining the future. Some studies suggest that we spend up to nearly 50% of our waking lives in this kind of “task-unrelated thought”—almost as much time as we spend on tasks.

Different parts of the brain interact to bring about various types of mind-wandering, the paper suggests. One part of the default network, associated with the memory areas in the medial temporal lobes, seems to spontaneously generate new thoughts, ideas and memories in a random way pretty much all the time. It’s the spring at the source of that stream of consciousness.

When you dream, other parts of the brain shut down, but this area is particularly active. Neuroscientists have recorded in detail rats’ pattern of brain-cell activity during the REM (rapid eye movement) sleep that accompanies dreaming. Rat brains, as they dream, replay and recombine the brain activity that happened during the day. This random remix helps them (and us) learn and think in new ways.

Other brain areas constrain and modify mind-wandering—such as parts of our prefrontal cortex, the control center of the brain. In my case, this control system may try to pull my attention back to external goals like writing my column. Or it may shape my wandering mind toward internal goals like planning what I’ll make for dinner.

Dr. Christoff and colleagues suggest that creative thought involves a special interaction between these control systems and mind-wandering. In this activity, the control system holds a particular problem in mind but permits the brain to wander enough to put together old ideas in new ways and find creative solutions.

At other times, the article’s authors argue, fear can capture and control our wandering mind. For example, subcortical emotional parts of the brain, like the amygdala, are designed to quickly detect threats. They alert the rest of the brain, including the default network. Then, instead of turning to the task at hand or roaming freely, our mind travels only to the most terrible, frightening futures. Fear hijacks our daydreams.

Anxiety disorders can exaggerate this process. A therapist once pointed out to me that, although it was certainly true that the worst might happen, my incessant worry meant that I was already choosing to live in that terrible future in my own head, even before it actually happened.

From an evolutionary point of view, it makes sense that potential threats can capture our minds—we hardly ever know in advance which fears will turn out to be justified. But the irony of anxiety is that fear can rob us of just the sort of imaginative freedom that could actually create a better future.

OUR NEED TO MAKE AND ENFORCE RULES STARTS VERY YOUNG

Hundreds of social conventions govern our lives: Forks go on the left, red means stop and don’t, for heaven’s sake, blow bubbles in your milk. Such rules may sometimes seem trivial or arbitrary. But our ability to construct them and our expectation that everyone should follow them are core mechanisms of human culture, law and morality. Rules help turn a gang of individuals into a functioning community.

When do children understand and appreciate rules? Philosophers like Thomas Hobbes and Jean-Jacques Rousseau, as well as modern psychologists, have assumed that learning to follow social rules is really hard. For a pessimist like the 17th-century Hobbes, rules and conventions are all that keeps us from barbarous anarchy, and we learn them only through rigorous reward and punishment. For a romantic like the 18th-century Rousseau, children are naturally innocent and moral, and their development can only be distorted by the pressures of social convention.

For parents facing the milk-bubble issue, it can seem impossibly difficult to get your children to obey the rules (though you may wonder why you are making such a fuss about bubbles). But you also may notice that even a 3-year-old can get quite indignant about the faux pas of other 3-year-olds.

In a clever 2008 study, the psychologists Hannes Rakoczy, Felix Warneken and Michael Tomasello showed systematically how sensitive very young children are to rules. The experimenter told 3-year-olds, “This is my game, I’m going to dax” and then showed them an arbitrary action performed on an object, like pushing a block across a board with a stick until it fell into a gutter. Next, the experimenter “accidentally” performed another arbitrary action, like lifting the board until the block fell in the gutter, and said, “Oh no!”

Then Max the puppet appeared and said, “I’m going to ‘dax.’ ” He either “daxed” the “right” way with the stick or did it the “wrong” way by lifting the board, tipping it and dropping the block in the gutter directly. When the puppet did the wrong thing, violating the rules of the game, the children reacted by indignantly protesting and saying things like, “No, not like that!” or “Use the stick!”

Dr. Tomasello, working with Michael Schmidt and other colleagues, has taken these studies a step farther. The new research,which appeared this year in the journal Psychological Science, showed that young children are apt to see social rules and conventions even when they aren’t really there.

The children interpreted a single arbitrary action as if it were a binding social convention. This time the experimenter did not act as if the action were part of a game or say that he was “daxing.” He just did something arbitrary—for example, carefully using the flat piece at the end of a long stick to push a toy forward. Then the puppet either did the same thing or put the whole stick on top of the toy, pushing it forward. Even though the puppet reached the same goal using the second method, children protested and tried to get him to do things the experimenter’s way.

In a control condition, the experimenter performed the same action but gave the appearance of doing it by accident, fiddling with the stick without looking at the toy and saying “oops” when the stick hit the toy and pushed it forward. Now the children no longer protested when the puppet acted differently. They did not deduce a rule from the experimenter’s apparently accidental action, and they did not think that the puppet should do the same thing.

The Schmidt group argues that children are “promiscuously normative.” They interpret actions as conventions and rules even when that isn’t necessarily the case. Rules dominate our lives, from birth to death. Hobbes and Rousseau both got it wrong. For human beings, culture and nature are not opposing forces—culture is our nature.

WANT BABIES TO LEARN FROM VIDEO? TRY INTERACTIVE

Last week I was in Australia more than 7,000 miles away from my grandchildren, and I missed them badly. So, like thousands of other grandmothers around the world, I checked into FaceTime. My 11-month-old grandson looked back with his bright eyes and charming smile. Were we really communicating or was that just my grandmotherly imagination?

After all, there is a lot of research on the “video deficit”: Babies and young children are much less likely to learn from a video than from a live person. Judy DeLoache of the University of Virginia and colleagues, for example, looked at “baby media” in a study in the journal Psychological Science in 2011. Babies watched a popular DVD meant to teach them new words. Though they saw the DVD repeatedly, they were no more likely to learn the words than babies in a control group. But in live conversation with their parents, babies did learn the words.

Is the problem video screens in general? Or is it because little video-watchers aren’t communicating in real time with another person—as in a video chat?

We now have an answer that should bring joy to the hearts of distant grandparents everywhere. In a study published last month in the journal Developmental Science, Lauren Myers and colleagues at Lafayette College gave tablet computers to two groups of 1-year-olds and their families. In one group, the babies video-chatted on the tablet with an experimenter they had never seen before. She talked to them, read them a baby book with the chorus “peekaboo baby!” and introduced some new words. The other group watched a prerecorded video in which the experimenter talked and read a book in a similar way. For each group, the experiment took place six times over a week.

Babies in both groups watched the tablet attentively. But in the live group, they also coordinated their own words and actions with the actions of the experimenter, picking just the right moment to shout “peekaboo!” They didn’t do that with the video.

At the end of the week, the experimenter appeared in person with another young woman. Would the babies recognize their video partner in real life? And would they learn from her?

The babies who had seen the experimenter on prerecorded video didn’t treat her differently from the other woman and didn’t learn the new words. They did no better than chance on a comprehension test. But the babies who had interacted with the experimenter preferred to play with her over the new person. The older babies in the interactive group had also learned many of the new words. And the babies in the FaceTime group were significantly more likely to learn the “peekaboo” routine than the video-group babies.

These results fit with those of other studies. Babies seem to use “contingency”—the pattern of call and response between speaker and listener—to identify other people. In one classic experiment,Susan Johnson at Ohio State University and colleagues showed 1-year-olds a stylized robot (really just two fuzzy blobs on top of one another). Sometimes the robot beeped and lit up when the baby made a noise—it responded to what the baby did. Sometimes the robot beeped and lit up randomly, and then the top blob turned right or left. The babies turned their heads and followed the gaze of the robot when it was responsive, treating it like a person, but they ignored it when its movements had nothing to do with how the babies behaved.

Real life has much to be said for it, and many studies have shown that touch is very important for babies (and adults). But it’s interesting that what counts in a relationship, for all of us, isn’t so much how someone else looks or feels, or whether it’s 3-D grandmom or grandmom in Australia on a screen. What matters is how we respond to the other person and how they respond to us.

ALIENS RATE EARTH: SKIP THE PRIMATES, COME FOR THE CROWS

What makes human beings so special? In his new book on animal intelligence, the primatologist Frans de Waal shows that crows and chimps have many of the abilities that we once thought were uniquely human—like using tools and imagining the future. So why do we seem so different from other animals?

One theory is that when Homo sapiens first evolved, some 200,000 years ago, we weren’t that different: We were just a little better than other primates at cultural transmission, at handing new information on to the next generation. Our human success is the result of small, cumulative, cultural changes over many generations rather than of any single great cognitive leap.

For the first 150,000 years or so of our existence, isolated groups of humans occasionally made distinctive innovations—for example, creating jewelry out of shells. But those innovations didn’t stick. It was only around 50,000 years ago, barely yesterday in evolutionary time, that a critical mass of humans initiated the unending cascade of inventions that shapes our modern life for good and ill.

I thought about this as I read (and reread and reread) “The Early Cretaceous” to my dinosaur-obsessed 4-year-old grandson, Augie. Unlike Augie, I just couldn’t concentrate on the exact relationship between the Deinonychus and the Carcharodontosaurus. My eyelids drooped and my mind began to wander. What would an alien biologist make of the history of life on Earth across time...?

Dept. of Biology, University of Proxima Centauri

Terran Excursion Field Report

[75,000 B.C.]: I have tragic news. For the last hundred million years I’ve returned to this planet periodically to study the most glorious and remarkable organisms in the universe—the dinosaurs. And they are gone! A drastic climate change has driven them to extinction.

Nothing interesting is left on this planet. A few animals have developed the ability to use tools, think abstractly and employ complicated vocal signals. But however clever the birds may be, they are still puny compared with their dinosaur ancestors.

A few species of scruffy primates also use tools and pass on information to their young. But it’s hard to tell these species apart. Some are preoccupied with politics [early chimp ancestors?], while others mostly seem to care about engaging in as much energetic and varied sex as possible [early bonobos?]. And then there are the ones who are preoccupied with politics, sex and trinkets like shell necklaces [that would be us].

But there is nothing left even remotely as interesting as a giganotosaurus.

[A.D. 2016]: Something may be happening on Earth. Judging from radio signals, there is now some form of intelligent civilization, a few traces of science and art—although most of the signals are still about politics, sex and trinkets. I can’t really imagine how any of those primitive primate species could have changed so much, so quickly, but it might be worth accelerating my next visit.

[A.D. 500,000]: Good news! After another dramatic climate change and a burst of radiation, the primates are gone, an evolutionary eye-blink compared with the 180-million-year dinosaur dynasty.

But that extinction made room for the crows to really flourish. They have combined superior intelligence and the insane cool of their dinosaur ancestors. Those earlier radio signals must have been coming from them, and the planet is now full of the magnificent civilization of the Early Corvidaceous. I look forward to my next visit….

As the book drops from my hands, I shake myself awake—and hold on to Augie a little tighter.

YOUNG MICE, LIKE CHILDREN, CAN GROW UP TOO FAST

Is it good to grow up? We often act as if children should develop into adults as quickly as possible. More and more we urge our children to race to the next level, leap over the next hurdle, make it to the next grade as fast as they can. But new brain studies suggest that it may not be good to grow up so fast. The neuroscientist Linda Wilbrecht at my own school, the University of California, Berkeley, and her collaborators recently reported that early stress makes babies, at least baby mice, grow up too soon.

In an experiment published in 2011 in the journal Developmental Cognitive Neuroscience, Dr. Wilbrecht and a colleague discovered that young mice learn more flexibly than older ones. The researchers hid food at one of four locations in a pile of shavings, with each location indicated by a different smell. The mice quickly learned that the food was at the spot that smelled, say, like thyme rather than cloves, and they dug in the shavings to find their meal. The experimenters then reversed the scents: Now the clove-scented location was the correct one.

To solve this problem the mice had to explore a new possibility: They had to dig at the place with the other smell, just for the heck of it, without knowing whether they would find anything. Young mice were good at this kind of exploratory, flexible “reversal learning.”

But at a distinct point, just as they went from being juveniles to adults, they got worse at solving the problem. Instead, they just kept digging at the spot where they had found the food before. The experiment fit with earlier studies: Like mice, both young rats and young children explore less as they become adults.

The change happened when the mouse was between 26 and 60 days old, and it was connected to specific brain changes. Life is compressed for mice, so the time between 26 days and 60 days is like human adolescence.

In the new experiment, published in 2015 in the same journal, the researchers looked at how the young mice reacted to early stress. Some of the mice were separated from their mothers for 60 or 180 minutes a day, although the youngsters were kept warm and fed just like the other mice. Mice normally get all their care from their mother, so even this brief separation is very stressful.

The stressed mice actually developed more quickly than the secure mice. As adolescents they looked more like adults: They were less exploratory and flexible, and not as good at reversal learning. It seemed that they grew up too fast. And they were distinctive in another way. They were more likely to drink large quantities of ethanol—thus, more vulnerable to the mouse equivalent of alcoholism.

These results fit with an emerging evolutionary approach to early stress. Childhood is a kind of luxury, for mice as well as men, a protected period in which animals can learn, experiment and explore, while caregivers look after their immediate needs.

Early stress may act as a signal to animals that this special period is not a luxury that they can afford—they are in a world where they can’t rely on care. Animals may then adopt a “live fast, die young” strategy, racing to achieve enough adult competence to survive and reproduce, even at the cost of less flexibility, fewer opportunities for learning and more vulnerability to alcohol.

This may be as true for human children as it is for mouse pups. Early life stress is associated with earlier puberty, and a 2013 study by Nim Tottenham and colleagues in the Proceedings of the National Academy of Sciences found that children who spent their early years in orphanages prematurely developed adultlike circuitry in the parts of the brain that govern fear and anxiety.

Care gives us the gift of an unhurried childhood.

TO CONSOLE A VOLE: A RODENT CARES FOR OTHERS

One day when I was a young professor, a journal rejected a paper I had submitted, a student complained about a grade, and I came home to find that I had forgotten to take anything out for dinner. Confronted by this proof of my complete failure as both an academic and a mother, I collapsed on the sofa in tears. My son, who was just 2, looked concerned and put his arms around me. Then he ran and got a box of Band-Aids.

Even 2-year-olds will go out of their way to console someone in distress—it’s a particularly touching demonstration of basic human kindness. But is kindness exclusively human? A new study in the journal Science by J.P. Burkett at Emory University and colleagues suggests that consolation has deep evolutionary roots and is connected to empathy and familial love.

Chimpanzees, wolves, crows and elephants will console another animal. When one chimp attacks another, for instance, a third party will often try to comfort the victim. But these are all very intelligent animals with complex social structures. Do you need to be smart to be kind?

The new study looked at two species of voles—not terribly smart rodents with a relatively simple social structure. One species, the prairie vole, has strong “pair bonds.” The mother and father voles raise babies together, and they are “socially monogamous”—that is, they mostly mate and spend time with each other instead of other voles. The other species, the meadow vole, is similar to its prairie cousin in many ways, including general intelligence, but meadow voles don’t pair-bond, and the males don’t take care of babies. Do you need to be smart to be kind?

In the Burkett experiment, one vole behind a transparent barrier watched another either undergoing stress or just sitting there. Then the glass was removed.

A prairie-vole observer would provide more licking and grooming—the vole equivalent of a warm hug—if the other vole had been stressed. This consoled the stressed prairie vole, which became less anxious. The meadow voles, by contrast, didn’t console each other.

The prairie voles seemed to empathize with their stressed companions. When a prairie vole saw another in trouble, it got anxious itself, and its stress hormones increased. (You might wonder if grooming others is just an automatic reaction to stress, direct or indirect. But the voles who experienced stress directly didn’t try to groom the observers.)

In voles, and probably in humans too, the hormone oxytocin plays a big role in social bonds. In many mammals, oxytocin helps to create the bond between mothers and babies. Oxytocin spikes when you go into labor. But in a few species, including prairie voles and us (but not, apparently, meadow voles), this system has been co-opted to make adults love each other, too. When the researchers administered a chemical that blocks oxytocin, the prairie voles stopped consoling others.

Providing consolation didn’t seem to depend on gender, and the prairie voles consoled familiar voles, not just mates or relations. But, in another parallel to humans, the voles didn’t reach out to strangers.

Of course, humans, even at 2, understand others more deeply than voles do, and so can provide consolation in more complicated ways. And chimpanzees and bonobos, who do console, don’t pair-bond, though they do have other strong social bonds. (Bonobos often console others by having sex with them, including homosexual sex.)

But the new study does suggest that the virtue of kindness comes more from the heart than the mind, and that it is rooted in the love of parents and children.

GIVING THANKS FOR THE INNOVATION THAT SAVES BABIES

Every year at this time, I have a special reason to be thankful. My bright, pretty, granddaughter Georgiana turned 2 a few days ago. She’s completely healthy—and accomplished too: She can sing most of “Twinkle, Twinkle Little Star” and does an impressive cow imitation.

I’m especially thankful for these ordinary joys, because Georgie has a small genetic mutation that leads to a condition called Congenital Melanocytic Nevus. The main symptom is a giant mole, or nevus, that covers much of her back. CMN also puts children at risk for other problems including skin cancer and brain damage. As Francis Bacon said, “He that hath wife and children hath given hostages to fortune.” But a child with CMN, or myriad other genetic conditions, makes you especially aware of how infinitely vulnerable and infinitely valuable all children are.

Georgie makes me grateful for other human gifts, too. Right now CMN can’t be cured. But the distinctively human adventurers we call scientists are perpetually exploring the frontiers of knowledge.

My colleague Jennifer Doudna at the University of California, Berkeley has helped develop a technique called CRISPR for modifying genes (the latest paper about it is in the new issue of Science). Like many breakthroughs, the discovery was an unexpected side effect of pure, basic science research—that quintessential expression of our human curiosity. The new techniques have risks: Dr. Doudna has argued that we need to strictly regulate this research. But they also hold the promise of treating genetic conditions like CMN.

This Thanksgiving I’m thankful for another miracle and another amazing, distinctively human ability that allowed it to take place. Atticus, Georgie’s little brother, was born three months ago. Attie’s mom had preeclampsia, a dangerous spike in blood pressure during pregnancy. The only treatment is delivery, so Attie was delivered a month early and spent a couple of days in the Neonatal Intensive Care Unit. After a few months of constant eating, he is as plump and bright-eyed a baby as you could ask for.

The banality of the phrase “spent a couple of days in the NICU” captures the other human gift. Attie’s treatment seemed completely routine and unremarkable. The nurses put him in an incubator with a breathing tube, no innovation or genius required. But a hundred years ago the idea that a premature baby could thrive was as cutting-edge as gene therapy seems now. (Lady Sybil on the series “Downton Abbey” dies of preeclampsia.)

The first early 20th-century incubators were so futuristic that they were exhibited at Luna Park in Coney Island. In the 1930s scientists discovered how to give babies oxygen. But as with CRISPR now, there were perils—at first doctors used too much oxygen, which blinded thousands of babies. Further scientific advances mean that today a premature baby who once had a 95% chance of dying now has a 95% chance of living.

Blind, random biological forces created Georgie’s CMN. But those same forces also created a new species, homo sapiens, who could do two things especially well. Humans could innovate—discovering features of the world and inventing tools to change it. And they could imitate: Each generation could quickly and easily take on the discoveries of the last. This combination means that innovators like Dr. Doudna can make discoveries that become just ordinary for the next generation. So today I am profoundly grateful for both the rare scientific genius that gives hope for babies like Georgie and the commonplace medical routine that saves babies like Attie.

NO, YOUR CHILDREN AREN'T BECOMING DIGITAL ZOMBIES

The other day, a newspaper writer joined the chorus of angry voices about the bad effects of new technology. “There can be no rational doubt that [it] has caused vast injury.” It is “superficial, sudden, unsifted, too fast for the truth.” The day was in 1858, and the quote was about the telegraph. Similarly, the telephone, radio and television have each in turn been seen as a source of doom.

Mobile devices like smartphones are just the latest example. Parents fear that they will make teenagers more socially alienated and disconnected—worries echoed and encouraged by many journalists and writers. Since all those earlier technologies turned out to be relatively harmless, why are we so afraid?

One reason may be the inevitable lag between when a technology emerges and when we can assess its consequences. That’s especially true when we’re concerned about a new technology’s influence on the next generation. Meanwhile, anxiety and anecdotes proliferate. An old saw in statistics is that the plural of anecdote is not “data”—but it may well be “op-ed article.”

In a paper coming out in November in the journal Perspectives in Psychological Science, Madeleine George and Candice Odgers at Duke University review the scientific evidence we have so far about the effects of social media on adolescents. They found that teenagers are indeed pervasively immersed in the digital world. In one survey, teenagers sent an average of 60 texts a day, and 78% of them owned an Internet-connected mobile phone.

But the researchers also found little evidence to support parents’ fears. Their conclusion is that teenagers’ experience in the mobile world largely parallels rather than supplants their experience in the physical world. Teenagers mostly use mobile devices to communicate with friends they already know offline. They can have bad online experiences, but they are the same sort of bad experiences they have offline.

Two large-scale surveys done in 2007 and 2013 in the Netherlands and Bermuda, involving thousands of adolescents, found that teenagers who engaged in more online communication also reported more and better friendships, and smaller studies bear this out as well. There is no sign at all that friendships have changed or suffered as mobile use has risen.

The George-Odgers team cataloged parents’ biggest fears about mobile technology—that it might alienate children from parents, for example, or make them vulnerable to strangers—and found little evidence to support them. The researchers did find that screens seem to have a genuinely disruptive effect on sleep, whether caused by the effects of LED light or by social excitement. So it’s a good idea to keep your children (and yourself) from stowing the phone bedside.

The researchers also emphasize the inevitable limitations of existing studies, since these issues have arisen so recently. But the research we do have already is more reassuring than alarming.

So why, despite the research and all those failed previous prophecies of technological doom, are people so convinced that this time it’s different? One reason may be that the experience of technological and cultural change differs for adults and children. Psychologists call it “the cultural ratchet.” Each generation of children easily and automatically takes on all the technologies of the previous generations. But each generation also introduces technologies, and mastering them as an adult is much more difficult.

The latest click of the ratchet is so vivid that the regularities of history are hard to see. Inevitably, the year before you were born looks like Eden, and the year after your children were born looks like “Mad Max.”

BABIES MAKE PREDICTIONS, TOO

In “The Adventure of Silver Blaze,” about a valuable racehorse that mysteriously disappears, Sherlock Holmes tells the hapless Detective Gregory to note the curious incident of the dog in the nighttime. But, says Gregory, the dog did nothing in the nighttime. That was the curious incident, Holmes replies—the dog didn’t bark on the night of the crime, as you would expect. A new study suggests that as babies start to figure out the world, they think a lot like Sherlock.

People often say that babies are “sponges.” The metaphor reflects a common picture of how the brain works: Information floods into our eyes and ears and soaks into our brains, gradually becoming more abstract and complex. This image of the brain is vividly captured in the “abstract thought zone” of the recent animated Pixar movie “Inside Out”—where three-dimensional experiences are transformed into flat cubist ideas.

But a very different picture, called “predictive coding,” has been making a big splash in neuroscience lately. This picture says that most of the action in the brain comes from the top down. The brain is a prediction machine. It maintains abstract models of the world, and those abstract models generate predictions about what we will see and hear. The brain keeps track of how well those predictions fit with the actual information coming into our eyes and ears, and it notes discrepancies.

If I see something that I didn’t predict, or if I don’t see something that I did predict, my brain kicks into action. I modify my abstract model of the world and start the process over.

If “predictive coding” is right, we’re designed to perceive what doesn’t happen as much as what does. That may sound bizarre, but think about an Alfred Hitchcock movie. You are riveted by a scene where absolutely nothing is happening, because you are expecting the killer to pounce at any second. Or think about a man who lives by the train tracks and wakes up with a start when the train doesn’t come by on time.

In fact, studies show that your brain responds to the things that don’t happen, as well as those that do. If we expect to see something and it doesn’t appear, the visual part of our brain responds. That makes sense for adults, with all our massive accumulated learning and experience. But how about those baby sponges?

In a new paper in the Proceedings of the National Academy of Sciences, Richard Aslin of the University of Rochester and colleagues report on a new study of 6-month-old babies’ brain activity. They used a technique called NIRS, or Near Infrared Spectrometry. It records whether the brain is active in the occipital area, where visual pictures are processed, or in the temporal area, where sounds go.

In a control experiment, babies just heard a honking sound or saw a cartoon face emerge on a screen. Sure enough, the visual area lit up when the babies saw the face but not when they heard the sound.

Then, with another group of babies, the experimenters repeatedly played the honk and showed the image of the face right afterward. The babies started to predict that the face would show up when they heard the sound.

That’s when the experimenters arranged for something unexpected to happen: The babies heard the honking sound, but the face did not then appear.

If the babies were just sponges, nothing special should happen in their brains; after all, nothing had happened in the outside world. But if they were using predictive coding, they should respond to the unexpected event. And that’s what happened—the visual area lit up when the babies didn’t see the picture they had expected. In fact, it activated just as much as when the babies actually did see the picture.

In this way, the babies were more like scientists than like sponges. Even 6-month-olds, who can’t crawl or babble yet, can make predictions and register whether the predictions come true, as the predictive coding picture would suggest.

It turns out that baby brains are always on the lookout for the curious incident of the dog who did nothing. Each one is a little Sherlock Holmes in the making.

SMARTER EVERY YEAR? MYSTERY OF THE RISING IQS

Are you smarter than your great-grandmom? If IQ really measures intelligence, the answer is probably a resounding “yes.”

IQ tests are “normed”: Your score reflects how you did compared with other people, like being graded on a curve. But the test designers, who set the average in a given year at 100, have to keep “renorming” the tests, adding harder questions. That’s because absolute performance on IQ tests—the actual number of questions people get right—has greatly improved over the last 100 years. It’s called the Flynn effect, after James Flynn, a social scientist at New Zealand’s University of Otago who first noticed it in the 1980s.

How robust is the Flynn effect, and why has it happened? In the journal Perspectives in Psychological Science, Jakob Pietschnig and Martin Voracek at the University of Vienna report a new “meta-analysis.” They combined data from 271 studies, done from 1909 to 2013, testing almost four million people from 31 countries on six continents. Most of the test questions remain the same over time, so the scientists could look at how much people improved from decade to decade.

They found that the Flynn effect is real—and large. The absolute scores consistently improved for children and adults, for developed and developing countries. People scored about three points more every decade, so the average score is 30 points higher than it was 100 years ago.

The speed of the rise in scores varied in an interesting way. The pace jumped in the 1920s and slowed down during World War II. The scores shot up again in the postwar boom and then slowed down again in the ’70s. They’re still rising, but even more slowly. Adult scores climbed more than children’s.

Why? There are a lot of possible explanations, and Drs. Pietschnig and Voracek analyze how well different theories fit their data. Genes couldn’t change that swiftly, but better nutrition and health probably played a role. Still, that can’t explain why the change affected adults’ scores more than children’s. Economic prosperity helped, too—IQ increases correlate significantly with higher gross domestic product.

The fact that more people go to school for longer likely played the most important role—more education also correlates with IQ increases. That could explain why adults, who have more schooling, benefited most. Still, the Flynn effect has a strong impact on young children. Education, just by itself, doesn’t seem to account for the whole effect.

The best explanation probably depends on some combination of factors. Dr. Flynn himself argues for a “social multiplier” theory. An initially small change can set off a benign circle that leads to big effects. Slightly better education, health, income or nutrition might make a child do better at school and appreciate learning more. That would motivate her to read more books and try to go to college, which would make her even smarter and more eager for education, and so on.

“Life history” is another promising theory. A longer period of childhood correlates with better learning abilities across many species. But childhood is expensive: Someone has to take care of those helpless children. More resources, nutrition or health allow for a longer childhood, while more stress makes childhood shorter. Education itself really amounts to a way of extending the childhood learning period.

But are you really smarter than your great-grandmom? IQ tests measure the kind of intelligence that makes you do well at school. If we had tests for the kind of intelligence that lets you run a farm, raise eight children and make perfect biscuits on a smoky wood stove, your great-grandmom might look a lot smarter than you do.

The thing that really makes humans so smart, throughout our history, may be that we can invent new kinds of intelligence to suit our changing environments.

THE MYSTERY OF LOYALTY, IN LIFE AND ON 'THE AMERICANS'

A few weeks ago, I gave a talk at the American Philosophical Association, in an excellent, serious symposium on human experience and rationality. The only problem was that my appearance meant missing the brilliant, addictive TV series “The Americans.” Thank heavens for on-demand cable—otherwise the temptation to skip the conference and catch up on the latest betrayals and deceptions might have been too much for me.

Still, one practical benefit of a philosophical education is that it helps you to construct elaborate justifications for your favorite vices. So I’d argue that “The Americans” tackles the same philosophical questions I wrestled with in my talk. Loyalty—our specific, personal commitment to a particular child, lover or country—is one of the deepest human emotions. But is it compatible with reason? And is it morally profound or morally problematic?

The TV show, on FX, is about an apparently ordinary suburban married couple in the 1980s, devoted to each other and their children. But, unknown even to their offspring, they are actually high-level Soviet spies, sent to the U.S. secretly 20 years before. Between making lunches and picking up the children from school, they put on weird disguises, seduce strangers and commit elaborate murders, all out of loyalty to the Soviet empire—and in doing so, they suffer agonies of conflict.

Where does loyalty come from? Many mammals have developed special brain systems, involving the neurochemical oxytocin, to regulate what psychologists call “attachment”—what the rest of us simply call love.

Attachment is a profound but strange emotion. We can be loyal to a particular child, lover or country, regardless of what they are actually like—just because they’re ours. Most social relationships are reciprocal, with benefits for both parties. But we can and should be loyal, even if we gain nothing in return.

The attachment system originally evolved to get mammalian mothers to protect their helpless babies. Mother love really is as fundamental to evolution as it is to storytelling. Still, is that profound biological impulse to protect this one special child enough to justify deceiving her or committing violence against others? If, as in the recently concluded Season 3 of “The Americans,” a mother deeply loves her daughter (who has no idea that her mom is a Soviet spy), should the mother try to make sure her child never finds out? Or should she teach her daughter how she, too, might wear ridiculous wigs effectively and assassinate enemies?

Evolution has also co-opted the attachment system to produce other kinds of love. In a few species, like prairie voles, the attachment system extends to fathers. The male voles also care for their babies, and they “pair-bond” with their mates. Systematic experiments show that oxytocin plays an important role in this kind of love, too.

Lust is as ubiquitous in biology as it is on the FX channel. But only a few mammals, including both prairie voles and Philip and Elizabeth Jennings—the quintessentially human couple in “The Americans”—combine lust with love and loyalty.

How do you maintain a loyal pair bond, given the conflicting demands of loyalty to a career and the possibility of other loves? Particularly when, as in Season 3, that career requires you to systematically seduce FBI secretaries and the teenage daughters of State Department officials?

Mice are loyal to their pups and prairie voles to their mates. But only human beings are also loyal to communities, to countries, to ideologies. Humans have come to apply the attachment system far more broadly than any other creature; a whiff of oxytocin can even make us more likely to trust strangers and cooperate with them. That broader loyalty, combined with our human talent for abstraction, is exactly what makes countries and ideologies possible.

So here’s the deepest philosophical question of “The Americans,” one that doesn’t just arise in fiction. Can loyalty to a country or an idea ever justify deception and murder?

HOW CHILDREN DEVELOP THE IDEA OF FREE WILL

We believe deeply in our own free will. I decide to walk through the doorway and I do, as simple as that. But from a scientific point of view, free will is extremely puzzling. For science, what we do results from the causal chain of events in our brains and minds. Where does free will fit in?

But if free will doesn’t exist, why do we believe so strongly that it does? Where does that belief come from? In a new study in the journal Cognition, my colleagues and I tried to find out by looking at what children think about free will. When and how do our ideas about freedom develop?

Philosophers point out that there are different versions of free will. A simple version holds that we exercise our free will when we aren’t constrained by outside forces. If the door were locked, I couldn’t walk through it, no matter how determined I was. But since it’s open, I can choose to go through or not. Saying that we act freely is just saying that we can do what we want when we aren’t controlled by outside forces. This poses no problem for science. This version simply says that my actions usually stem from events in my brain—not from the world outside it.

But we also think that we have free will in a stronger sense. We aren’t just free from outside constraints; we can even act against our own desires. I might want the cookie, believe that the cookie is delicious, think that the cookie is healthy. But at the last moment, as a pure act of will, I could simply choose not to eat the cookie.

In fact, I can even freely choose to act perversely. In Dostoyevsky’s “Crime and Punishment,” Raskolnikov murders an old woman—a stupid, brutal, unnecessary crime—just to show that he truly has free will. This idea of pure autonomy is more difficult to reconcile with the scientific view that our actions are always caused by the events in our minds and brains.

Where does this Raskolnikovian idea of free will come from? Does it point to a mysterious phenomenon that defies science? Or do we construct the idea to explain other aspects of our experience?

Along with Tamar Kushnir and Nadia Chernyak at Cornell University and Henry Wellman at the University of Michigan, my lab at the University of California, Berkeley, set out to see what children age 4 and 6 think about free will. The children had no difficulty understanding the first sense of free will: They said that Johnny could walk through the doorway, or not, if the door was open, but he couldn’t go through a closed door.

But the 4-year-olds didn’t understand the second sense of free will. They said that you couldn’t simply decide to override your desires. If you wanted the cookie (and Mom said it was OK), you would have to eat it. The 6-year-olds, in contrast, like adults, said that you could simply decide whether to eat the cookie or not, no matter what. When we asked the 6-year-olds why people could act against their desires, many of them talked about a kind of absolute autonomy: “It’s her brain, and she can do what she wants” or “Nobody can boss her around.”

In other studies, in the journal Cognitive Science, Drs. Kushnir and Chernyak found that 4-year-olds also think that people couldn’t choose to act immorally. Philosophers and theologians, and most adults, think that to be truly moral, we have to exercise our free will. We could do the wrong thing, but we choose to do the right one. But the 4-year-olds thought that you literally couldn’t act in a way that would harm another child. They didn’t develop the adult concept until even later, around 8.

We don’t simply look into our minds and detect a mysterious free will. This research suggests, instead, that children develop the idea of free will to explain the complex, unpredictable interactions among all our conflicting desires, goals and moral obligations.

LEARNING FROM KING LEAR: THE SAVING GRACE OF LOW STATUS

Last week I saw the great Canadian actor Colm Feore brilliantly play King Lear. In one of the most heart-wrenching scenes, Lear, the arrogant, all-powerful king, humiliated by his daughters, faces the fury of the storm on the heath. Yet he thinks not about himself but the “poor naked wretches” whose “houseless heads and unfed sides” he has ignored before.

“Oh I have ta’en too little care of this!
Take physic, pomp.
Expose thyself to feel what wretches feel,
That thou mayst shake the superflux to them
And show the heavens more just.”

As usual Shakespeare’s psychology was uncannily accurate. You might think that losing status would make us more selfish. But, in fact, a new study in the Proceedings of the National Academy of Sciences by Ana Guinote at University College London and colleagues shows just the opposite. When people feel that they are more powerful, they are less likely to help others; when they “feel what wretches feel,” they become more altruistic.

In the new paper, the researchers artificially manipulated how people felt about their place in the pecking order. They randomly told some students that their department was one of the best in the university and told others that it was one of the worst. At the very end of the session, allegedly after the experiment was over, the experimenter “accidentally” dropped a box full of pens on the floor. The researchers recorded how many pens the students picked up and handed back. The students whose departmental pride had been squashed picked up more pens than the top dogs.

In another study included in the paper, the experimenters manipulated status temporarily in a similar way and asked the students about their values and life goals. The low-status students talked about altruistic goals, such as helping others, more than the high-status students did.

In a third study, the experimenters randomly told the students that they belonged to a group who had scored high or low on an arbitrary test. Then the students had a discussion with a group of other students about how to pick an apartment and a roommate. Independent coders analyzed their behavior (the coders didn’t know about the status manipulation). The “low-status” students displayed more signals of niceness and cooperation: They smiled more and acted more warmly and empathically toward the other person. The “high-status” students were more focused on displaying their own competence and knowledge.

The researchers even got similar results with children age 4 and 5. They were asked to share stickers with another child. The more dominant the children were, the less they shared.

Why would this happen? Dr. Guinote and her colleagues suggest that, in a hierarchical group, low-status people have to use other strategies to accomplish their goals. Mutual helpfulness, cooperation and altruism are ways to counteract the simpler and more obvious advantages of wealth and rank.

You can even see this in chimpanzees. If several lower-ranked chimps get together, they can overturn even the most impressive alpha male.

What’s interesting is that nothing about the students made them intrinsically nice or mean—the only difference was their brief, immediate experience of high or low status. But these results may help to explain the results of other studies showing that people with more wealth or rank or power are less helpful, in general. When people are perpetually reminded of their high status, they seem to become less concerned about others.

The PNAS study and “King Lear” together suggest a modern way to “physic pomp.” The King, at least in Shakespeare, has his Fool to remind him of his true status. Perhaps we should have a “fool app” that periodically pings to remind us that we are all just “poor, bare, forked animals” after all.

THE DANGERS OF BELIEVING THAT TALENT IS INNATE

In 2011, women made up half the professors of molecular biology and neuroscience in the U.S. but less than a third of the philosophy professors. How come? Is it because men in philosophy are biased against women or because women choose not to go into philosophy? But why would philosophers be more biased than molecular biologists? And why would women avoid philosophy and embrace neuroscience?

A new paper in the journal Science suggests an interesting answer. Sarah-Jane Leslie, a philosopher at Princeton University, Andrei Cimpian, a psychologist at the University of Illinois, and colleagues studied more than 1,800 professors and students in 30 academic fields. The researchers asked the academics how much they thought success in their field was the result of innate, raw talent. They also asked how hard people in each field worked, and they recorded the GRE scores of graduate students.

Professors of philosophy, music, economics and math thought that “innate talent” was more important than did their peers in molecular biology, neuroscience and psychology. And they found this relationship: The more that people in a field believed success was due to intrinsic ability, the fewer women and African-Americans made it in that field.

Did the fields with more men require more intelligence overall? No, the GRE scores weren’t different, and it seems unlikely that philosophers are smarter than biologists or neuroscientists. Did the fields with more men require more work? That didn’t make a difference either.

Was it because those fields really did require some special innate genius that just happened to be in short supply in women and African-Americans? From a scientific perspective, the very idea that something as complicated as philosophical success is the result of “innate talent” makes no sense. For that matter, it also makes no sense to say that it’s exclusively the result of culture.

From the moment a sperm fertilizes an egg, there is a complex cascade of interactions between genetic information and the environment, and once a baby is born, the interactions only become more complex. To ask how much innate talent you need to succeed at philosophy is like asking how much fire, earth, air and water you need to make gold. That medieval theory of elements just doesn’t make sense any more, and neither does the nature/nurture distinction.

But although scientists have abandoned the idea of innate talent, it’s still a tremendously seductive idea in everyday life, and it influences what people do. Psychologist Carol Dweck at Stanford has shown in many studies, summarized in her book “Mindset,” that believing in innate academic talent has consequences, almost all bad. Women and minorities, who are generally less confident to begin with, tend to doubt whether they have that mythical magic brilliance, and that can discourage them from trying fields like math or philosophy. But the idea is even bad for the confident boy-genius types.

In Dr. Dweck’s studies, students who think they are innately smart are less likely to accept and learn from mistakes and criticism. If you think success is the result of hard work, then failure will inspire you to do more. If failure is an existential threat to your very identity, you will try to deny it.

But these studies say something else. Why are there so few women in philosophy? It isn’t really because men are determined to keep them out or because women freely choose to go elsewhere. Instead, as science teaches us again and again, our actions are shaped by much more complicated and largely unconscious beliefs. I’m a woman who moved from philosophy to psychology, though I still do both. The new study may explain why—better than all the ingenious reasons I’ve invented over the years.

The good news, though, is that such beliefs can change. Dr. Dweck found that giving students a tutorial emphasizing that our brains change with effort and experience helped to shift their ideas. Maybe that would be a good exercise for the philosophers, too.

WHY DIGITAL-MOVIE EFFECTS STILL CAN'T DO A HUMAN FACE

Last month in New Zealand I visited some of the wizardly artists and engineers working for Weta Digital, the effects company behind series like “The Hobbit” and “Planet of the Apes.” That set me thinking about how we decide whether something has a mind.

You might not imagine that your local multiplex would be a font of philosophical insight. But the combination of Alan Turing ’s “imitation game” (the idea behind the new movie’s title) and the latest digital effects blockbusters speaks to deep questions about what it means to be human.

Turing, who helped to invent the modern computer, also proposed that the best test of whether a computer could think was the imitation game. Someone would sit at a keyboard interacting with either a computer or another human at the other end. If the person at the keyboard couldn’t tell the difference between the two, then you would have to accept that the computer had achieved human intelligence and had something like a human mind.

But suppose that, instead of sitting at a keyboard, you were looking at a face on a screen? That imitation-game test, it turns out, is much, much harder for a computer to pass.

Nowadays computers can generate convincing images of almost everything—from water on fur to wind in the grass. Except a human face. There they stumble on the problem of the “uncanny valley”—the fact that there is nothing creepier than something that is almost human. Human beings are exquisitely attuned to the subtleties of emotion that we see in the faces and movements of others.

As a result, when filmmakers do manage to generate digital faces, they have to do it by using humans themselves. Characters like the Na’vi in “Avatar” or Caesar in “Planet of the Apes” heavily depend on “motion capture.” The filmmakers take a real actor’s performance and record the movements the actor makes in detail. Then they reproduce those movements on the face of a character.

More-traditional computer animation also relies on real people. Animators are really actors of a kind, and the great animated films from “Snow White” to” Toy Story” have relied on their skills. Pixar (which my husband co-founded) hires animators based more on their understanding of acting than on their drawing. A great actor imagines how a character’s face and body would move, and then makes his own face and body move the same way. Great animators do the same thing, but they use a digital interface to produce the movements instead of their own eyes and arms. That’s how they can turn a teapot or a Luxo lamp into a convincing character.

Our ability to detect emotion is as wide-ranging as it is sensitive. We notice the slightest difference from a human face, but we can also attribute complex emotions to teapots and lamps if they move just the right way.

Mark Sagar, who helped to design the faces in “Avatar” before becoming a professor at the University of Auckland, has created one of the most convincing completely computer-generated faces: an infant that he calls Baby X. To do this he has to use a model that includes precise information about the hundreds of muscles in our faces and their relation to our facial expressions. He is trying to integrate the latest neuroscience research about the human brain into his model. For a computer to simulate a human face, it has to simulate a human brain and body, too.

It made sense to think that the ability to reason and speak was at the heart of the human mind. Turing’s bet was that a computer that could carry on a conversation would be convincingly human. But the real imitation game of digital-effects movies suggests that the ability to communicate your emotions may be even more important. The ineffable, subtle, unconscious movements that tell others what we think and feel are what matter most. At least that’s what matters most to other human beings.

DNA AND THE RANDOMNESS OF GENETIC PROBLEMS

Last Thanksgiving, I wrote about my profound gratitude for the natural, everyday, biological miracle of my newborn granddaughter. Georgiana just celebrated her first birthday, and this year I have new, and rather different, miracles to be thankful for.

The miraculously intricate process that transforms a few strands of DNA into a living creature is the product of blind biological forces. It can go wrong.

Georgie is a bright, pretty, exceptionally sweet baby. But a small random mutation in one of her genes means that she has a rare condition called Congenital Melanocytic Nevus, or CMN.

The most notable symptom of CMN is a giant mole, or “nevus,” along with many smaller moles. Georgie’s nevus covers much of her back. But CMN can also affect a child’s brain. And though everything about CMN is uncertain, it leads to something like a 2% to 5% risk for potentially fatal skin cancers. (The thought of a baby with melanoma should be confirmation enough that the universe is indifferent to human concerns.)

We are lucky so far. Georgie’s brain is just fine, and the nevus is in a relatively inconspicuous place. But somehow it doesn’t seem right to say that we are thankful for one set of blind chances when other babies are condemned by another set.

But here’s a miracle I am thankful for. Those blind, arbitrary, natural processes have created human beings who are not blind or arbitrary. Those human beings really do have reasons and designs, and, by their very nature, they can defy nature itself—including a condition like CMN.

Humans created science—we have the ability to understand the natural world and so to transform it. It is hard to get funding for research on rare diseases like CMN. But several scientists across the globe are still trying to figure out what’s wrong and how to fix it.

For example, in London, Veronica Kinsler at Great Ormond Street Hospital has taken advantage of the amazing scientific advances in genomics to pinpoint precisely which mutations cause CMN. Now that scientists know just which gene changes cause CMN, they have started to design ways to fix the damage. And those discoveries might help us to understand and treat skin cancer, too.

Human beings can not only transform nature, we can transform ourselves. Even a few years ago, someone with CMN could feel isolated and stigmatized. Thanks to the Internet, children with CMN, and the people who love them, have been able to find each other and form support groups: Nevus Outreach in the U.S. and Caring Matters Now in the U.K. Together, they have been able to raise money for research.

The support groups have done something else, too. It may be human nature to feel disturbed, at first, at the sight of a baby with a giant mole. But human beings can change the way that they think and feel, and there’s been a quiet social revolution in our feelings about disability and difference. Rick Guidotti, a successful fashion photographer, has taken on the mission of photographing individuals with genetic differences at Positiveexposure.org, including lovely photographs of people with CMN.

Of course, all grandmothers think that their grandchildren are uniquely beautiful, no matter what. So do Georgie’s parents and grandfathers and uncles and aunts and all the people who care for her. What could be more precious than Georgie’s wispy blond hair, the cleft in her chin, her charming laugh, her thoughtful look?

This might seem like an evolutionary illusion, just a way for our genes to get us to spread them. But I think instead that these perceptions of love point to a more profound truth. Ultimately, each of the six billion of us on the planet, each with our unique genetic makeup and irreducibly individual history, really is just that irreplaceable and valuable—and vulnerable, too.

This Thanksgiving I’m full of the deepest gratitude to the scientists and the support groups—but I’m most grateful of all to little Georgiana, who reminds me of that profound truth every day.

WHO WINS WHEN SMART CROWS AND KIDS MATCH WITS?

I am writing this looking out my window at the peaks and lakes of Middle-Earth, also known as New Zealand’s South Island. In the “Hobbit” movies, this sublime landscape played the role of the Misty Mountains.

But, of course, there aren’t really any supernaturally intelligent creatures around here—no noble Gwaihirs or sinister Crebain (my fellow Tolkien geeks will understand). Or are there?

In fact, I’m in New Zealand because of just such a creature, the New Caledonian crow. It lives on one obscure island 1,500 miles north of here. Gavin Hunt, Russell Gray and Alex Taylor at the University of Auckland (among others) have been studying these truly remarkable birds since Dr. Hunt discovered them 20 years ago.

New Caledonian crows make more sophisticated tools than any other animal except us. In the wild, they fashion sticks into hooked tools that they use to dig out delicious grubs from holes in trees. They turn palm leaves into digging tools, too. The process involves several steps, like stripping away leaves to create barbs for hooking grubs and nibbling the end of the stem to a sharp point.

Of course, many animals instinctively perform complex actions. But the crows are so impressive because they can actually learn how to create tools. In the lab, they can bend wires to make hooks, and they can use one new tool to get another. Like many very smart animals, including us, crow babies are immature for an exceptionally long time and they use their protected early life to learn their toolmaking skills.

Are New Caledonian crows as smart as a human child? It’s tempting to think about intelligence as an ineffable magical substance, like lembas or mithril in Tolkien’s novels, and to assume that we can measure just how much of it an individual person or an individual species possesses.

But that makes no sense from an evolutionary point of view. Every species is adapted to solve the particular problems of its own environment. So researchers have been trying to see how the crows’ adaptations compare to ours.

In a paper this year in the Proceedings of the Royal Society, I joined forces with Drs. Taylor and Gray and other colleagues, especially Anna Waismeyer at the University of Washington, to find out.

We gave the crows and 2-year-old children a problem to solve. For the crows, we balanced a sort of domino with meat on top in a hole in a machine. When they went to eat the meat, they accidentally tipped the domino over into the machine. Unexpectedly, that made the machine dispense even more meat from a separate opening. (We used marbles instead of meat for the children.)

Here was the question: Would the crows or the children be able to use this accidental event to design a new action? Could they imagine how to procure the treat on purpose, even though they had never done it before? If they just saw the block sitting on the table, would they pick it up and put it in the machine?

Despite their tool-using brilliance, the crows never got it—even after a hundred trials. They could learn to pick up the block and put it into the box through conditioning—that is, if they were rewarded for each step of the process—but not spontaneously. In contrast, most of the 2-year-olds learned from the accident. They could imagine how to get the marble, and could immediately pick up the block and put it in the box.

The crows have a deep understanding of how physical objects work, and they are very clever at using that knowledge to accomplish their goals. But the children seem to be better at noticing the novel, the accidental and the serendipitous and at using that experience to imagine new opportunities. It may be that same ability which lets us humans fashion ancient mountains and lakes into magical new worlds.

A MORE SUPPORTIVE WORLD CAN WORK WONDERS FOR THE AGED

This was a week of worry for my family. We were worrying about my 93-year-old mother-in-law—a lovely, bright, kind woman in the cruel grip of arthritis, Alzheimer’s and just plain old age. Of course, this is a commonplace, even banal story for my baby boomer generation, though no less painful for that. And it’s got an extra edge because we aren’t just worried about what will happen to our parents; we’re worried about what will happen to us, not just my husband and me, but our entire aging nation.

Getting old, with its unavoidable biological changes and its inevitable end, might simply seem like an inescapably tragic part of the human condition. (Whenever my grandmother began to complain about getting old, she would add wryly, “But consider the alternative . . .”)

But it’s hard to avoid feeling that there is something deeply and particularly wrong about the way we treat old age in American culture right now. Instead of seeing honor and dignity, sagacity and wisdom in the old, we see only pathology and pathos.

Could these cultural attitudes actually make the biological facts of aging worse?

A striking new study in the journal Psychological Science by Becca Levy at the Yale School of Public Health and colleagues suggests that cultural attitudes and physical well-being are far more closely intertwined than we might have thought. Exposing people to positive messages about aging, even through completely unconscious messages, actually makes them function better physically. In fact, the unconscious positive messages are more effective than conscious positive thinking.

The researchers looked at 100 older people aged 60 to 99. Every week for four weeks, they asked the participants to detect flashing lights on a screen and to write an essay. Words appeared on the flashing screen for a split second—so briefly that the participants didn’t know they were there. One group saw positive words about aging, such as “spry” and “wise,” then wrote an essay on a topic that had nothing to do with aging. Another group saw random letter combinations and then wrote an essay that described a thriving senior. A third group got both of the positive experiences, and a fourth got both neutral experiences.

Three weeks later, the researchers measured the elderly participants’ image of older people, in general, and their own self-image. They also gave them a standard medical test. It measured how well the seniors functioned physically—things like how easy it was to get up and down from a chair and how long it took to walk a few feet.

The people who had seen the positive messages—three weeks earlier, for only a split second, without knowing it—felt better about aging than those who hadn’t. Even more surprisingly, they also did much better on the physical tests. In fact, the subliminal messages gave them as great an advantage as seniors in another study who exercised for six months.

Consciously writing a positive essay didn’t have the same effect. This may be because consciously trying to think positively could be undermined by equally conscious skepticism (thriving seniors—yeah, right).

So in the lab, unconscious positive messages about aging can help. But in real life, of course, we’re surrounded by unconscious negative messages about aging, and they’re much more difficult to combat than explicit prejudice.

I’m personally optimistic anyway. At age 59, I’m on the tail end of the baby boom, and I’m relying on the older members of my generation to blaze the trail for me once more. After all, they persuaded our parents it was OK for us to have sex when we were 20, and then even persuaded our children that it was OK for us to have sex when we were 50.

Even the boomers can’t stop the inevitable march to the grave. But perhaps we can walk a little taller on the way there.

CAMPFIRES HELPED INSPIRE COMMUNITY CULTURE

It’s October, the nights are growing longer and my idea of heaven is an evening with a child or two, a stack of storybooks, a pot of cocoa and a good, blazing fire.

But what makes a fireside so entrancing? Why do we still long for roaring fireplaces, candlelit dinners, campfire tales? After all, we have simple, efficient electric lights and gas stoves. Fires are smoky, messy and unhealthy, hard to start and just as hard to keep going. (The three things every man is convinced he can do exceptionally well are drive a car, make love to a woman and start a fire—each with about the same degree of self-awareness.)

A new paper by Polly Wiessner of the University of Utah suggests that our longing for the fireside is a deep part of our evolutionary inheritance. Dr. Wiessner is an anthropologist who lived with the Ju/’hoansi people in Botswana and what is now Namibia in the 1970s, when they still lived by hunting and gathering, much like our ancestors. She recorded their talk.

Now, in what must be the most poetic article to ever appear in the Proceedings of the National Academy of Sciences, she has analyzed all the Ju/’hoansi conversations that involved at least five people. She compared how they talked by day to how they talked by night, over the fire.

The daytime talk was remarkably like the conversation in any modern office. The Ju/’hoansi talked about the work they had to do, gossiped and made rude jokes. Of the conversations, 34% were what Dr. Wiessner scientifically coded as CCC—criticism, complaint and conflict—the familiar grumbling and grousing, occasionally erupting into outright hatred, that is apparently the eternal currency of workplace politics.

But when the sun went down and the men and the women, the old and the young, gathered around the fire, the talk was transformed. People told stories 81% of the time—stories about people they knew, about past generations, about relatives in distant villages, about goings-on in the spirit world and even about those bizarre beings called anthropologists.

Some old men and women, in particular, no longer so productive by day, became master storytellers by night. Their enthralled listeners laughed and wept, sang and danced along, until they drifted off to sleep. Often, at around 2 a.m., some people would wake up again, stir the embers and talk some more.

This nighttime talk engaged some of our most distinctively human abilities—imagination, culture, spirituality. Over the fire, the Ju/’hoansi talked about people and places that were far away in space and time and possibility, they transmitted cultural wisdom and historical knowledge to the next generation, and they explored the mysterious psychological nuances of other minds.

The human ability to control fire had transformative biological effects. It allowed us to extract nourishment from the toughest roots and roasts, and to feed our hungry, helpless children, with their big energy-guzzling brains. But Dr. Wiessner suggests that it had equally transformative social effects. Fire gave us the evening —too dark to work, but bright and warm enough to talk.

In other studies, Dr. Whitney has shown that people can swiftly calculate how happy or sad a crowd is in much the same way.

Have screens destroyed the evening? The midnight memos and after-dinner emails do seem to turn the night into just more of the working day—a poor substitute for the fireside. On the other hand, perhaps I channel some of the Ju/’hoansi evening spirit when I gather with my grandchildren in the dark, in front of the gently flickering flat screen, and download Judy Garland and Bert Lahr masterfully telling the story of the wizards and witches of Oz. (Judy’s singing, in any case, however digital, is undoubtedly a substantial modern advance over grandmom’s.)

Still, a few candles, a flame or two, and some s’mores over the embers might help bring human light and warmth even to our chilling contemporary forms of darkness.

HUMANS NATURALLY FOLLOW CROWD BEHAVIOR

It happened last Sunday at football stadiums around the country. Suddenly, 50,000 individuals became a single unit, almost a single mind, focused intently on what was happening on the field—that particular touchdown grab or dive into the end zone. Somehow, virtually simultaneously, each of those 50,000 people tuned into what the other 49,999 were looking at.

Becoming part of a crowd can be exhilarating or terrifying: The same mechanisms that make people fans can just as easily make them fanatics. And throughout human history we have constructed institutions that provide that dangerous, enthralling thrill. The Coliseum that hosts my local Oakland Raiders is, after all, just a modern knockoff of the massive theater that housed Roman crowds cheering their favorite gladiators 2,000 years ago.

(For Oakland fans, like my family, it's particularly clear that participating in the Raider Nation is responsible for much of the games' appeal—it certainly isn't the generally pathetic football.)

In fact, recent studies suggest that our sensitivity to crowds is built into our perceptual system and operates in a remarkably swift and automatic way. In a 2012 paper in the Proceedings of the National Academy of Sciences, A.C. Gallup, then at Princeton University, and colleagues looked at the crowds that gather in shopping centers and train stations.

In one study, a few ringers simply joined the crowd and stared up at a spot in the sky for 60 seconds. Then the researchers recorded and analyzed the movements of the people around them. The scientists found that within seconds hundreds of people coordinated their attention in a highly systematic way. People consistently stopped to look toward exactly the same spot as the ringers.

The number of ringers ranged from one to 15. People turn out to be very sensitive to how many other people are looking at something, as well as to where they look. Individuals were much more likely to follow the gaze of several people than just a few, so there was a cascade of looking as more people joined in.

In a new study in Psychological Science, Timothy Sweeny at the University of Denver and David Whitney at the University of California, Berkeley, looked at the mechanisms that let us follow a crowd in this way. They showed people a set of four faces, each looking in a slightly different direction. Then the researchers asked people to indicate where the whole group was looking (the observers had to swivel the eyes on a face on a computer screen to match the direction of the group).

Because we combine head and eye direction in calculating a gaze, the participants couldn't tell where each face was looking by tracking either the eyes or the head alone; they had to combine the two. The subjects saw the faces for less than a quarter of a second. That's much too short a time to look at each face individually, one by one.

It sounds impossibly hard. If you try the experiment, you can barely be sure of what you saw at all. But in fact, people were amazingly accurate. Somehow, in that split-second, they put all the faces together and worked out the average direction where the whole group was looking.

In other studies, Dr. Whitney has shown that people can swiftly calculate how happy or sad a crowd is in much the same way.

Other social animals have dedicated brain mechanisms for coordinating their action—that's what's behind the graceful rhythms of a flock of birds or a school of fish. It may be hard to think of the eccentric, gothic pirates of Oakland's Raider Nation in the same way. A fan I know says that going to a game is like being plunged into an unusually friendly and cooperative postapocalyptic dystopia—a marijuana-mellowed Mad Max.

But our brains seem built to forge a flock out of even such unlikely materials.

IN LIFE, WHO WINS, THE FOX OR THE HEDGEHOG?

A philosopher once used an animal metaphor – the clever fox - to point out the most important feature of certain especially distinctive thinkers.

It was not, however, Isiah Berlin. Berlin did famously divide thinkers into the two categories, hedgehogs and foxes. He based the distinction on a saying by the ancient Greek philosopher Archilochus “The fox knows many things but the hedgehog knows one big thing”. Hedgehogs have a single grand idea they apply to everything, foxes come up with a new idea for every situation. Berlin said that Plato and Dostoevsky were hedgehogs, Aristotle and Shakespeare were foxes.

Berlin later regretted inventing this over-simplified dichotomy. But it's proved irresistible to writers ever after. After all, as Robert Benchley, said there are just two kinds of people in the world, those who think there are just two kinds of people in the world and those who don’t.

Philosophical and political hedgehogs got most of the glamour and attention in the twentieth century. But lately there has been a turn towards foxes. The psychologist Phillip Tetlock studied expert political predictions and found that foxy, flexible, pluralistic experts were much more accurate than the experts with one big hedgehog idea. The statistics wiz Nate Silver chose a fox as his logo in tribute to this finding.

But here is a question that Berlin, that archetypal Oxford don, never considered. What about the babies? What makes young hedgehogs and foxes turn out the way they do?

Biologists confirm that Archilocus, got it right, foxes are far more wily and flexible learners than hedgehogs. But hedgehogs also have a much shorter childhood than foxes. Hedgehogs develop their spines, that one big thing, almost as soon as they are born, and are independent in only six weeks. Fox cubs still return to the den for six months. As a result hedgehogs need much less parental care - hedgehog fathers disappear after they mate. Fox couples, in contrast, “pair-bond” - the fathers help bring food to the babies.

Baby foxes also play much more than hedgehogs, though in a slightly creepy way. Fox parents start out by feeding the babies their own regurgitated food. But then they actually bring the babies live prey, like mice, when they are still in the den, and the babies play at hunting them. That play gives them a chance to practice and develop the flexible hunting skills and wily intelligence that serve them so well later on.

In fact, the much earlier, anonymous, philosopher seems to have understood the behavioral ecology of foxes, and the link between intelligence, play and parental investment, rather better than Berlin did. The splendid song The Fox, beloved by every four-year-old, was first recorded on the blank flyleaf of a 15th century copy of “Sayings of the Philosophers”. The Chaucerian philosopher not only described the clever, sociable carnivore who outwits even the homo sapiens. But he (or perhaps she?) also noted that the fox is the kind of creature who brings back the prey to the little ones in his cozy den. That grey goose was a source of cognitive practice and skill formation as well as tasty bones-o.

Berlin doesn’t have much to say about whether Plato the hedgehog and Aristotle the fox had devoted or deadbeat Dads, or if they had much playtime as philosopher pups. Though, of course, the young cubs game of hunting down terrified live prey while their elders look on approvingly will seem familiar to those who have attended philosophy graduate seminars.

WHY IS IT SO HARD FOR US TO DO NOTHING?

It is summer time, and the living is easy. You can, at last, indulge in what is surely the most enjoyable of human activities—doing absolutely nothing. But is doing nothing really enjoyable? A new study in the journal Science shows that many people would rather get an electric shock than just sit and think.

Neuroscientists have inadvertently discovered a lot about doing nothing. In brain-imaging studies, people lie in a confined metal tube feeling bored as they wait for the actual experiment to start. Fortuitously, neuroscientists discovered that this tedium was associated with a distinctive pattern of brain activity. It turns out that when we do nothing, many parts of the brain that underpin complex kinds of thinking light up.

Though we take this kind of daydreaming for granted, it is actually a particularly powerful kind of thinking. Much more than any other animal, we humans have evolved the ability to live in our own thoughts, detached from the demands of our immediate actions and experiences. When people lie in a tube with nothing else to do, they reminisce, reliving events in the past ("Damn it, that guy was rude to me last week"), or they plan what they will do in the future ("I'll snub him next time"). And they fantasize: "Just imagine how crushed he would have been if I'd made that witty riposte."

Descartes had his most important insights sitting alone in a closet-sized stove, the only warm spot during a wintry Dutch military campaign. When someone asked Newton how he discovered the law of gravity, he replied, "By thinking on it continually." Doing nothing but thinking can be profound.

But is it fun? Psychologist Tim Wilson of the University of Virginia and his colleagues asked college students to sit for 15 minutes in a plain room doing nothing but thinking. The researchers also asked them to record how well they concentrated and how much they enjoyed doing it. Most of the students reported that they couldn't concentrate; half of them actively disliked the experience.

Maybe that was because of what they thought about. "Rumination"—brooding on unpleasant experiences, like the guy who snubbed you—can lead to depression, even clinical depression. But the researchers found no difference based on whether people recorded positive or negative thoughts.

Maybe it was something about the sterile lab room. But the researchers also got students just to sit and think in their own homes, and they disliked it even more. In fact, 32% of the students reported that they cheated, with a sneak peek at a cellphone or just one quick text.

But that's because they were young whippersnappers with Twitter-rotted brains, right? Wrong. The researchers also did the experiment with a middle-aged church group, and the results were the same. Age, gender, personality, social-media use—nothing made much difference.

But did people really hate thinking that much? The researchers gave students a mild electric shock and asked if they would pay to avoid another. The students sensibly said that they would. The researchers then put them back in the room with nothing to do but also gave them the shock button.

Amazingly, many of them voluntarily shocked themselves rather than doing nothing. Not so amazingly (at least to this mother of boys who played hockey), there was a big sex difference. Sixty-seven percent of the men preferred a shock to doing nothing, but only 25% of the women did.

Newton and neuroscience suggest that just thinking can be very valuable. Why is it so hard? It is easy to blame the modern world, but 1,000 years ago, Buddhist monks had the same problem. Meditation has proved benefits, but it takes discipline, practice and effort. Our animal impulse to be up and doing, or at least up and checking email, is hard to resist, even in a long, hazy cricket-song dream of a summer day.

FOR POOR KIDS, NEW PROOF THAT EARLY HELP IS KEY

Twenty years ago, I would have said that social policies meant to help very young children are intrinsically valuable. If improving the lives of helpless, innocent babies isn't a moral good all by itself, what is? But I also would have said, as a scientist, that it would be really hard, perhaps impossible, to demonstrate the long-term economic benefits of those policies. Human development is a complicated, interactive and unpredictable business.

Individual children are all different. Early childhood experience is especially important, but it's not, by any means, the end of the story. Positive early experiences don't inoculate you against later deprivation; negative ones don't doom you to inevitable ruin. And determining the long-term effects of any social policy is notoriously difficult. Controlled experiments are hard, different programs may have different effects, and unintended consequences abound.

I still think I was right on the first point: The moral case for early childhood programs shouldn't depend on what happens later. But I was totally, resoundingly, dramatically wrong about whether one could demonstrate long-term effects. In fact, over the last 20 years, an increasing number of studies—many from hardheaded economists at business schools—have shown that programs that make life better for young children also have long-term economic benefits.

The most recent such study was published in the May 30 issue of Science. Paul Gertler, of the National Bureau of Economic Research and the Haas School of Business of the University of California, Berkeley, and colleagues looked at babies growing up in Jamaica. (Most earlier studies had just looked at children in the U.S.) These children were so poor that they were "nutritionally stunted"—that is, they had physical symptoms of malnourishment.

Health aides visited one group of babies every week for two years, starting at age 1. The aides themselves played with the babies and helped encourage the parents to play with them in stimulating ways. Another randomly determined group just got weekly nutritional supplements, a third received psychological and nutritional help, and a fourth group was left alone.

Twenty years later, when the children had grown up, the researchers returned and looked at their incomes. The young adults who had gotten the early psychological help had significantly higher incomes than those who hadn't. In fact, they earned 25% more than the control group, even including the children who had just gotten better food.

This study and others like it have had some unexpected findings. The children who were worst off to begin with reaped the greatest benefits. And the early interventions didn't just influence grades. The children who had the early help ended up spending more time in school, and doing better there, than the children who didn't. But the research has found equally important effects on earnings, physical health and even crime. And interventions that focus on improving early social interactions may be as important and effective as interventions focused on academic skills.

The program influenced the parents too, though in subtle ways. The researchers didn't find any obvious differences in the ways that parents treated their children when they were 7 and 11 years old. It might have looked as if the effects of the intervention had faded away.

Nevertheless, the parents of children who had had the psychological help were significantly more likely to immigrate to another country later on. Those health visits stopped when the children were only 4. But both the parents and the children seemed to gain a new sense of opportunity that could change their whole lives.

I'm really glad I was so wrong. In the U.S., 20% of children still grow up in poverty. The self-evident moral arguments for helping those children have fueled the movement toward early childhood programs in red Oklahoma and Georgia as well as blue New York and Massachusetts. But the scientific and economic arguments have become just as compelling.

THE WIDE REACH OF BABIES' WEBS OF ADORABLENESS

We've all seen the diorama in the natural history museum: the mighty cave men working together to bring down the mastodon. For a long time, evolutionary biologists pointed to guy stuff like hunting and warfare to explain the evolution of human cooperation.

But a recent research symposium at the University of California, San Diego, suggests that the children watching inconspicuously at the back of the picture may have been just as important. Caring for children may, literally, have made us human—and allowed us to develop our distinctive abilities for cognition, cooperation and culture. The same sort of thinking suggests that human mothering goes way beyond mothers. (You can see a video here.).

The anthropologist Sarah Hrdy argued that human evolution depends on the emergence of "cooperative breeding." Chimpanzee babies are exclusively cared for by their biological mothers; they'll fight off anyone else who comes near their babies. We humans, in contrast, have developed a caregiving triple threat: Grandmothers, fathers and "alloparents" help take care of babies. That makes us quite different from our closest primate relatives.

In my last column, I talked about the fascinating new research on grandmothers. The fact that fathers take care of kids may seem more obvious, but it also makes us distinctive. Humans "pair bond" in a way that most primates—indeed, most mammals—don't. Fathers and mothers develop close relationships, and we are substantially more monogamous than any of our close primate relatives. As in most monogamous species, even sorta-kinda-monogamous ones like us, human fathers help to take care of babies.

Father care varies more than mother care. Even in hunter-gatherer or forager societies, some biological fathers are deeply involved in parenting, while others do very little. For fathers, even more than for mothers, the very fact of intimacy with babies is what calls out the impulse to care for them. For example, when fathers touch and play with babies, they produce as much oxytocin (the "tend and befriend" hormone) as mothers do.

Humans also have "alloparents"—other adults who take care of babies even when they aren't related to them. In forager societies, those alloparents are often young women who haven't yet had babies themselves. Caring for other babies lets these women learn child-care skills while helping the babies to survive. Sometimes mothers swap caregiving, helping each other out. If you show pictures of especially cute babies to women who don't have children, the reward centers of their brains light up (though we really didn't need the imaging studies to conclude that cute babies are irresistible to just about everybody).

Dr. Hrdy thinks that this cooperative breeding strategy is what let us develop other distinctive human abilities. A lot of our human smartness is social intelligence; we're especially adept at learning about and from other people. Even tiny babies who can't sit up yet can smile and make eye contact, and studies show that they can figure out what other people want.

Dr. Hrdy suggests that cooperative breeding came first and that the extra investment of grandmothers, fathers and alloparents permitted the long human childhood that in turn allowed learning and culture. In fact, social intelligence may have been a direct result of the demands of cooperative breeding. As anybody who has carpooled can testify, organizing joint child care is just as cognitively challenging as bringing down a mastodon.

What's more, Dr. Hrdy suggests that in a world of cooperative breeding, babies became the agents of their own survival. The weapons-grade cuteness of human babies goes beyond their big eyes and fat cheeks. Babies first use their social intelligence to actively draw dads and grandmoms and alloparents into their web of adorableness. Then they can use it to do all sorts of other things—even take down a mastodon or two.

SEE JANE EVOLVE: PICTURE BOOKS EXPLAIN DARWIN

Evolution by natural selection is one of the best ideas in all of science. It predicts and explains an incredibly wide range of biological facts. But only 60% of Americans believe evolution is true. This may partly be due to religious ideology, of course, but studies show that many secular people who say they believe in evolution still don't really understand it. Why is natural selection so hard to understand and accept? What can we do to make it easier?

A new study in Psychological Science by Deborah Kelemen of Boston University and colleagues helps to explain why evolution is hard to grasp. It also suggests that we should teach children the theory of natural selection while they are still in kindergarten instead of waiting, as we do now, until they are teenagers.

Scientific ideas always challenge our common sense. But some ideas, such as the heliocentric solar system, require only small tweaks to our everyday knowledge. We can easily understand what it would mean for the Earth to go around the sun, even though it looks as if the sun is going around the Earth. Other ideas, such as relativity or quantum mechanics, are so wildly counterintuitive that we shrug our shoulders, accept that only the mathematicians will really get it and fall back on vague metaphors.

But evolution by natural selection occupies a not-so-sweet spot between the intuitive and the counterintuitive. The trouble is that it's almost, but not really, like intentional design, and that's confusing. Adaptation through natural selection, like intentional design, makes things work better. But the mechanism that leads to that result is very different.

Intentional design is an excellent everyday theory of human artifacts. If you wanted to explain most of the complicated objects in my living room, you would say that somebody intentionally designed them to provide light or warmth or a place to put your drink—and you'd be right. Even babies understand that human actions are "teleological"—designed to accomplish particular goals. In earlier work, Dr. Kelemen showed that preschoolers begin to apply this kind of design thinking more generally, an attitude she calls "promiscuous teleology."

By elementary-school age, children start to invoke an ultimate God-like designer to explain the complexity of the world around them—even children brought up as atheists. Kids aged 6 to 10 have developed their own coherent "folk biological" theories. They explain biological facts in terms of intention and design, such as the idea that giraffes develop long necks because they are trying to reach the high leaves.

Dr. Kelemen and her colleagues thought that they might be able to get young children to understand the mechanism of natural selection before the alternative intentional-design theory had become too entrenched. They gave 5- to 8-year-olds 10-page picture books that illustrated an example of natural selection. The "pilosas," for example, are fictional mammals who eat insects. Some of them had thick trunks, and some had thin ones. A sudden change in the climate drove the insects into narrow underground tunnels. The thin-trunked pilosas could still eat the insects, but the ones with thick trunks died. So the next generation all had thin trunks.

Before the children heard the story, the experimenters asked them to explain why a different group of fictional animals had a particular trait. Most of the children gave explanations based on intentional design. But after the children heard the story, they answered similar questions very differently: They had genuinely begun to understand evolution by natural selection. That understanding persisted when the experimenters went back three months later.

One picture book, of course, won't solve all the problems of science education. But these results do suggest that simple story books like these could be powerful intellectual tools. The secret may be to reach children with the right theory before the wrong one is too firmly in place.

THE KID WHO WOULDN'T LET GO OF 'THE DEVICE'

How does technology reshape our children’s minds and brains? Here is a disturbing story from the near future.

They gave her The Device when she was only two. It worked through a powerful and sophisticated optic nerve brain-mind interface, injecting it’s content into her cortex. By the time she was five, she would immediately be swept away into the alternate universe that the device created. Throughout her childhood, she would become entirely oblivious to her surroundings in its grip, for hours at a time. She would surreptitiously hide it under her desk at school, and reach for it immediately as soon as she got home. By adolescence, the images of the device – a girl entering a ballroom, a man dying on a battlefield – were more vivid to her than her own memories.

As a grown woman her addiction to The Device continued. It dominated every room of her house, even the bathroom. Its images filled her head even when she made love. When she travelled, her first thought was to be sure that she had access to The Device and she was filled with panic at the thought that she would have to spend a day without it. When her child broke his arm, she paused to make sure that The Device would be with her in the emergency room. Even sadder, as soon as her children were old enough she did her very best to connect them to The Device, too.

The psychologists and neuroscientists showed just how powerful The Device had become. Psychological studies showed that its users literally could not avoid entering its world, the second they made contact their brains automatically and involuntarily engaged with it. More, large portions of their brains that had originally been designed for other purposes had been hijacked to the exclusive service of The Device.

Well, anyway, I hope that this is a story of the near future. It certainly is a story of the near past. The Device, you see, is the printed book, and the story is my autobiography.

Socrates was the first to raise the alarm about this powerful new technology – he argued, presciently, that the rise of reading would destroy the old arts of memory and discussion.

The latest Device to interface with my retina is “Its Complicated: The Social Networked Life of Teens” by Danah Boyd at NYU and Microsoft Research. Digital social network technologies play as large a role in the lives of current children as books once did for me. Boyd spent thousands of hours with teenagers from many different backgrounds, observing the way they use technology and talking to them about what technology meant to them.

Her conclusion is that young people use social media to do what they have always done – establish a community of friends and peers, distance themselves from their parents, flirt and gossip, bully, experiment, rebel. At the same time, she argues that the technology does make a difference, just as the book, the printing press and the telegraph did. An ugly taunt that once dissolved in the fetid locker-room air can travel across the world in a moment, and linger forever. Teenagers must learn to reckon with and navigate those new aspects of our current technologies, and for the most part that’s just what they do.

Boyd thoughtfully makes the case against both the alarmists and the techtopians. The kids are all right or at least as all right as kids have ever been.

So why all the worry? Perhaps it’s because of the inevitable difference between looking forward towards generational changes or looking back at them. As the parable of The Device illustrates we always look at our children’s future with equal parts unjustified alarm and unjustified hope – utopia and dystopia. We look at our own past with wistful nostalgia. It may be hard to believe but Boyd’s book suggests that someday even Facebook will be a fond memory.

ARE SCHOOLS ASKING TO DRUG KIDS FOR BETTER TEST SCORES?

In the past two decades, the number of children diagnosed with Attention Deficit Hyperactivity Disorder has nearly doubled. One in five American boys receives a diagnosis by age 17. More than 70% of those who are diagnosed—millions of children—are prescribed drugs.

A new book, "The ADHD Explosion" by Stephen Hinshaw and Richard Scheffler, looks at this extraordinary increase. What's the explanation? Some rise in environmental toxins? Worse parenting? Better detection?

Many people have suspected that there is a relationship between the explosion in ADHD diagnoses and the push by many states, over this same period, to evaluate schools and teachers based on test scores. But how could you tell? It could just be a coincidence that ADHD diagnoses and high-stakes testing have both increased so dramatically. Drs. Hinshaw and Scheffler—both of them at the University of California, Berkeley, my university—present some striking evidence that the answer lies, at least partly, in changes in educational policy.

Drs. Hinshaw and Scheffler used a kind of "natural experiment." Different parts of the country introduced new educational policies at different times. The researchers looked at the relationship between when a state introduced the policies and the rate of ADHD diagnoses. They found that right after the policies were introduced, the diagnoses increased dramatically. Moreover, the rise was particularly sharp for poor children in public schools.

The authors suggest that when schools are under pressure to produce high test scores, they become motivated, consciously or unconsciously, to encourage ADHD diagnoses—either because the drugs allow low-performing children to score better or because ADHD diagnoses can be used to exclude children from testing. They didn't see comparable increases in places where the law kept school personnel from recommending ADHD medication to parents.

These results have implications for the whole way we think about ADHD. We think we know the difference between a disease and a social problem. A disease happens when a body breaks or is invaded by viruses or bacteria. You give patients the right treatment, and they are cured. A social problem—poverty, illiteracy, crime—happens when institutions fail, when instead of helping people to thrive they make them miserable.

Much debate over ADHD has focused on whether it is a disease or a problem, "biological" or "social." But the research suggests that these are the wrong categories. Instead, it seems there is a biological continuum among children. Some have no trouble achieving even "unnatural" levels of highly focused attention, others find it nearly impossible to focus attention at all, and most are somewhere in between.

That variation didn't matter much when we were hunters or farmers. But in our society, it matters terrifically. School is more essential for success, and a particular kind of highly focused attention is more essential for school.

Stimulant drugs don't "cure" a disease called ADHD, the way that antibiotics cure pneumonia. Instead, they seem to shift attentional abilities along that continuum. They make everybody focus better, though sometimes with serious costs. For children at the far end of the continuum, the drugs may help make the difference between success and failure, or even life and death. But the drugs also lead to more focused attention, even in the elite college students who pop Adderall before an exam, risking substance abuse in the mad pursuit of even better grades.

For some children the benefits of the drugs may outweigh the drawbacks, but for many more the drugs don't help and may harm. ADHD is both biological and social, and altering medical and educational institutions could help children thrive. Behavioral therapies can be very effective, but our medical culture makes it much easier to prescribe a pill. Instead of drugging children's brains to get them to fit our schools, we could change our schools to accommodate a wider range of children's brains.

TIME TO RETIRE THE SIMPLICITY OF NATURE VS. NURTURE

Are we moral by nature or as a result of learning and culture? Are men and women “hard-wired” to think differently? Do our genes or our schools make us intelligent? These all seem like important questions, but maybe they have no good scientific answer.

Once, after all, it seemed equally important to ask whether light was a wave or a particle, or just what arcane force made living things different from rocks. Science didn’t answer these questions—it told us they were the wrong questions to ask. Light can be described either way; there is no single cause of life.

Every year on the Edge website the intellectual impresario and literary agent John Brockman asks a large group of thinkers to answer a single question. (Full disclosure: Brockman Inc. is my agency.) This year, the question is about which scientific ideas should be retired.

Surprisingly, many of the writers gave a similar answer: They think that the familiar distinction between nature and nurture has outlived its usefulness.

Scientists who focus on the “nature” side of the debate said that it no longer makes sense to study “culture” as an independent factor in human development. Scientists who focus on learning, including me, argued that “innateness” (often a synonym for nature) should go. But if you read these seemingly opposed answers more closely, you can see a remarkable degree of convergence.

Scientists have always believed that the human mind must be the result of some mix of genes and environment, innate structure and learning, evolution and culture. But it still seemed that these were different causal forces that combined to shape the human mind, and we could assess the contribution of each one separately. After all, you can’t have water without both hydrogen and oxygen, but it’s straightforward to say how the two elements are combined.

As many of the writers in the Edge symposium point out, however, recent scientific advances have made the very idea of these distinctions more dubious.

One is the explosion of work in the field of epigenetics. It turns out that there is a long and circuitous route, with many feedback loops, from a particular set of genes to a feature of the adult organism. Epigenetics explores the way that different environments shape this complex process, including whether a gene is expressed at all.

A famous epigenetic study looked at two different strains of mice. The mice in each strain were genetically identical to each other. Normally, one strain is much smarter than the other. But then the experimenters had the mothers of the smart strain raise the babies of the dumb strain. The babies not only got much smarter, they passed this advantage on to the next generation.

So were the mice’s abilities innate or learned? The result of nature or nurture? Genes or environment? The question just doesn’t make sense.

New theories of human evolution and culture have also undermined these distinctions. The old evolutionary psychology suggested that we had evolved with very specific “modules”—finely calibrated to a particular Stone Age environment.

But new research has led biologists to a different view. We didn’t adapt to a particular Stone Age environment. We adapted to a newly unpredictable and variable world. And we did it by developing new abilities for cultural transmission and change. Each generation could learn new skills for coping with new environments and could pass those skills on to the next generation.

As the anthropologist Pascal Boyer points out in his answer, it’s tempting to talk about “the culture” of a group as if this is some mysterious force outside the biological individual or independent of evolution. But culture is a biological phenomenon. It’s a set of abilities and practices that allow members of one generation to learn and change and to pass the results of that learning on to the next generation. Culture is our nature, and the ability to learn and change is our most important and fundamental instinct.

WHAT CHILDREN REALLY THINK ABOUT MAGIC

This Week we will counter the cold and dark with the warmth and light of fantasy, fiction and magic—from Santa to Scrooge, from Old Father Time and Baby New Year to the Three Kings of Epiphany. Children will listen to tales of dwarves and elves and magic rings in front of an old-fashioned fire or watch them on a new-fashioned screen.

But what do children really think about magic? The conventional wisdom is that young children can’t discriminate between the real and the imaginary, fact and fantasy. More recently, however, researchers like Jacqueline Woolley at the University of Texas and Paul Harris at Harvard have shown that even the youngest children understand magic in surprisingly sophisticated ways.

For instance, Dr. Woolley showed preschoolers a box of pencils and an empty box. She got them to vividly imagine that the empty box was full of pencils. The children enthusiastically pretended, but they also said that if someone wanted pencils, they should go to the real box rather than the imagined one.

Even young children make a sort of metaphysical distinction between two worlds. One is the current, real world with its observable events, incontrovertible facts and causal laws. The other is the world of pretense and possibility, fiction and fantasy.

Children understand the difference. They know that the beloved imaginary friend isn’t actually real and that the terrifying monster in the closet doesn’t actually exist (though that makes them no less beloved or scary). But children do spend more time than we do thinking about the world of imagination. They don’t actually confuse the fantasy world with the real one—they just prefer to hang out there.

Why do children spend so much time thinking about wild possibilities? We humans are remarkably good at imagining ways the world could be different and working out the consequences. Philosophers call it “counterfactual” thinking, and it’s one of our most valuable abilities.

Scientists work out what would happen if the physical world were different, and novelists work out what would happen if the social and psychological world were different. Scientific hypotheses and literary fictions both consider the consequences of small tweaks to our models of the world; mythologies consider much larger changes. But the fundamental psychology is the same. Young children seem to practice this powerful way of thinking in their everyday pretend play.

For scientists and novelists and 3-year-olds to be good at counterfactual reasoning, though, they must be able to preserve a bright line between imaginary possibilities and current reality.

But, particularly as they get older, children also begin to think that this bright line could be crossed. They recognize the possibility of “real” magic. It is conceivable to them, as it is to adults, that somehow the causal laws could be suspended, or creatures from the imaginary world could be transported to the real one. Dr. Harris did an experiment where children imagined a monster in the box instead of pencils. They still said that the monster wasn’t real, but when the experimenter left the room, they moved away from the box—just in case. Santa Claus is confusing because he is a fiction who at least seems to leave an observable trail of disappearing cookies and delivered presents.

The great conceptual advance of science was to reject this second kind of magic, the kind that bridges the real and the imagined, whether it is embodied in religious fundamentalism or New Age superstition. But at the same time, like the 3-year-olds, scientists and artists are united in their embrace of both reality and possibility, and their capacity to discriminate between them. There is no conflict between celebrating the magic of fiction, myth and metaphor and celebrating science. Counterfactual thinking is an essential part of science, and science requires and rewards imagination as much as literature or art.

Scientists, artists and 3-year-olds are united in their embrace of reality and possibility.

GRATITUTE FOR THE COSMIC MIRACLE OF A NEWBORN CHILD

Last week I witnessed three miracles. These miracles happen thousands of times a day but are no less miraculous for that. The first was the miracle of life. Amino acids combined to make just the right proteins, which sent out instructions to make just the right neurons, which made just the right connections to other neurons. And that brought a new, utterly unique, unprecedented consciousness—a new human soul—into the world.

Georgiana, my newborn granddaughter, already looks out at the world with wide-eyed amazement.

The second was the miracle of learning. This new consciousness can come to encompass the whole world. Georgiana is already tracking the movements of her toy giraffe. She’s learning to recognize her father’s voice and the scent of her mother’s breast. And she’s figuring out that the cries of “She’s so sweet!” are English rather than Japanese.

In just 20 years she may know about quarks and leptons, black holes and red dwarves, the beginning and end of the universe. Maybe by then she’ll know more than we do about how a newborn mind can learn so much, so quickly and so well. Her brain, to borrow from Emily Dickinson, is wider than the sky, deeper than the sea.

Georgie looks most intently at the admiring faces of the people who surround her. She is already focused on learning what we’re like. And that leads to the most important miracle of all: the miracle of love.

The coordination of amino acids and neurons that brought Georgiana to life is a stunning evolutionary achievement. But so is the coordination of human effort and ingenuity and devotion that keeps her alive and thriving.

Like all human babies, she is so heartbreakingly fragile, so helpless. And yet that very fragility almost instantly calls out a miraculous impulse to take care of her. Her mom and dad are utterly smitten, of course, not to mention her grandmom. But it goes far beyond just maternal hormones or shared genes.

The little hospital room is crowded with love—from two-year-old brother Augie to 70-year-old Grandpa, from Uncle Nick and Aunt Margo to the many in-laws and girlfriends and boyfriends. The friends who arrive with swaddling blankets, the neighbors who drop off a cake, the nurses and doctors, the baby sitters and child-care teachers—all are part of a network of care as powerful as the network of neurons.

That love and care will let Georgiana’s magnificent human brain, mind and consciousness grow and change, explore and create. The amino acids and proteins miraculously beat back chaos and create the order of life. But our ability to care for each other and our children—our capacity for culture—also creates miraculous new kinds of order: the poems and pictures of art, the theories and technologies of science.

It may seem that science depicts a cold, barren, indifferent universe—that Georgiana is just a scrap of carbon and water on a third-rate planet orbiting an unimpressive sun in an obscure galaxy. And it is true that, from a cosmic perspective, our whole species is as fragile, as evanescent, as helpless, as tiny as she is.

But science also tells us that the entirely natural miracles of life, learning and love are just as real as the cosmic chill. When we look at them scientifically, they turn out to be even more wonderful, more genuinely awesome, than we could have imagined. Like little Georgie, their fragility just makes them more precious.

Of course, on this memorable Thanksgiving my heart would be overflowing with gratitude for this one special, personal, miracle baby even if I’d never heard of amino acids, linguistic discrimination or non-kin investment. But I’ll also pause to give thanks for the general human miracle. And I’ll be thankful for the effort, ingenuity and devotion of the scientists who help us understand and celebrate it.

WORLD SERIES RECAP: MAY BASEBALL'S IRRATIONAL HEART KEEP ON BEATING

The last 15 years have been baseball's Age Of Enlightenment. The quants and nerds brought reason and science to the dark fortress of superstition and mythology that was Major League Baseball. The new movement was pioneered by the brilliant Bill James (adviser to this week's World Champion Red Sox), implemented by Billy Beane (the fabled general manager of my own Oakland Athletics) and immortalized in the book and movie "Moneyball."

Over this same period, psychologists have discovered many kinds of human irrationality. Just those biases and foibles that are exploited, in fact, by the moneyball approach. So if human reason has changed how we think about baseball, it might be baseball's turn to remind us of the limits of human reason.

We overestimate the causal power of human actions. So, in the old days, managers assumed that gutsy, active base stealers caused more runs than they actually do, and they discounted the more passive players who waited for walks. Statistical analysis, uninfluenced by the human bias toward action, led moneyballers to value base-stealing less and walking more.

We overgeneralize from small samples, inferring causal regularities where there is only noise. So we act as if the outcome of a best-of-7 playoff series genuinely indicates the relative strength of two teams that were practically evenly matched over a 162-game regular season. The moneyballer doesn't change his strategy in the playoffs, and he refuses to think that playoff defeats are as significant as regular season success.

We confuse moral and causal judgments. Jurors think a drunken driver who is in a fatal accident is more responsible for the crash than an equally drunken driver whose victim recovers. The same goes for fielders; we fans assign far more significance to a dramatically fumbled ball than to routine catches. The moneyball approach replaces the morally loaded statistic of "errors" with more meaningful numbers that include positive as well as negative outcomes.

By avoiding these mistakes, baseball quants have come much closer to understanding the true causal structure of baseball, and so their decisions are more effective.

But does the fact that even experts make so many mistakes about baseball prove that human beings are thoroughly irrational? Baseball, after all, is a human invention. It's a great game exactly because it's so hard to understand, and it produces such strange and compelling interactions between regularity and randomness, causality and chaos.

Most of the time in the natural environment, our evolved learning procedures get the right answers, just as most of the time our visual system lets us see the objects around us accurately. In fact, we really only notice our visual system on the rare occasions when it gives us the wrong answers, in perceptual illusions, for instance. A carnival funhouse delights us just because we can't make sense of it.

Baseball is a causal funhouse, a game designed precisely to confound our everyday causal reasoning. We can never tell just how much any event on the field is the result of skill, luck, intention or just grace. Baseball is a machine for generating stories, and stories are about the unexpected, the mysterious, even the miraculous.

Sheer random noise wouldn't keep us watching. But neither would the predictable, replicable causal regularities we rely on every day. Those are the regularities that evolution designed us to detect. But what can even the most rational mind do but wonder at the absurdist koan of the obstruction call, with its dizzying mix of rules, intentions and accidents, that ended World Series Game 3?

The truly remarkable thing about human reasoning isn't that we were designed by evolution to get the right answers about the world most of the time. It's that we enjoy trying to get the right answers so profoundly that we intentionally make it hard for ourselves. We humans, uniquely, invent art-forms serving no purpose except to stretch the very boundaries of rationality itself.

POVERTY CAN TRUMP A WINNING HAND OF GENES

We all notice that some people are smarter than others. You might naturally wonder how much those differences in intelligence are the result of genes or of upbringing. But that question, it turns out, is impossible to answer.

That’s because changes in our environment can actually transform the relation between our traits, our upbringing, and our genes.

The textbook illustration of this is a dreadful disease called PKU. Some babies have a genetic mutation which means that they can’t process an amino acid in their food. That leads to severe mental retardation. For centuries, PKU was incurable. Genetics determined whether someone suffered from the syndrome, and so had a low IQ.

But then scientists discovered how PKU worked. Now, we can immediately put babies with the mutation on a special diet. So, now, whether a baby with PKU has a low IQ is determined by the food they eat—their environment.

We humans can figure out how our environment works and act to change it, as we did with PKU. So if you’re trying to measure the influence of human nature and nurture you have to consider not just the current environment, but also all the possible environments that we can create.

This doesn’t just apply to obscure diseases. In the latest issue of Psychological Science Timothy C. Bates of the University of Edinburgh and colleagues report a study of the relationship between genes, SES (socio-economic status, or how rich and educated you are) and IQ. They used statistics to analyze the differences between identical twins, who share all DNA, and fraternal twins, who share only some.

When psychologists first started studying twins, they found identical twins much more likely to have similar IQs than fraternal ones. They concluded that IQ was highly “heritable”—due to genetic differences. But those were all high SES twins. Erik Turkheimer of the University of Virginia and his colleagues discovered that the picture was very different for poor, low SES, twins. For these children, there was very little difference between identical and fraternal twins: IQ was hardly heritable at all. Differences in the environment, like whether you lucked out with a good teacher, seemed to be much more important.

In the new study the Bates team found this was even true when those children grew up. This might seem paradoxical—after all, your DNA stays the same no matter how you are raised. The explanation is that IQ is influenced by education. Historically, absolute IQ scores have risen substantially as we’ve changed our environment so that more people go to school longer.

Richer children all have similarly good educational opportunities, so that genetic differences become more apparent. And since richer children have more educational choice, they (or their parents) can choose environments that accentuate and amplify their particular skills. A child who has genetic abilities that make her just slightly better at math may be more likely to take a math class, and so become even better at math.

But for poor children haphazard differences in educational opportunity swamp genetic differences. Ending up in a really terrible school or one a bit better can make a big difference. And poor children have fewer opportunities to tailor their education to their particular strengths.

How much your genes shape your intelligence depends on whether you live in a world with no schooling at all, a world where you need good luck to get a good education, or a world with rich educational possibilities. If we could change the world for the PKU babies, we can change it for the next generation of poor children, too.

EVEN YOUNG CHILDREN ADOPT ARBITRARY RITUALS

Human beings love rituals. Of course, rituals are at the center of religious practice. But even secularists celebrate the great transitions of life with arbitrary actions, formalized words and peculiar outfits. To become part of my community of hardheaded, rational, scientific Ph.D.s., I had to put on a weird gown and even weirder hat, walk solemnly down the aisle of a cavernous building, and listen to rhythmically intoned Latin.

Our mundane actions are suffused with arbitrary conventions, too. Grabbing food with your hands is efficient and effective, but we purposely slow ourselves down with cutlery rituals. In fact, if you’re an American, chances are that you cut your food with your fork in your left hand, then transfer the fork to your right hand to eat the food, and then swap it back again. You may not even realize that you’re doing it. That elaborate fork and knife dance makes absolutely no sense.

But that’s the central paradox of ritual. Rituals are intentionally useless, purposely irrational. So why are they so important to us?

The cognitive psychologist Christine LeGare at the University of Texas at Austin has been trying to figure out where rituals come from and what functions they serve. One idea is that rituals declare that you are a member of a particular social group.

Everybody eats, but only Americans swap their knives and forks. (Several spy movies have used this as a plot point). Sharing your graduation ceremony marks you as part of the community of Ph.D.s. more effectively than the solitary act of finishing your dissertation.

The fact that rituals don’t make practical sense is just what makes them useful for social identification. If someone just puts tea in a pot and adds hot water then I know only that they are a sensible person who wants tea. If instead they kneel on a mat and revolve a special whisk a precise number of times, or carefully use silver tongs to drop exactly two lumps into a china cup, I can conclude that they are members of a particular aristocratic tea culture.

It turns out that rituals are deeply rooted and they emerge early. Surprisingly young children are already sensitive to the difference between purposeful actions and rituals, and they adopt rituals themselves.

In a new paper forthcoming in the Journal Cognition, LeGare and colleagues showed 3- to 6-year-old children a video of people performing a complicated sequence of eight actions with a mallet and a pegboard. Someone would pick up the mallet, place it to one side, push up a peg with her hand etc. Then the experimenters gave the children the mallet and pegboard and said, “Now it’s your turn.”

You could interpret this sequence of actions as an intelligent attempt to bring about a particular outcome, pushing up the pegs. Or you could interpret it as a ritual, a way of saying who you are.

Sometimes the children saw a single person perform the actions twice. Sometimes they saw two people perform the actions simultaneously. The identical synchronous actions suggested that the two people were from the same social group.

When they saw two people do exactly the same thing at the same time, the children produced exactly the same sequence of actions themselves. They also explained their actions by saying things like “I had to do it the way that they did.” They treated the actions as if they were a ritual.

When they saw the single actor, they were much less likely to imitate exactly what the other person did. Instead, they treated it like a purposeful action. They would vary what they did themselves to make the pegs pop up in a new way.

LeGare thinks that, from the time we are very young children, we have two ways of thinking about people—a “ritual stance” and an “instrumental stance.” We learn as much from the irrational and arbitrary things that people do, as from the intelligent and sensible ones.

DOES EVOLUTION WANT US TO BE UNHAPPY?

Samuel Johnson called it the vanity of human wishes, and Buddhists talk about the endless cycle of desire. Social psychologists say we get trapped on a hedonic treadmill. What they all mean is that we wish, plan and work for things that we think will make us happy, but when we finally get them, we aren’t nearly as happy as we thought we’d be.

Summer makes this particularly vivid. All through the busy winter I longed and planned and saved for my current vacation. I daydreamed about peaceful summer days in this beautiful village by the Thames with nothing to do but write. Sure enough, the first walk down the towpath was sheer ecstasy—but by the fifth, it was just another walk. The long English evenings hang heavy, and the damned book I’m writing comes along no more easily than it did in December.

This looks like yet another example of human irrationality. But the economist Arthur Robson has an interesting evolutionary explanation. Evolution faces what economists call a principal-agent problem. Evolution is the principal, trying to get organisms (its agents) to increase their fitness. But how can it get those dumb animals to act in accordance with this plan? (This anthropomorphic language is just a metaphor, of course—a way of saying that the fitter organisms are more likely to survive and reproduce. Evolution doesn’t have intentions.)

For simple organisms like slugs, evolution can build in exactly the right motivations (move toward food and away from light). But it is harder with a complicated, cognitive organism like us. We act by imagining many alternative futures and deciding among them. Our motivational system has to be designed so that we do this in a way that tends to improve our fitness.

Suppose I am facing a decision between two alternative futures. I can stay where I am or go on to the next valley where the river is a bit purer, the meadows a bit greener and the food a bit better. My motivational system ensures that when I imagine the objectively better future it looks really great, far better than all the other options—I’ll be so happy! So I pack up and move. From evolution’s perspective that is all to the good: My fitness has increased.

But now suppose that I have actually already made the decision. I am in the next valley. It does me no additional good to continue admiring the river, savoring the green of the meadow and the taste of the fruit. I acted, I have gotten the benefit, and feeling happy now is, from evolution’s perspective, just a superfluous luxury.

Wanting to be happy and imagining the happy future made me act in a way that really did make me better off; feeling happy now doesn’t help. To keep increasing my fitness, I should now imagine the next potential source of happiness that will help me to make the next decision. (Doesn’t that tree just over the next hill have even better fruit?)

It is as if every time we make a decision that actually makes us better off, evolution resets our happiness meter to zero. That prods us to decide to take the next action, which will make us even better off—but no happier.

Of course, I care about what I want, not what evolution wants. But what do I want? Should I try to be better off objectively even if I don’t feel any happier? After all, the Thames really is beautiful, the meadows are green, the food—well, it’s better in England than it used to be. And the book really is getting done.

Or would it be better to defy evolution, step off the treadmill of desire and ambition and just rest serenely at home in Buddhist contentment? At least we humans can derive a bit of happiness, however fleeting, from asking these questions, perhaps because the answers always seem to be just over the next hill.

WHY ARE SOME CHILDREN MORE RESILIENT

The facts are grimly familiar: 20% of American children grow up in poverty, a number that has increased over the past decade. Many of those children also grow up in social isolation or chaos. This has predictably terrible effects on their development.

There is a moral mystery about why we allow this to happen in one of the richest societies in history. But there is also a scientific mystery. It's obvious why deprivation hurts development. The mystery is why some deprived children seem to do so much better than others. Is it something about their individual temperament or their particular environment?

The pediatrician Tom Boyce and the psychologist Jay Belsky, with their colleagues, suggest an interesting, complicated interaction between nature and nurture. They think that some children may be temperamentally more sensitive than others to the effects of the environment—both good and bad.

They describe these two types of children as orchids and dandelions. Orchids grow magnificently when conditions are just right and wither when they aren't. Dandelions grow about the same way in a wide range of conditions. A new study by Elisabeth Conradt at Brown University and her colleagues provides some support for this idea.

They studied a group of "at risk" babies when they were just five months old. The researchers recorded their RSA (Respiratory Sinus Arrhythmia)—that is, how their heart rates changed when they breathed in and out. Differences in RSA are connected to differences in temperament. People with higher RSA—heart rates that vary more as they breathe—seem to respond more strongly to their environment physiologically.

Then they looked at the babies' environments. They measured economic risk factors like poverty, medical factors like premature birth, and social factors like little family and community support. Most importantly, they also looked at the relationships between the children and their caregivers. Though all the families had problems, some had fewer risk factors, and those babies tended to have more stable and secure relationships. In other families, with more risk factors, the babies had disorganized and difficult relationships.

A year later, the researchers looked at whether the children had developed behavior problems. For example, they recorded how often the child hurt others, refused to eat or had tantrums. All children do things like this sometimes, but a child who acts this way a lot is likely to have trouble later on.

Finally, they analyzed the relationships among the children's early physiological temperament, their environment and relationships, and later behavior problems. The lower-RSA children were more like dandelions. Their risky environment did hurt them; they had more behavior problems than the average child in the general population, but they seemed less sensitive to variations in their environment. Lower-RSA children who grew up with relatively stable and secure relationships did no better than low-RSA children with more difficult lives.

The higher-RSA children were more like orchids. For them, the environment made an enormous difference. High-RSA children who grew up with more secure relationships had far fewer behavior problems than high-RSA children who grew up with difficult relationships. In good environments, these orchid children actually had fewer behavior problems than the average child. But they tended to do worse than average in bad environments.

From a scientific perspective, the results illustrate the complexity of interactions between nature and nurture. From a moral and policy perspective, all these children, dandelions and orchids both, need and deserve a better start in life. Emotionally, there is a special poignancy about what might have been. What could be sadder than a withered orchid?

MORAL PUZZLES KIDS STRUGGLE WITH

Here's a question. There are two groups, Zazes and Flurps. A Zaz hits somebody. Who do you think it was, another Zaz or a Flurp?

It's depressing, but you have to admit that it's more likely that the Zaz hit the Flurp. That's an understandable reaction for an experienced, world-weary reader of The Wall Street Journal. But here's something even more depressing—4-year-olds give the same answer.

In a 2012 study, 4-year-olds predicted that people would be more likely to harm someone from another group than from their own group.

In my last column, I talked about some disturbing new research showing that preschoolers are already unconsciously biased against other racial groups. Where does this bias come from?

Marjorie Rhodes at New York University argues that children are "intuitive sociologists" trying to make sense of the social world. We already know that very young children make up theories about everyday physics, psychology and biology. Dr. Rhodes thinks that they have theories about social groups, too.

In 2012 she asked young children about the Zazes and Flurps. Even 4-year-olds predicted that people would be more likely to harm someone from another group than from their own group. So children aren't just biased against other racial groups: They also assume that everybody else will be biased against other groups. And this extends beyond race, gender and religion to the arbitrary realm of Zazes and Flurps.

In fact, a new study in Psychological Science by Dr. Rhodes and Lisa Chalik suggests that this intuitive social theory may even influence how children develop moral distinctions.

Back in the 1980s, Judith Smetana and colleagues discovered that very young kids could discriminate between genuinely moral principles and mere social conventions. First, the researchers asked about everyday rules—a rule that you can't be mean to other children, for instance, or that you have to hang up your clothes. The children said that, of course, breaking the rules was wrong. But then the researchers asked another question: What would you think if teachers and parents changed the rules to say that being mean and dropping clothes were OK?

Children as young as 2 said that, in that case, it would be OK to drop your clothes, but not to be mean. No matter what the authorities decreed, hurting others, even just hurting their feelings, was always wrong. It's a strikingly robust result—true for children from Brazil to Korea. Poignantly, even abused children thought that hurting other people was intrinsically wrong.

This might leave you feeling more cheerful about human nature. But in the new study, Dr. Rhodes asked similar moral questions about the Zazes and Flurps. The 4-year-olds said it would always be wrong for Zazes to hurt the feelings of others in their group. But if teachers decided that Zazes could hurt Flurps' feelings, then it would be OK to do so. Intrinsic moral obligations only extended to members of their own group.

The 4-year-olds demonstrate the deep roots of an ethical tension that has divided philosophers for centuries. We feel that our moral principles should be universal, but we simultaneously feel that there is something special about our obligations to our own group, whether it's a family, clan or country.

"You've got to be taught before it's too late / Before you are 6 or 7 or 8 / To hate all the people your relatives hate," wrote Oscar Hammerstein. Actually, though, it seems that you don't have to be taught to prefer your own group—you can pick that up fine by yourself. But we do have to teach our children how to widen the moral circle, and to extend their natural compassion and care even to the Flurps.

The facts are grimly familiar: 20% of American children grow up in poverty, a number that has increased over the past decade. Many of those children also grow up in social isolation or chaos. This has predictably terrible effects on their development.

There is a moral mystery about why we allow this to happen in one of the richest societies in history. But there is also a scientific mystery. It's obvious why deprivation hurts development. The mystery is why some deprived children seem to do so much better than others. Is it something about their individual temperament or their particular environment?

HOW THE BRAIN REALLY WORKS

For the last 20 years neuroscientists have shown us compelling pictures of brain areas "lighting up" when we see or hear, love or hate, plan or act. These studies were an important first step. But they also suggested a misleadingly simple view of how the brain works. They associated specific mental abilities with specific brain areas, in much the same way that phrenology, in the 19th century, claimed to associate psychological characteristics with skull shapes.

Most people really want to understand the mind, not the brain. Why do we experience and act on the world as we do? Associating a piece of the mind with a piece of the brain does very little to answer that question. After all, for more than a century we have known that our minds are the result of the stuff between our necks and the tops of our heads. Just adding that vision is the result of stuff at the back and that planning is the result of stuff in the front, it doesn't help us understand how vision or planning work.

But new techniques are letting researchers look at the activity of the whole brain at once. What emerges is very different from the phrenological view. In fact, most brain areas multitask; they are involved in many different kinds of experiences and actions. And the brain is dynamic. It can respond differently to the same events in different times and circumstances.

A new study in Nature Neuroscience by Jack L. Gallant, Tolga Çukur and colleagues at the University of California, Berkeley, dramatically illustrates this new view. People in an fMRI scanner watched a half-hour-long sequence combining very short video clips of everyday scenes. The scientists organized the video content into hundreds of categories, describing whether each segment included a plant or a building, a cat or a clock.

Then they divided the whole brain into small sections with a three-dimensional grid and recorded the activity in each section of the grid for each second. They used sophisticated statistical analyses to find the relationship between the patterns of brain activity and the content of the videos.

The twist was that the participants either looked for human beings in the videos or looked for vehicles. When they looked for humans, great swaths of the brain became a "human detector"—more sensitive to humans and less sensitive to vehicles. Looking for vehicles turned more of the brain into a "vehicle detector." And when people looked for humans their brains also became more sensitive to related objects, like cats and plants. When they looked for vehicles, their brains became more sensitive to clocks and buildings as well.

In fact, the response patterns of most brain areas changed when people changed the focus of their attention. Something as ineffable as where you focus your attention can make your whole brain work differently.

People often assume that knowing about the brain is all that you need to explain how the mind works, so that neuroscience will replace psychology. That may account for the curious popular enthusiasm for the phrenological "lighting up" studies. It is as if the very thought that something psychological is "in the brain" gives us a little explanatory frisson, even though we have known for at least a century that everything psychological is "in the brain" in some sense. But it would be just as accurate to say that knowing about the mind explains how the brain works.

The new, more dynamic picture of the brain makes psychology even more crucial. The researchers could only explain the very complex pattern of brain activity by relating it to what they knew about categorization and attention. In the same way, knowing the activity of every wire on every chip in my computer wouldn't tell me much if I didn't also know the program my machine was running.

Neuroscience may be sexier than psychology right now, and it certainly has a lot more money and celebrity. But they really cannot get along without each other.

PREFRONTAL CONTROL AND INNOVATION

Quick—what can you do with Kleenex? Easy, blow your nose. But what can you do with Kleenex that no one has ever done before? That's not so easy. Finally a bright idea pops up out of the blue—you could draw a face on it, put a string around the top and make it into a cute little Halloween ghost!

Why is thinking outside of the Kleenex box so hard? A study published in February suggests that our much-lauded prefrontal brain mechanisms for control and focus may actually make it more difficult to think innovatively.

The comedian Emo Philips said that he thought his brain was the most fascinating organ in his body—until he realized who was telling him this. Perhaps for similar reasons, the control system of the brain, which includes areas like the left lateral prefrontal cortex, gets particularly good press. It's like the brain's chief executive officer, responsible for long-term planning, focusing, monitoring and distraction-squelching (and apparently PR too). But there may be a down side to those "executive functions." Shutting down prefrontal control may actually help people get to unusual ideas like the Kleenex ghost.

Earlier studies used fMRI imaging to see which parts of the brain are active when we generate ideas. In 2008 Charles Limb at Johns Hopkins University and Alan Braun at the National Institutes of Health reported how they got jazz musicians to either play from a memorized score or improvise, and looked at their brains. Some "control" parts of the prefrontal cortex shut down, deactivated, during improvisation but not when the musicians played a memorized score. Dr. Braun and colleagues later found the same effect with freestyle rappers—improvisational genius is not limited by baby-boomer taste.

But it's important to remember that correlation is not causation. How could you prove that the frontal deactivation really did make the improvisers innovate? You'd need to show that if you deactivate those brain areas experimentally people will think more innovatively. Sharon Thompson-Schill at the University of Pennsylvania and colleagues did that in the new study.

They used a technique called transcranial direct current stimulation, or tDCS. If you pass a weak electrical current through part of the brain, it temporarily and safely disrupts neural activity. The researchers got volunteers to think up either ordinary or unusual uses for everyday objects like Kleenex. While the participants were doing this task, the scientists either disrupted their left prefrontal cortex with tDCS or used a sham control procedure. In the control, the researchers placed the electrodes in just the same way but surreptitiously turned off the juice before the task started.

Both groups were equally good at thinking up ordinary uses for the objects. But the volunteers who got zapped generated significantly more unusual uses than the unzapped control-group thinkers, and they produced those unusual uses much faster.

Portable frontal lobe zappers are still (thankfully) infeasible. But we can modify our own brain functions by thinking differently—improvising, freestyling, daydreaming or some types of meditation. I like hanging out with 3-year-olds. Preschool brains haven't yet fully developed the prefrontal system, and young kids' free-spirited thinking can be contagious.

There's a catch, though. It isn't quite right to say that losing control makes you more creative. Centuries before neuroscience, the philosopher John Locke distinguished two human faculties, wit and judgment. Wit allows you to think up wild new ideas, but judgment tells you which ideas are actually worth keeping. Other neuroscience studies have found that the prefrontal system re-engages when you have to decide whether an unlikely answer is actually the right one.

Yes—you could turn that Kleenex into an adorable little Halloween ghost. But would that be the aesthetically responsible thing to do? Our prefrontal control systems are the sensible parents of our inner 3-year-olds. They keep us from folly, even at the cost of reining in our wit.

HELPLESS BABIES AND SMART GROWN-UPS

Why are children so, well, so helpless? Why did I spend a recent Sunday morning putting blueberry pancake bits on my 1-year-old grandson's fork and then picking them up again off the floor? And why are toddlers most helpless when they're trying to be helpful? Augie's vigorous efforts to sweep up the pancake detritus with a much-too-large broom ("I clean!") were adorable but not exactly effective.

This isn't just a caregiver's cri de coeur—it's also an important scientific question. Human babies and young children are an evolutionary paradox. Why must big animals invest so much time and energy just keeping the little ones alive? This is especially true of our human young, helpless and needy for far longer than the young of other primate

One idea is that our distinctive long childhood helps to develop our equally distinctive intelligence. We have both a much longer childhood and a much larger brain than other primates. Restless humans have to learn about more different physical environments than stay-at-home chimps, and with our propensity for culture, we constantly create new social environments. Childhood gives us a protected time to master new physical and social tools, from a whisk broom to a winning comment, before we have to use them to survive.

The usual museum diorama of our evolutionary origins features brave hunters pursuing a rearing mammoth. But a Pleistocene version of the scene in my kitchen, with ground cassava roots instead of pancakes, might be more accurate, if less exciting.

Of course, many scientists are justifiably skeptical about such "just-so stories" in evolutionary psychology. The idea that our useless babies are really useful learners is appealing, but what kind of evidence could support (or refute) it? There's still controversy, but two recent studies at least show how we might go about proving the idea empirically.

One of the problems with much evolutionary psychology is that it just concentrates on humans, or sometimes on humans and chimps. To really make an evolutionary argument, you need to study a much wider variety of animals. Is it just a coincidence that we humans have both needy children and big brains? Or will we find the same evolutionary pattern in animals who are very different from us? In 2010, Vera Weisbecker of Cambridge University and a colleague found a correlation between brain size and dependence across 52 different species of marsupials, from familiar ones like kangaroos and opossums to more exotic ones like quokkas.

Quokkas are about the same size as Virginia opossums, but baby quokkas nurse for three times as long, their parents invest more in each baby, and their brains are twice as big.

But do animals actually use their big brains and long childhoods to learn? In 2011, Jenny Holzhaider of the University of Auckland, New Zealand, and her colleagues looked at an even more distantly related species, New Caledonian crows. These brilliant big-brained birds make sophisticated insect-digging tools from palm leaves—and are fledglings for much longer than not-so-bright birds like chickens.

At first, the baby crows are about as good at digging as my Augie is at sweeping—they hold the leaves by the wrong end and trim them into the wrong shape. But the parents tolerate this blundering and keep the young crows full of bugs (rather than blueberries) until they eventually learn to master the leaves themselves.

Studying the development of quokkas and crows is one way to go beyond just-so stories in trying to understand how we got to be human. Our useless, needy offspring may be at least one secret of our success. The unglamorous work of caregiving may give human beings the chance to figure out just how those darned brooms work.