As a scientist, I was very aware that watching a baby’s brain develop feels as if you have a front-row seat to a biological Big Bang. The brain starts out as a single cell in the womb, quiet as a secret. Within a few weeks, it is pumping out nerve cells at the astonishing rate of 8,000 per second. Within a few months, it is on its way to becoming the world’s finest thinking machine.

The great thing about science is that it takes no sides—and no prisoners. Once you know which research to trust, the big picture emerges and myths fade away. To gain my trust, research must pass my “grump factor.” To make it into this book, studies must first have been published in the refereed literature and then successfully replicated. Some results have been confirmed dozens of times. Where I make an exception for cutting-edge research, reliable but not yet fully vetted by the passage of time, I will note it.

Even if all brains were wired identically and all parents behaved in a cookie-cutter fashion, a great deal of current research would still be flawed (or, at best, preliminary). Most of the data we have are associative, not causal. Why is that a problem? Two things can be associated without one causing the other. For example, it is true that all children who throw temper tantrums also urinate—the association is 100 percent—but that doesn’t mean urination leads to temper tantrums. The ideal research would be to a) find the behavioral secret sauce that makes smart or happy or moral kids who they are, b) discover parents who were missing the secret sauce and give it to them, and c) measure the kids 20 years later to see how they turned out. That sounds not only expensive but impossible. This is why most research we have about parenting is associative, not causal. But these data will be shared in the spirit that the perfect should not be the enemy of the good.

A third-grade boy comes home and hands his father his report card. His father looks at it and says, “How do you explain these D’s and F’s? The boy looks up at him and says, “You tell me: Is it nature or nurture?” I was once at a lively, noisy science fair with my own third-grade son, and we were touring some of his classmates efforts. Several experiments involved seeds, soil, and growth curves. One memorable little girl took great pains to explain to us that her seeds had started with identical DNA. She had planted one in a nutrient-rich soil and watered it carefully. She had planted the other in a nutrient-poor soil and watered it carefully, too. Time passed. The seed nurtured with terrific soil made a terrific plant, which she proudly let me hold in my hands. The seed nurtured in poor soil made a pitiful, withered plant. She let me hold that, too. Her point was that the seed material provided identical growth opportunities for both plants, but that starting equal was not enough.“You need both seed and soil”, she explained to me—nature and nurture—to get the desired results.

In fact, some evolutionary biologists believe this is why morning sickness still persists in human pregnancies. Morning sickness, which can last the entire day (and, for some women, the entire pregnancy), makes a woman stick to a bland, boring diet—if she eats much at all. This avoidance strategy would have kept our maternal ancestors away from the natural toxins in exotic or spoiled foods in the wild, unregulated menu of the Pleistocene diet. The accompanying fatigue would keep women from engaging in physical activity risky enough to harm the baby. Researchers now think it could make the baby smarter, too.

Believe it or not, no commercial product has ever been shown in a scientifically responsible manner (or even in an irresponsible non-scientific manner) to do anything to improve the brain performance of a developing fetus. There have been no double-blind, randomized experiments whose independent variable was the presence or absence of the gadget. No rigorous studies showing that an in utero education curriculum produced long-term academic benefits when the child entered high school. No twins-separated-at-birth studies attempting to tease out nature and nurture components of a given product’s effects. That includes the in utero university. And the in utero Mozart.

Researchers have isolated three toxic types. Their common characteristic: that you feel out of control over the bad stuff coming at you. As stress moves from moderate to severe, and from acute to chronic, this loss of control turns catastrophic and begins to affect baby. Here are the bad types of stress:

Lots of research has gone into trying to understand how maternal stress affects brain development. And we have begun to answer this question at the most intimate level possible: the level of cell and molecule. For this progress we mostly can thank the klutzy researcher Hans Selye. He is the founder of the modern concept of stress. As a young scientist, Selye would grind up “endocrine extracts”, which presumably contained active stress hormones, and inject them into rats to see what the rats would do. He was not good at it. His lab technique, to put it charitably, was horrible. He often dropped the poor lab animals he was attempting to inject. He had to chase them around with a broom, trying to get them back into their cages. Not surprisingly, the rats became anxious in his presence. Selye observed that he could create this physiological response just by showing up. His main job was to inject some animals with endocrine extract and others, in the control group, with saline. But he was perplexed to discover that both were getting ulcers, losing sleep, and becoming more susceptible to infectious diseases. After many observations, he concluded that anxiety was producing the effect, a concept surprisingly new at the time. If the rats couldn’t remove the source of anxiety or cope with it once it arrived, he found, it could lead to disease and other consequences. To describe the phenomenon, Selye eventually coined the term “stress.” Selye’s insight led to that rarest of all findings: the link between visible behaviors and invisible molecular processes. Selye’s work gave the research community permission to investigate how stressful perceptions could influence biological tissues, including brain development. We know a lot about how stress hormones affect growing neural tissues, including a baby’s, thanks to this pioneering insight. Though most of the research was done on rats, many of the same key processes have been found in humans, too.

Does that mean exercise should be a part of human pregnancies? Evidence suggests the answer is yes. The first benefit is a practical one, having to do with labor. Many women report that giving birth is both the most exhilarating experience of their lives and the most painful. But women who exercise regularly have a much easier time giving birth than obese women. For fit women, the second stage of labor—that painful phase where you have to do a lot of pushing—lasts an average of 27 minutes. Physically unfit women had to push for almost an hour, some far longer. Not surprisingly, fit women perceived this stage as being far less painful. And, because the pushing phase was so much shorter, their babies were less likely to experience brain damage from oxygen deprivation. If you are afraid of labor, you owe it yourself to become as fit as possible going into it. And the reasons are argued purely from the Serengeti.

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What is the proper balance? Four words: moderate, regular aerobic exercise. For most women, that means keeping your heart rate below 70 percent of its maximal rate (which is 220 beats per minute minus your age), then slowing things down as the due date approaches. But you should exercise. As long as you don’t have obstetric or other medical complications, the American College of Obstetricians recommends 30 minutes or more of moderate exercise per day.

A bracingly cold glass of water was thrown on this Eisenhoweresque perception by famed sociologist E.E. LeMasters. In 1957, he published a research paper showing that 83 percent of new parents experienced a moderate to severe crisis in the marriage during the transition to parenthood. These parents became increasingly hostile toward each other in the first year of the baby’s life. The majority were having a hard time.

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There is hope. We know four of the most important sources of marital conflict in the transition to parenthood: sleep loss, social isolation, unequal workload, and depression. We will examine each. Couples who make themselves aware of these can become vigilant about their behavior, and they tend to do better. We also know that not every marriage follows this depressing course of events. Couples going into pregnancy with strong marital bonds withstand the gale forces of baby’s first year better than those who don’t. Those who carefully plan for their children prior to pregnancy do, too. In fact, one of the biggest predictors of marital bliss appears to be the agreement to have kids in the first place. One large study examined couples where both parties wanted kids versus couples where only one did. If both partners wanted the child, very few divorced, and marital happiness either stayed the same or increased in the baby’s first year of life.

Even in an emotionally stable home, one without regular marital hostility, there will be fights. Fortunately, research shows that the amount of fighting couples do in front of their children is less damaging than the lack of reconciliation the kids observe. Many couples will fight in front of their children but reconcile in private. This skews a child’s perceptions, even at early ages, for the child always sees the wounding but never the bandaging. Parents who practice bandaging each other deliberately—and explicitly—after a fight allow their children to model both how to fight fair and how to make up.

                • sleep loss

Birth—before the advent of modern medicine—often resulted in the mother’s death. Though no one knows the true figure, estimates run as high as 1 in 8. Tribes with females who could quickly relate to and trust nearby females were more likely to survive. Older females, with the wisdom of their prior birthing experiences, could care for new mothers. Women with kids could provide precious milk to a new baby if the birth mother died. Sharing and its accompanying social interactions thus provided a survival advantage, says anthropologist Sarah Hrdy (no, there’s no “a in her last name). She calls it “alloparenting.” Consistent with this notion is the finding that we are the only primates who regularly let others take care of our children.

Women spend a whopping 39 hours per week performing work related to child care. Today’s dad spends about half that—21.7 hours a week. This is usually couched as good news, too, for it is triple the amount of time guys spent with kids in the ’60s. Yet no one would call this equal, either. It is also still true that about 40 percent of dads spend two hours or less per workday with their kids, and 14 percent spend less than an hour. This imbalance in workload—along with financial conflicts, which may be related—is one of the most frequently cited sources of marital conflict. It plays a significant factor in a woman’s opinion of the man she married, especially if he pulls the “I am the breadwinner card” as Melanie’s husband did. The financials speak loudly here. A typical stay-at-home mom works 94.4 hours per week. If she were paid for her efforts, she would earn about $117,000 per year. (This is a calculation of hourly compensation and time spent per task for the 10 job titles moms typically perform in American households, including housekeeper, van driver, day-care provider, staff psychologist, and chief executive officer.) Most guys do not spend 94.4 hours a week at their jobs. And 99 percent of them earn less than $117,000 per year.

IQ is malleable. IQ has been shown to vary over one’s life span, and it is surprisingly vulnerable to environmental influences. It can change if one is stressed, old, or living in a different culture from the testing majority. A child’s IQ is influenced by his or her family, too. Growing up in the same household tends to increase IQ similarities between siblings, for example. Poor people tend to have significantly lower IQs than rich people. And if you are below a certain income level, economic factors will have a much greater influence on your child’s IQ than if your child is middle class. A child born in poverty but adopted into a middle-class family will on average gain 12 to 18 points in IQ.

Thousands of experiments confirm that babies learn about their environment through a series of increasingly self-corrected ideas. They experience sensory observations, make predictions about what they observe, design and deploy experiments capable of testing their predictions, evaluate their tests, and add that knowledge to a self-generated, growing database. The style is naturally aggressive, wonderfully flexible, and annoyingly persistent. They use fluid intelligence to extract information, then crystallize it into memory. Nobody teaches infants how to do this, yet they do it all over the world. This hints at the behavior’s strong evolutionary roots. They are scientists, as their parents suspected all along.

Gestures and speech used similar neural circuits as they developed in our evolutionary history. University of Chicago psycholinguist David McNeill was the first to suggest this. He thought nonverbal and verbal skills might retain their strong ties even though they’ve diverged into separate behavioral spheres. He was right. Studies confirmed it with a puzzling finding: People who could no longer move their limbs after a brain injury also increasingly lost their ability to communicate verbally. Studies of babies showed the same direct association. We now know that infants do not gain a more sophisticated vocabulary until their fine-motor finger control improves. That’s a remarkable finding. Gestures are “windows into thought processes,” McNeill says. Could learning physical gestures improve other cognitive skills? One study hints that it could, though more work needs to be done. Kids with normal hearing took an American Sign Language class for nine months, in the first grade, then were administered a series of cognitive tests. Their attentional focus, spatial abilities, memory, and visual discrimination scores improved dramatically—by as much as 50 percent—compared with controls who had no formal instruction.

Studies show that, compared with controls, kids allowed a specific type of open-ended play time were:

Vygotsky was one of the few researchers of his era to study dramatic play in children. He predicted that the ability of the under-5 crowd to engage in imaginative activities was going to be a better gauge of academic success than any other activity—including quantitative and verbal competencies. The reason, Vygotsky believed, was that such engagement allowed children to learn how to regulate their social behaviors. Hardly the carefree activity we think of in the United States, Vygotsky saw imaginative play as one of the most tightly restricting behaviors children experience. If little Sasha was going to be a chef, he would have to follow the rules, expectations, and limitations of “chef-ness”. If this imaginative exercise included friends, they would have to follow the rules, too. They might push and pull and argue with each other until they agreed on what those rules were and how they should be executed. That’s how self-control developed, he posited. In a group setting, such a task is extremely intellectually demanding, even for adults. If this sounds like a prelude to the more modern notion of executive function, you are right on the money. Vygotksy’s followers showed that children acting out imaginative scenes controlled their impulses much better than they did in non-MDP situations. While other parts of Vygotsky’s work are starting to show some intellectual arthritis, his ideas on self-regulation have held up well.

On the successful completion of a test, they should not have said,“I’m so proud of you. You’re so smart. They should have said, “I’m so proud of you. You must have really studied hard”. This appeals to controllable effort rather than to unchangeable talent. It’s called “growth mindset” praise. More than 30 years of study show that children raised in growth-mindset homes consistently outscore their fixed-mindset peers in academic achievement. They do better in adult life, too. That’s not surprising. Children with a growth mindset tend to have a refreshing attitude toward failure. They do not ruminate over their mistakes. They simply perceive errors as problems to be solved, then go to work. In the lab as well as in school, they spend much more time banging away at harder tasks than fixed-mindset students. They solve those problems more often, too. Kids regularly praised for effort successfully complete 50 percent to 60 percent more hard math problems than kids praised for intelligence. Carol Dweck, a noted researcher in the field, would check in on students taking her tests. Comments like “I should slow down and try to figure this out” were common, as was the delightful “I love a challenge.” Because they believe mistakes occur from of lack of effort, not from a lack of ability, the kids realize mistakes can be remedied simply by applying more cognitive elbow grease.

1. Keep the TV off before the child turns 2. I know this is tough to hear for parents who need a break. If you can’t turn it off—if you haven’t created those social networks that can allow you a rest—at least limit your child’s exposure to TV. We live in the real world, after all, and an irritated, overextended parent can be just as harmful to a child’s development as an annoying purple dinosaur. 2. After age 2, help your children choose the shows (and other screen-based exposures) they will experience. Pay special attention to any media that allow intelligent interaction. 3. Watch the chosen TV show with your kids, interacting with the media, helping them to analyze and think critically about what they just experienced. And rethink putting a TV in the kids room: Kids with their own TVs score an average of 8 points lower on math and language-arts tests than those in households with TVs in the family room.

In the mid-1960s, Baumrind published her ideas on parenting, a framework so robust that researchers still use it today. You can think of her ideas as the four styles of child-rearing. Baumrind described two dimensions in parenting, each on a continuum:

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“I don’t like it, the 3-year-old muttered to herself as the guests left. Miserable throughout her older sister’s birthday party, she was now growing angry. “I want Ally’s doll, not this one!” Her parents had bought her a consolation present, but the strategy went down like a bomb. The girl threw her doll to the floor. “Ally’s doll! Ally’s doll!” She began to cry. You can imagine a parent making any of several choices in the face of this bubbling brew.

“You seem sad. Are you sad? is what the girl’s dad said. The little girl nodded, still angry, too. The dad continued. “I think I know why. You’re sad because Ally’s gotten all the presents. You only got one!” The little girl nodded again. “You want the same number and you can’t have it, and that’s unfair and that makes you sad.” The dad seemed to be pouring it on. “Whenever somebody gets something I want and I don’t, I get sad, too.” Silence.

Then the dad said the line most characteristic of a verbalizing parent. “We have a word for that feeling, honey”, he said. “Do you want to know what that word is?” She whimpered, “OK.” He held her in his arms. “We call it being jealous. You wanted Ally’s presents, and you couldn’t have them. You were jealous.” She cried softly but was beginning to calm down. “Jealous”, she whispered. “Yep”, Dad replied, “and it’s an icky feeling.” “I been jealous all day”, she replied, nestling into her daddy’s big strong arms.

This big-hearted father is good at a) labeling his feelings and b) teaching his daughter to label hers. He knows what sadness in his own heart feels like and announces it easily. He knows what sadness in his child’s heart looks like, and he is teaching her to announce it, too. He is also good at teaching joy, anger, disgust, concern, fear—the entire spectrum of his little girl’s experience.

Research shows that this labeling habit is a dominant behavior for all parents who raise happy children. Kids who are exposed to this parenting behavior on a regular basis become better at self-soothing, are more able to focus on tasks, and have more successful peer relationships. Sometimes knowing what to do is tougher than knowing what to say. But sometimes saying is all that’s needed.

[...}

Parents who raise kids like my friend Doug, the valedictorian, have this type of courage in spades. They are fearless in the face of raging floods of emotions from their child. They don’t try to shoot down emotions, ignore them, or let them have free reign over the welfare of the family. Instead, these parents get involved in their kids strong feelings. They have four attitudes toward emotions (yes, their meta-emotions):

• They do not judge emotions. • They acknowledge the reflexive nature of emotions. • They know that behavior is a choice, even though an emotion is not. • They see a crisis as a teachable moment.

10 years of music lessons There’s another powerful way to fine-tune a child’s hearing for the emotional aspects of speech: musical training. Researchers in the Chicago area showed that musically experienced kids—those who studied any instrument for at least 10 years, starting before age 7—responded with greased-lightning speed to subtle variations in emotion-laden cues, such as a baby’s cry. The scientists tracked changes in the timing, pitch, and timbre of the baby’s cry, all the while eavesdropping on the musician’s brainstem (the most ancient part of the brain) to see what happened. Kids without rigorous musical training didn’t show much discrimination at all. They didn’t pick up on the fine-grained information embedded in the signal and were, so to speak, more emotionally tone deaf. Dana Strait, first author of the study, wrote: “That their brains respond more quickly and accurately than the brains of non-musicians is something we’d expect to translate into the perception of emotion in other settings.” This finding is remarkably clear, beautifully practical, and a bit unexpected. It suggests that if you want happy kids later in life, get them started on a musical journey early in life. Then make sure they stick with it until they are old enough to start filling out their applications to Harvard, probably humming all the way.

Kohlberg outlined a progressive process for moral development:

1. Avoiding punishment. Moral reasoning starts out at a fairly primitive level, focused mostly on avoiding punishment. Kohlberg calls this stage pre-conventional moral reasoning.

2. Considering consequences. As a child’s mind develops, she begins to consider the social consequences of her behaviors and starts to modify them accordingly. Kohlberg terms this conventional moral reasoning.

3. Acting on principle. Eventually, the child begins to base her behavioral choices on well-thought-out, objective moral principles, not just on avoidance of punishment or peer acceptance. Kohlberg calls this coveted stage post-conventional moral reasoning. One could argue that the goal of any parent is to land here.

Over the years, many studies have been devoted to assessing the usefulness of this method, often coming to confusing—even opposing—conclusions. One of the latest lightning rods is a five-year review of the research literature by a committee of child development specialists sponsored by the American Psychological Association. The committee came out against corporeal punishment, finding evidence that spanking caused more behavioral problems than other types of punishment, producing more aggressive, more depressed, more anxious children with lower IQs. A spring 2010 study, led by Tulane University School of Public Health researcher Catherine Taylor, confirms the findings. It found that 3-year-olds who were spanked more than twice in the month prior to the study were 50 percent more likely to be aggressive by age 5, even when controlling for differing levels of aggression among kids and for maternal depression, alcohol or drug use, or spousal abuse.

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As researcher Murray Straus noted in an interview with Scientific American Mind, the linkage between spanking and behavioral unpleasantness is more robust than the linkage between exposure to lead and lowered IQ. More robust, too, than the association between secondhand smoke and cancer. Few people argue about these associations; indeed, people win lawsuits with associative numbers in those health-related cases. So why is there so much controversy about whether to spank, when there should be none? Good question.

I do know that inductive parenting takes effort. Hitting a kid does not. In my opinion, hitting is a lazy form of parenting. If you’re wondering, my wife and I don’t do it.

As a new parent, you may feel sometimes that all children do is take from you, but it is just a form of giving in disguise. Kids present you with an ear infection, but what they are really giving you is patience. They present you with a tantrum, but they are really giving you the honor of witnessing a developing personality. Before you know it, you’ve raised up another human being. You realize what a great privilege it is to be a steward of another life.

I said that parenting is all about developing human brains, but my aim was inches too high. Parenting is all about developing human hearts.

For evolutionary reasons, human babies were never meant to be born and raised in isolation from a group. Psychotherapist Ruth Josselson believes it is especially important for young mothers to create and maintain an active social tribe after giving birth. There are two big problems with this suggestion: 1) Most of us don’t live in tribes, and 2) we move around so much that most of us don’t even live near our own families, our natural first tribal experience. The result is that many new parents live on the margins of their social lives. They don’t have a relative or trusted friend who can watch their kids while they take a shower, get some sleep, or make out with their spouses.

The solution is obvious: Reconstitute a vigorous social structure using whatever tools you have at hand.

Start forming one now, before the baby comes. There are many options. At the formal level, there are PEPS groups (Program for Early Parent Support) and churches and synagogues, all possessing built-in notions of community. Informally, you can host social get-togethers with your friends. Go out with other pregnant couples in Tribe Lamaze. Throw cooking parties, where you and your friends make a bunch of freezer meals. Having a 50-day meal supply all ready to eat before baby comes home is one of the best gifts you can give any prospective parent. Doing another 50 after baby arrives is a great way to cement your community.

Knowing full well the need for our kids to be digitally conversant, yet fully aware of the dangers, we came up with a few rules as our boys became preschoolers. First, my wife and I divided digital experiences into categories. Two of the categories involved things necessary for school work or for learning about computers: word processing and graphics programs, web-based research projects, programming, and so on. The boys were allowed to do these as homework required.

Recreational experiences—digital games, certain types of web surfing, and our Wii gaming system—we called Category I. They were off limits except under one condition. Our sons could “buy a certain amount of Category I time. The currency? The time spent reading an actual book. Every hour spent reading could purchase a certain amount of Category I time. This was added up and could be “spent” on weekends after homework was done. This worked for us. The kids picked up a reading habit, could do the digital work necessary for their futures, and were not completely locked out of the fun stuff.

In front of your children, verbally speculate about other people’s perspectives in everyday situations. You can wonder why the person behind you in line at a grocery is so impatient or what the joke is when a stranger talking on a cell phone laughs. It’s a natural way to practice seeing other people’s points of view—the basis of empathy.

Guide your child toward a $50,000 career

Effective punishment FIRST

In 1962, researchers wanted to test the effects of an early-childhood preschool training program they had designed. Kids in Ypsilanti, Michigan, were randomly assigned to one of two groups. The first attended the preschool program (which eventually became a model for other preschool programs nationwide, including Head Start). The second group did not. The differences powerfully illustrate the importance of a child’s early years. The kids in the program academically outperformed the controls in virtually every way you can measure performance, from IQ and language tests in the early years to standardized achievement assessments and literacy exams in the later years. More graduated from high school (84 percent vs. 32 percent for the girls). Not surprisingly, they were more likely to attend college. The kids who were not in the program were four times more likely to require treatment for a mental-health problem (36 percent vs. 8 percent). They were twice as likely to repeat a grade (41 percent vs. 21 percent). As adults, those who had been in the program were less likely to commit crimes and more likely to hold steady jobs. They made more money, more often had a savings account, and were more likely to own a home. Economists calculated that the return on society’s investment in such a program was 7 to 10 percent, about what you’d historically get in the stock market. Some estimate a substantially higher return: $16 for every tax dollar invested in early childhood.

If survival is the brain’s most important priority, safety is the most important expression of that priority. This is the lesson Harlow’s iron maidens teach us. Babies are completely at the mercy of the people who brought them into the world. This understanding has a behavioral blast radius in infants that obscures every other behavioral priority they have.

How do babies handle these concerns? By attempting to establish a productive relationship with the local power structures—you, in other words—as soon as possible. We call this attachment. During the attachment process, a baby’s brain intensely monitors the caregiving it receives. It is essentially asking such things as “Am I being touched? Am I being fed? Who is safe?” If the baby’s requirements are being fulfilled, the brain develops one way; if not, genetic instructions trigger it to develop in another way. It may be a bit disconcerting to realize, but infants have their parents behaviors in their sights virtually from the moment they come into this world. It is in their evolutionary best interests to do so, of course, which is another way of saying that they can’t help it. Babies have nowhere else to turn.

There’s a window of several years during which babies strive to create these bonds and establish perceptions of safety. If it doesn’t happen, they can suffer long-term emotional damage. In extreme cases, they can be scarred for life.

We know this because of a powerful—and heartbreaking—story from Communist Romania, discovered circa 1990 by Western reporters. In 1966, in an effort to boost the country’s low birthrate, the dictator Nicolae Ceausescu banned both contraception and abortion and taxed those who were childless after age 25—whether married, single, or infertile. As the birthrate rose, so did poverty and homeless-ness. Children were often simply abandoned. Ceausescu’s response was to create a gulag of state orphanages, with children warehoused by the thousands.

The orphanages soon were stripped of resources as Ceausescu began exporting most of Romania’s food and industry to repay the country’s crippling national debt. The scenes in these orphanages were shocking. Babies were seldom held or given deliberate sensory stimulation. Many were found tied to their beds, left alone for hours or days, with bottles of gruel propped haphazardly into their mouths. Many infants stared blankly into space. Indeed, you could walk into some of these hundred-bed orphanages and not hear a sound. Blankets were covered in urine, feces, and lice. The childhood mortality rate in these institutions was sickening, termed by some Westerners “pediatric Auschwitz.”

Horrible as these conditions were, they created a real opportunity to investigate—and perhaps treat—large groups of severely traumatized children. One remarkable study involved Canadian families who adopted some of these infants and raised them back home. As the adopted children matured, researchers could easily divide them into two groups. One group seemed remarkably stable. Social behavior, stress responses, grades, medical issues—all were indistinguishable from healthy Canadian controls. The other group seemed just as remarkably troubled. They had more eating problems, got sick more often, and exhibited increasingly aggressive antisocial behaviors. The independent variable? The age of adoption.

If the children were adopted before the fourth month of life, they acted like every other happy kid you know. If they were adopted after the eighth month of life, they acted like gang members. The inability to find safety through bonding, by a specific age in infancy, clearly caused immense stress to their systems. And that stress affected these children’s behavior years later. They may have been removed from the orphanages long ago, but they were never really free.

The more parents talk to their children, even in the earliest moments of life, the better their kids linguistic abilities become and the faster that improvement is achieved. The gold standard is 2,100 words per hour. The variety of the words spoken (nouns, verbs, and adjectives used, along with the length and complexity of phrases and sentences) is nearly as important as the number of words spoken. So is the amount of positive feedback. You can reinforce language skills through interaction: looking at your infant; imitating his vocalizations, laughter, and facial expressions; rewarding her language attempts with heightened attention. Children whose parents talked positively, richly, and regularly to them knew twice as many words as kids whose parents talked to them the least. When these kids entered the school system, their reading, spelling, and writing abilities soared above those of children in less verbal households. Even though babies don’t respond like adults, they are listening, and it is good for them.

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Educational psychologist William Fowler trained a group of parents to talk to their children in a particular fashion, following some of the guidelines mentioned above. The children spoke their first words between 7 and 9 months of age, some even speaking sentences at 10 months. They had conquered most of the basic rules of grammar by age 2, while the controls achieved a similar mastery around age 4. Longer-term studies showed that the kids did very well in school, including in math and science. By the time they entered high school, 62 percent of them were enrolled in gifted or accelerated programs. Critical parts of Fowler’s training program need further study, but his work is terrific. It adds to the overwhelming evidence that a whole lot of talking is like fertilizer for neurons.