Bringing Up Baby's Brain

Search for "parenting" on Amazon and you'll turn up more than 65,000 books peddling dos and don'ts for raising healthy, happy kids. We seem to believe that the right early experiences will turn our children into superstars; the wrong ones will damage them. But is there really a formula for perfect parenting? And how do our early experiences shape who we become?

At the annual meeting of the American Association for the Advancement of Science, running this weekend in Vancouver, researchers came together to share their research on how our earliest experiences--experiences we can't even remember--"wire" our brains and bodies to succeed or struggle in adult life.

In the 1950s and 1960s, psychologist Harry Harlow performed a series of influential but unsettling experiments on baby rhesus monkeys. He separated infant monkeys from their mothers and placed them in isolation with "surrogate" monkey moms--dolls made of terrycloth or wire, equipped to dispense milk but nothing else.

The monkeys grew up disturbed. When they were finally removed from isolation, many went into a "state of emotional shock," Harlow reported. Some refused food; they clutched and rocked. They did not play with other monkeys and could not form relationships with their peers. "Twelve months of isolation almost obliterated the animals socially," wrote Harlow.

Harlow's work has drawn sharp ethical criticism, and of course it is impossible to imagine performing any such experiment on human subjects. But, heartbreakingly, millions of children worldwide who are maltreated or abandoned or who lose their parents to violence or disease are unwitting "subjects" in just such a natural experiment. Many are ultimately raised in poorly staffed institutions where they receive little stimulation, follow fixed routines, and don't get compassionate care. These children typically have sharply lower IQ scores than their peers. Their growth is stunted and they struggle with language, social behavior, and forming attachments.

But how can we untangle nature from nurture in our understanding of these children? Were they "damaged goods" from the start, incapable of benefiting from compassionate care even if it were provided? And if a child should thrive after being adopted, would that be evidence of the reparative power of nurture--or evidence that adoptive parents naturally picked the most gifted and least impaired children?

This was the question the Bucharest Early Intervention Project, led up by Harvard professor Charles Nelson, set out to answer. More than one hundred institutionalized children in Bucharest were randomly assigned to either remain in their institutions or to live with foster families. (Foster homes were available for only half of the children, due to a cultural bias against adoption.) How would the fostered children fare compared to their institutionalized peers? And would they ever catch up with children who had never experienced life in an institution?

Nelson and his colleagues discovered that fostered kids could indeed thrive--their social skills improved, their IQs climbed--but the developmental window of opportunity did not remain open forever. The children saw substantive improvements only if they were placed in foster care before their second birthday, and the younger, the better.

This might seem obvious, but to policymakers in Romania, says Nelson, it was not initially so. The results of the study are informing how public health agencies worldwide will care for the estimated eight million children who are now living in institutional care.

Somehow, the conditions in institutions change the brains and bodies of young children. But how? At the Yerkes National Primate Research Center, Mar Sanchez is studying this question with Harlow's old subjects, rhesus monkeys. But these monkeys are not caged and separated from their mothers. It turns out that between two and five percent of female monkeys are naturally "bad mothers"--they abuse their babies, dragging them screaming across the ground, or they simply ignore them when they seek attention and comfort. These abused and rejected infants spend more time screaming and throwing tantrums than warmly-mothered monkeys; they respond anxiously to new or stressful situations. And, their levels of the stress hormone cortisol are chronically high.

Not all monkeys respond equally--genetic vulnerabilities (or sensitivities, if you like) seem to amplify the damaging effects of abuse and rejection. And, contrary to what you might expect, rejection is actually more destructive than abuse: Rejection was linked to low levels of serotonin in the brain and was the strongest predictor of whether a monkey would perpetuate the cycle of bad mothering in the next generation.

Of course, human kids are not rhesus monkeys. But to those perusing Amazon's virtual aisles in search of the formula for perfect parenting--those who fret about too much discipline or too little, about whether baby is getting too much television or too little Mozart--maybe there is some comfort here: As in so many other endeavors, the better part of success may be simply showing up.

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