The Nature of Nurture

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Such questions preoccupied Francis when she returned to school. She already knew that social, economic, and emotional deprivation could harm family relationships, and a resulting lack of nurturing could set up a certain type of brain biology for children. The young rats’ genes had been chemically repackaged in order to mobilize permanently against stress and routinely pump out high levels of hormones such as cortisol, in turn damaging learning capacity and heightening fearfulness. And yet, Francis was sure that the reactive behavior patterns apparently etched into the brain’s biochemistry could change. In working with troubled children and their mothers, for example, she had seen how transformative a simple thing like a weekend outing could be. The question was, how?

Francis set up experiments to investigate what could damp down the stress response in teenage rats. Enriched environments—cages with plenty of toys and social companionship—changed both hormone levels and behavior. Gene expression remained the same, however, suggesting that the rats compensated in some other way. To better understand what happens, Francis has begun a number of cross-disciplinary projects at Berkeley on stress response, decision making, and external influences on gene activity.

One of her closest collaborators is integrative biologist Daniela Kaufer, whose work documents the role of RNA—long dismissed as DNA’s poor sibling—in switching the functions for which DNA codes. Under stress, Kaufer has found, molecules outside the genome change the RNA in new ways, trimming and rearranging it to alter gene function.

Kaufer says that if researchers can break down the reprogramming in the brain caused by early-life trauma or stress, possible interventions may present themselves. Physical exercise, for instance, is known to reset the molecular machinery. Yoga, meditation, and sleep all can alter the stress response, muses the former yoga teacher.

For Francis, the study of how stress can work itself into our biological inheritance remains deeply personal. “I’m a product of all this stuff,” she says, referring to her hardscrabble beginnings back in Montreal. Americans, Francis contends, think poor people are poor because they make poor decisions. Francis believes the experience of her rats points to something very different.

Sally Lehrman has reported for Scientific American and the Peabody Award–winning, NPR-distributed series The DNA Files (www.dnafiles.org). Reprinted from California(March-April 2008), the alumni magazine of the University of California, Berkeley. Subscriptions: $19.95/yr. (6 issues) from Alumni House, Berkeley, CA 94720; www.californiamag.org.

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