Genetics Will Help Social Engineers Nurture the Brain's Nature
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By Gary Marcus

Los Angeles Times, Op-ed, April 21, 2004


The human brain has been described as everything from the "last frontier" and "biology's greatest challenge" to "the most elaborate structure in the known universe" and Woody Allen's "second-favorite organ."

With rapid advances in biotechnology and basic sciences such as genetics, neuroscience and psychology, we will soon have a radically improved understanding of the contribution of genes to the developing brain. Used wisely, that knowledge could lead to an entirely new approach to social intervention. But doing so will require overcoming some common misconceptions about how genes operate.

Genes are widely seen as either blueprints or deterministic dictators but, in fact, neither view is correct. A single organism's collection of genes — its genome — can lead to many different outcomes, depending on the environment surrounding that genome. The African butterfly Bicyclus anyana, for example, can take on two different forms — a colorful version in the rainy season and a dull brown version in the dry season — depending on how its genes are switched on and off.

The consequences of the responsiveness of genes to the environment may be even more profound in a human. A butterfly's coloration pattern may only be skin deep, but the switching of human genes in response to the environment may profoundly shape our personalities.

Contrary to our usual belief that genes force us toward one possibility rather than another, contemporary biology is revealing a different picture in which genes arm us with ways of responding to different environments. To take but one example, a recent study — still preliminary, but breathtaking in what it might mean — suggests that people who bear a particular version of an enzyme known as MAO-A (part of the serotonin pathway) are predisposed to violence, but only if raised in abusive environments. This particular version of MAO-A is better thought of not as a gene "for violence" but as a gene that leads its bearers to different kinds of strategies, depending on their environments.

Given that genes themselves are responsive to the environment, and responsive in different ways in different people, a bold new possibility suggests itself, akin to an idea that has taken hold in medicine under the name of pharmacogenetics. The idea behind pharmacogenetics is that different people respond differently to different drugs depending on their own individual chemistry; depending on your genes, one version of a drug may be more effective, another less so.

Doctors are already beginning to incorporate this sort of information into the prescription of certain powerful drugs, and they will do so more and more as our understanding of genes grows.

Just as pharmacogenetics tailors medical intervention to individual genetic profiles, a new field of "social-intervention genetics" could tailor social intervention to individual genetic profiles. For example, other things being equal, society would get the most for its social intervention buck by specifically offering certain social welfare programs to those with the predisposing form of the MAO-A gene. Genetic information should never be used to dictate who gets to (or, worse, doesn't get to) reproduce; nor should society mandatorily impose intervention where it is not wanted. But by helping to make social interventions available to those who need them most, our growing understanding of nature could help us get the most out of nurture.

Gary Marcus, an associate professor of psychology at New York University, is the author of "The Birth of the Mind: How a Tiny Number of Genes Creates the Complexity of Human Thought" (Basic Books, 2004).