The Complex Relationship Between Nature, Nurture, and Intelligence

After the Bell Curve
David L. Kirp
The New York Times

When it comes to explaining the roots of intelligence, the fight between partisans of the gene and partisans of the environment is ancient and fierce. Each side challenges the other’s intellectual bona fides and political agendas. What is at stake is not just the definition of good science but also the meaning of the just society. The nurture crowd is predisposed to revive the War on Poverty, while the hereditarians typically embrace a Social Darwinist perspective.

A century’s worth of quantitative-genetics literature concludes that a person’s I.Q. is remarkably stable and that about three-quarters of I.Q. differences between individuals are attributable to heredity. This is how I.Q. is widely understood — as being mainly “in the genes” — and that understanding has been used as a rationale for doing nothing about seemingly intractable social problems like the black-white school-achievement gap and the widening income disparity. If nature disposes, the argument goes, there is little to be gained by intervening. In their 1994 best seller, “The Bell Curve,” Richard Herrnstein and Charles Murray relied on this research to argue that the United States is a genetic meritocracy and to urge an end to affirmative action. Since there is no way to significantly boost I.Q., prominent geneticists like Arthur Jensen of Berkeley have contended, compensatory education is a bad bet.

But what if the supposed opposition between heredity and environment is altogether misleading? A new generation of studies shows that genes and environment don’t occupy separate spheres — that much of what is labeled “hereditary” becomes meaningful only in the context of experience. “It doesn’t really matter whether the heritability of I.Q. is this particular figure or that one,” says Sir Michael Rutter of the University of London. “Changing the environment can still make an enormous difference.” If heredity defines the limits of intelligence, the research shows, experience largely determines whether those limits will be reached. And if this is so, the prospects for remedying social inequalities may be better than we thought.

Posted by Laurie Frost at July 31, 2006 7:28 AM
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