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Catfish and Cod
Tuesday, September 02, 2003
Nature vs. nurture: IQ.
(Link path: The Volokh Conspiracy, Washington Post, Psychological Science 14(6) (in press))

A new report says that environmental factors determine IQ among the poor, while genetics controls IQ among the rich. This finding suggests that, for an individual to reach his or her full potential, there is a required level of the environmental factors generally referred to as "nurture".

It also suggests that not everyone is receiving that level of nurture.

The findings suggest that different strategies may be called for in preparing students of differing SES (socio-economic status). For instance, additional nurture is not helpful for purposes of raising IQ in wealthy households. If the child takes to additional educational stimuli, all well and good; but if the child isn't responding, compounding efforts will not help. On the flip side, there is a serious deficiency among lower-income households that is holding back poor students. The next obvious question: what deficiency is that?

The Post, being a good Democratic paper, says that means Great Society-style programs are worthwhile:

The results suggest that early childhood assistance programs such as Head Start can help the poor and are worthy of public support.

It doesn't suggest anything of the sort. It merely suggests that there is something wrong with the environment that poor children are raised in. (Not too terribly surprising.) But it doesn't suggest what is wrong with that environment. It might be something Head Start isn't touching, like parental tutoring or appropriate discipline. Who knows? No one -- the study only used SES as a variable, not any specific aspect of family life.

Journalists may not understand this, but other scientists do.

Marcus Feldman, a population geneticist at Stanford University who has studied gene-environment interactions, said the next big challenge is to find out what it is about socioeconomic status -- a measure that includes not only income but also parental education and occupational status -- that contributes to IQ, so social programs can more effectively boost those factors.

"SES is a surrogate for something that deserves further study," Feldman said. "A paper like this reemphasizes the importance of psychology and educational psychology and draws us somewhat away from genetics and back into the importance of the social sciences for understanding IQ. This says to me, let's spend the money and find out what it is about SES that makes the difference."

Don't get me wrong, we should study genetic factors too. But this study shows that works like The Bell Curve were built on biased evidence (collected solely from middle-class and wealthy families). Always be sure your data is reliable before drawing too many conclusions...