https://quillette.com/2019/01/25/how-real-is-systemic
John Staddon is a James B. Duke Professor of Psychology and Professor of Biology, Emeritus, at Duke University.
Racist attitudes of whites towards blacks have long become socially unacceptable in America, although the reverse, racism of a minority directed at the white majority, is still tolerated or even encouraged. However, statistical racial disparities persist. African Americans, as a population, continue to suffer income, crime and incarceration rate, health, housing and family-structure deficits by comparison with the white population.
These disparities cannot easily be attributed to racist behavior by whites. The disparities have either increased or remained the same while individual racist behavior has declined. What then is the cause of these disparities? There are two possibilities: causes within individuals, what I have elsewhere called endogenous causes; or external, exogenous causes.
Endogenous Causes of Black-White Disparities
Endogenous causes were in fact the first ones to be studied, with unfortunate results. Bigots stigmatized the entire “black race” as inferior because of lower average scores on, for example, IQ tests. Blacks’ under-performance in terms of status, health, incomes, etc. was then comfortably attributed to their alleged built-in inadequacy.
The usual presumption was that IQ is fixed at birth, that it is the most important factor in life success and that it cannot be altered by later experience. None of these is true; although the fixity-of-IQ view seemed to be supported by several studies showing relatively high (statistical) heritability for IQ. But heritable is not the same as fixed: high statistical heritability for a behavioral trait does not imply that it is fixed at birth and independent of the rearing environment. Language is the most obvious counter-example. It is a learned behavior that also has high heritability. Language is 100 percent learned and 100 percent heritable—kids learn the language of their parents.
The only reason we know that language is not a sort of instinct is the “natural experiments” provided by adoption. Despite the high heritability of language, adopted infants learn the language of their adoptive, not biological, parents. It follows that high heritability does not mean genetic determinism. Statistical heritability depends on rearing environment as well as genetics.
What kind of experiment would be needed to prove that intelligence, which is also (statistically) heritable, is in fact genetically determined? What would it take to show that there are irreducible average-IQ differences between races: that no matter how rich the environment, blacks and whites would still have differing average IQ, leaving genes as the only cause? Only a very elaborate, unethical, and in practice un-doable, experiment could do it.
