IQ: Here we go again

[There has been a] small rush of articles that have been sparked by James Watson's perfectly factual observations about black IQ. The New Yorker's contribution appears under the heading "None of the above" and is by Malcolm Gladwell, a historian who takes an interest in the social sciences. Gladwell is of course among the "saints" who think IQ is all nonsense.

All Gladwell does, basically, is rehash the usual points made by Flynn -- so any critique of Flynn (e.g. here) should be an adequate reply to Gladwell. I will however mention a few points here. Another point Gladwell raises is that the black/white gap rises from a small gap in infancy to a much larger gap in later life. Gladwell thinks that shows an effect of black culture but the real explanation is again rather blunt so I will simply refer readers to an extended comment I made on that matter recently.

But Gladwell's basic blindness is to fail to distinguish between phenotypic IQ (scores on IQ tests) and genotypic IQ (that part of IQ test scores which is genetically determined). Nobody has ever denied that IQ test scores are influenced by environmental factors -- about a third of IQ is usually found to be environmentally determined -- so the rise in the IQ scores of most populations over the 20th century (as described by Flynn) was to be expected from all the many advantages that modernization brings -- better nutrition, greater stimulation via TV, more time in the educational system, better perinatal medical care etc. But if genetics set a limit, the improvement to IQ scores that flow from an improved environment should peak as the environment reaches the optimum for IQ development. And precisely that has now happened in several affluent countries.

So Flynn's findings don't let you escape those pesky genes! It is in fact rather amusing to hear an attack on genetic influences in this day and age. We now hear almost daily (in the medical and psychological literature) of new findings about genetic influences on human behaviour -- so much so that it would be amazing if there was NOT a large genetic influence on IQ.