How much is explained by IQ? I suppose making arguments about the importance of IQ in explanations of economic growth, longevity and so on is about as controversial as research gets. Anyone brave enough to tread into this minefield is sure to be hit from all sides. Bryan Caplan is of the opinion that IQ matters for all kinds of things and that to ignore it in, say, a model of the effect of education on earnings will mean overestimating the effect of schooling.
Thus, IQ is highly policy-relevant after all. The left-wing ideologues who damn anyone who even thinks the letters “IQ” are actually on to something: IQ research does turn out to be a rationale for “right-wing” laissez-faire policies. The more IQ matters, the more likely it becomes that existing government policies are a waste of money – and that you would get a bigger payoff by doing less – or maybe nothing at all.
This is controversial enough for many people. Now add race (implicitly, if not explicitly) to the mix. Speaking of mix, another one who has partaken of the mixed grill, Satoshi Kanazawa, has a paper in the current issue of the British Journal of Health Psychology that is sure to stir the pot. Here’s the abstract:
Wilkinson contends that economic inequality reduces the health and life expectancy of the whole population but his argument does not make sense within its own evolutionary framework. Recent evolutionary psychological theory suggests that the human brain, adapted to the ancestral environment, has difficulty comprehending and dealing with entities and situations that did not exist in the ancestral environment and that general intelligence evolved as a domain-specific adaptation to solve evolutionarily novel problems. Since most dangers to health in the contemporary society are evolutionarily novel, it follows that more intelligent individuals are better able to recognize and deal with such dangers and live longer. Consistent with the theory, the macro-level analyses show that income inequality and economic development have no effect on life expectancy at birth, infant mortality and age-specific mortality net of average intelligence quotient (IQ) in 126 countries. They also show that an average IQ has a very large and significant effect on population health but not in the evolutionarily familiar sub-Saharan Africa. At the micro level, the General Social Survey data show that, while both income and intelligence have independent positive effects on self-reported health, intelligence has a stronger effect than income. The data collectively suggest that individuals in wealthier and more egalitarian societies live longer and stay healthier, not because they are wealthier or more egalitarian but because they are more intelligent.
I haven’t read the paper so I can’t really comment on the data or analysis. No one can accuse him of studying boring stuff though.