July 05, 2010

Another lame attempt to wriggle out of the Race/IQ correlation


It's not much of a guess to say that stupid people are not very good at looking after their health and -- though lack of precautions -- may get a lot more disease than smarter people. And when you have got a whole nation of dumb people, the chances of them having good public health measures -- such as providing reticulated sewerage and clean drinking water -- must also be rated as low. So a finding that stupid people get a lot more illness is not remotely surprising.

And that is what the authors of Parasite prevalence and the worldwide distribution of cognitive ability by Eppig, Fincher and Thornhill found. Rather bizarrely, however, they reverse the causal link. They say that poor health causes low IQ! They do end up admitting that they have no proof for their "reversed" chain of causation so their work proves nothing but it is nonetheless amusing to note a few things about their study.

The whole point of the paper is of course to show that Africans have low average IQs not from genetic inheritance but because they are worm infested. And there is no doubt that Africans in Africa do carry a heavy burden of worm infestation -- mainly due to the great lack of public health measures there.

Where it gets amusing is that Eppig et al. did their study in various regions of the world and in 5 out of 6 regions, the correlation held. The exception was South America. The correlation collapsed completely there. Why? Because the South American region included several Caribbean nations almost wholly inhabited by Africans! So why were the results there different from the rest of South America? Could it be a racial difference?

Oh no! Eppig et al say: "It is possible that local parasites ... are causing these outliers". In other words, they abandon the obvious in favour of a totally vague and unfounded speculation!

Two other reasons why the perverse theory of Eppig et al is wrong: They pinpoint nutritional deficit as the mechanism by which parasite load inhibits brain development. But if poor nutition lowers IQ, how do we explain the famous Dutch famine study? In the closing phases of WWII, Nederland experienced a severe famine. So all the Dutch kids born during the famine should be real dummies, right? The reverse happened. They were of higher average IQ than other Dutch cohorts. Only the very healthy survived and, as we have seen, good health and high IQ correlate.

And a second very obvious disproof of the perverse Eppig et al. theory is that black Americans have very similar health environments to white Americans but are still a whole standard deviation lower in average IQ. The Eppig et al theory is, in other words, arrant and transparent nonsense



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