Here is a bit of hard data to respond to the claims that observed performance on IQ tests by those in third world countries reflect genetic deficits. Its a good thing too (even if this was hardly the first piece of evidence on the point) since its easy to imagine that the world could have turned out in a way in which (despite race not being a scientifically useful category) third world populations also suffered from genetic intelligence disadvantages. There is a decent case to be made that the Ashkenazi Jews have genetic differences given them higher average IQs. Notably that case doesn’t merely depend on differences in performance on some tests but, likely all compelling scientific arguments, weaves together an explanation of a number of different phenomena with an appealing theoretical account1. Whether or not this ultimately turns out to be true it could have been true and other undisputed cases of recent evolutionary pressure like adult tolerance for lactose make it abundantly clear that we got very lucky that there aren’t major differences in genetic predisposition to IQ across people of different descent and seeing studies like this reassures me that we really did get lucky and its not just that we are laboring under a desirable fiction.
Even though our racial categories don’t correspond to any principled scientific division at the genetic level it is a classification that correlates with ones ancestry. Given that people still tend to choose mates relatively close to themselves genetically (whether or not race is salient to them or merely geographic proximity) that means it could easily have been the case that, even supposing all developmental and social effects are controlled for, that some races would average much, much worse on IQ tests and other measures of intelligence than others. It wouldn’t really matter that race wasn’t the best scientific category to explain the effect if it turned out that 80% of people we classified as black had genes which cost them 20 IQ points while only 20% of Caucasians and 30% of Semites had this genetic combination. Such a fact would have amplified existing prejudices and resentments making it much more difficult to roll back racist attitudes and laws. In such a world I doubt one of the 20% of blacks without those genes would have had much luck explaining to the white racists around them that no, no, black isn’t the appropriate scientific concept with which to analyze this effect its really this other grouping they should be using, e.g., one which is purely defined via heredity and doesn’t exactly track our racial divisions but just happens to correlate with them.
One might try and argue that there is too much human genetic mixing for substantial genetic differences in IQ to have arisen. While it is true that for the most part humans haven’t partitioned themselves into non-interbreeding (or at least rarely) sub-populations that only holds for the most part and is itself purely a lucky accident. Australian aborigines appear to have been genetically isolated for almost 50,000 years with that isolation only ending quite recently2. There is evidence that the San people in Africa may split off from the rest of the human lineage at around the time modern homo sapiens first arrived on the scene and were then genetically isolated for nearly 100,000 years until only 40,000 years ago. There is no scientific law that ensured there weren’t major genetically isolated branches of the human species with substantially different intellectual abilities which remained separated until the end of the middle ages. It didn’t have to be the case that America was populated by genetically modern humans3 and for less extreme cases one doesn’t even need genetic isolation at all. One can imagine a scenario in which the black death is even worse and attacks the neural system creating strong selective pressure in Europe for a mutation which protects against it despite its detrimental effects on IQ. I suppose one could argue that people are just too rapacious and generally willing to fuck each other for differences to have persisted during the historical era but that is only true if all populations were subject to the same selective pressures and one could certainly imagine a scenario in which only farmers and not hunter gatherers (or vice versa) experience selection for the kind of mixed blessing genes postulated to be more prevalent in the Ashkenazi.
Of course, if we learn enough about genetics and perform sufficiently high powered studies we will probably come across some minor statistical difference in IQ between racial groups. If we assumed that humans were all otherwise genetically identical the small IQ advantage observed in Ashkenazi Jews would be enough to ensure that sufficiently powerful studies would find some average difference. Of course we aren’t all otherwise genetically identical and surely the beneficial and detrimental mutations won’t perfectly cancel out on average. But the fact that we haven’t already found substantial differences and don’t even know who will come out on top if average differences are ever found already means that we got incredibly lucky. It didn’t have to be that the HBD people were wrong, it didn’t even half to be that our racial categories didn’t track scientifically important genetic fault lines. Even though many of the HBD proponents seem so desperately motivated to believe their theories (and not all for racist reasons…some just want to be contrarian) their views certainly describe a way the world could have been and we got quite lucky that human capacities ended up sufficiently close together and interbreeding smeared us out enough that we can’t obviously pick out the more and less capable major ethnic groups.
The Wonder of International Adoption: Adult IQ in Sweden | EconLog | Library of Economics and Liberty
In Selfish Reasons to Have More Kids, I showed that nurture effects are small within the First World. But I also freely conceded that the nurture effects of growing up outside the First World are probably large:The most important weakness…
- In this case the theoretical account suggests that certain mutations which both increase intelligence but also increase susceptibility to certain congenital disorders were selected for in Jews living in medieval Europe and laboring under systematic discrimination which kept them out of most occupations while concentrating them in a few occupations for which IQ was particularly important. ↩
- Though one could, I suppose, argue that had the aboriginal Australians, contrary to fact, been intellectually impaired relative to other humans then relatively nearby populations would have noticed and used their superior intelligence to supplant them. ↩
- For a truly extreme scenario, one could imagine an “out of America” theory of human evolution in which 200,000 years ago proto-humans leave America over the land bridge which subsequently closes (and weather/sea conditions prevent coast hopping) it is only in 1492, after modern humans evolve in the rest of the world, that we rediscover the lost American branch of the human tree. ↩