Economists and biology

Naturally, economists know a lot about human biology and evolution, just as civil engineers have to know about the properties of timber, concrete and steel. They have a good grounding in psychometrics, behavioral genetics, and quantitative genetics – how else could they do their job? Populations vary in traits that play key roles in economic activity and growth – in intelligence, asabiya, savings propensity, etc – you have to be aware of that variation, else whole continents would be economic mysteries. In the same way they know that those observed differences are a product of selection – which means economic historians think seriously about psychometric changes over time and their consequences, such as the Industrial Revolution. That kind of analysis helps predict where modern economic institutions can be successfully introduced, and where they cannot.

Yet even Jove nods. Sometimes even tenured professors make serious errors on fairly elementary topics. Like anyone else who has made a mental typo, they welcome polite correction.

Deirdre McCloskey has a new book out: Bourgeois Equality: How Ideas, Not Capital or Institutions, Enriched the World. I’m sure that there are many good things in it. But McCloskey makes a significant error in talking about genetics. “Know also a remarkable likelihood in our future. Begin with the sober scientific fact that sub-Saharan Africa has great genetic diversity, at any rate by the standard of the narrow genetic endowment of the ancestors of the rest of us, the small part of of the race of Homo sapiens that left Mother Africa in dribs and drabs after about 70,000 BCE…. Any gene-influenced activity is therefore going to have more African extremes. The naturally tallest people and the naturally shortest people, for example, are in sub-Saharan Africa. The naturally quickest long-distance runners are in East Africa. The best basketball players descend from West Africans. In other words, below the Sahara the top end of the distribution of human abilities – physical and intellectual and artistic – is unusually thick. …

The upshot? Genetic diversity in a rich Africa will yield a crop of geniuses unprecedented in world history. In a century or so the leading scientists and artists in the world will be black – at any rate if the diversity is as large in gene expression and social relevance as it is in, say, height or running ability. ”

So by this argument that the most cold-tolerant Africans must be more cold-tolerant than Eskimos: but they’re not. The most altitude-tolerant Africans must be more altitude-tolerant than Tibetans – but they’re not. McCloskey is thinking that a turn to free markets will make Africa rich, and that will give educational opportunities to Africans now denied them – but a fair-sized mostly-African population already lives in the United States, a population that is already much more prosperous than sub-Saharan Africans. How are they doing? How many geniuses are they producing?

The whole argument is flawed. Overall genetic variation is mostly in neutral loci. By itself it tells you nothing about any particular trait. Europeans do have less overall genetic variation than sub-Saharan Africans (~20% less), but they show more variation in hair color and eye color than Africans.

Essentially every domesticated species has less genetic variation than its wild progenitor. Dogs have less genetic variation than wolves. So, does this mean that the tallest wolf is taller than any dog? No – the tallest Great Danes are taller than any wolf. The heaviest mastiffs are heavier than any wolf. Chihuahua are the smallest. Greyhounds are faster than wolves (by a little).

Thoroughbred horses have little genetic variation – their effective population size is under 100. Tarpans, the wild ancestor of domesticated horses, are extinct, but there certainly are horse breeds with much more genetic variation than Thoroughbreds. But they’re slower.

What matters is the frequency of alleles that influence a trait, not overall genetic diversity. If, for example, the variants that tend to boost educational achievement (some of which were found in the just-released Nature study) were on average less common in sub-Saharan Africans than in Europeans – says 5% less common – Africans would tend to do less well in school. Like they actually do. Now Africa is a big place, and some groups are genetically quite distinct from others. Bushmen are genetically more distant from the Bantu than the Bantu are from Chinese. Some African populations might have experienced selective pressures that were more (or less) favorable for intelligence than others. Is there evidence, either in test scores or cultural accomplishment (better than any test), that some African populations may have smarts comparable with, or better than, people in Switzerland or Holland or Scotland?

No. There is no such evidence.

How many real geniuses out of African populations – people like Fermat, or Riemann, or Gauss, or Laplace? Newton? Maxwell? Gibbs? None. How many of the top 1000 mathematicians in the 20th century were of sub-Saharan ancestry? One, perhaps?

McCloskey’s prediction of an efflorescence of African genius is based on an incorrect understanding of how quantitative traits work. It’s also in that interesting, ever-popular class of theories that are contradicted by everything that has ever happened in the history of the world.