Quamrul Ashraf and Oded Galor have found (pdf) a humplike correlation between the genetic diversity of populations and their levels of economic development.
They measure genetic diversity by the distance from out-of-Africa human migration: population bottlenecks mean that genetic diversity is high in East Africa, medium in Eurasia, and low in the Americas. (All this is before more recent migrations.) High and low diversity (Africa, Americas) is associated with less development than the medium or Goldilocks just-right level (Eurasia).
What’s the mechanism?
I don’t know and nor do the authors. But they do make a tentative suggestion:
The benefits of genetic diversity … in the Darwinian theory of evolution by natural selection … increases the adaptability and, hence, the survivability of a population to changing environmental conditions.
Well, yes, variation is needed for selection. But its a very, very long way from there to economic development.
On the other hand, to the extent that genetic diversity is associated with a lower average degree of relatedness amongst individuals in a population, kin selection theory, which emphasizes that cooperation amongst genetically related individuals can indeed be collectively beneficial as it ultimately facilitates the propagation of shared genes to the next generation, is suggestive of the hypothesized mechanism through which diversity confers costs on aggregate productivity.
Also, an intriguing idea, that homogeneity increases cooperation which aids development. But it also seems to be a long way from really nailing down what the mechanism may be.
Quamrul Ashraf and Oded Galor, “The Out of Africa Hypothesis, Human Genetic Diversity, and Comparative Economic Development” American Economic Review forthcoming.