A recent study found that societies “flourish when their populations have just enough genetic diversity, but not too much”:
Of the 145 nations considered in the 2000 comparison, Bolivia, one of the world’s poorer countries, was the most genetically homogenous. The authors calculated that if Bolivia’s level of genetic diversity were just one percentage point higher, its current per capita income would be 41 percent greater.
Ethiopia, where the first modern humans emerged 150,000 years ago, lies at the other end of the spectrum. There, extreme genetic diversity has led to crippling poverty. A drop in heterozygosity of just one percentage point would result in a 21 percent bump in contemporary income per capita, the authors found. … The nation that came closest to the ideal level of post-industrial genetic diversity? According to Ashraf and Galor’s calculations, it was the United States.