Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past

by David Reich

The indefensibility of the orthodoxy is obvious at almost every turn. In 2016, I attended a lecture on race and genetics by the biologist Joseph L. Graves Jr. at the Peabody Museum of Archaeology and Ethnography at Harvard. At one point, Graves compared the approximately five mutations known to have large effects on skin pigmentation and that are obviously different in frequency across populations to the more than ten thousand genes known to be active in human brains. He argued that in contrast to pigmentation genes, the patterns at genes particularly active in the brain would surely average out over so many locations, with some mutations nudging cognitive and behavioral traits in one direction and some pushing in the other direction. But this argument doesn’t work, because in fact, if natural selection has exerted different pressures on two populations since they separated, traits influenced by many mutations are just as capable of achieving large average differences across populations as traits influenced by few mutations. And indeed, it is already known that traits shaped by many mutations (as is probably the case for behavior and cognition) are at least as important targets of natural selection as traits like skin color that are driven by a small number of mutations.

Naturl selection is nit the iaaue