Rapid Change in Polygenic Traits

they’re not terrible well adapted to their new mental horsepower. Susceptible to various mental problems and illusions that would probably be a lot rarer if natural selection had had time to iron out the bugs.

West Hunter

A few people have occasionally claimed that natural selection takes a long time to change any trait that might bother them – sometimes, they say this of polygenic traits, ones influenced by many genes, like height and intelligence. Kevin Mitchell has said this (“at least 100 millennia to evolve appreciably”), so has Brad Delong (an economist at Berkeley). David Reich mentions Joseph Graves, in a talk at Harvard, saying something similar in a lecture in 2016. They’re all 100% wrong: it is easy to select on polygenic quantitative traits, and we do it every day. Dogs vary a lot in height and most of the big differences are the result of fairly recent selection: nobody had Chihuahuas or Great Danes back in the Ice Age.

Human populations vary in height – not just from differences in nutrition. We know [work from the Reich lab] that northern Europeans are around a…

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