Sokoloff's post pretty much nails it, but I'll add that it's not just about sex. Before the invention of trade, there was basically no way for one tribe of huma

Sokoloff's post pretty much nails it, but I'll add that it's not just about sex. Before the invention of trade, there was basically no way for one tribe of humans to profitably interact with another tribe. So anyone who has the trait "Treat my genetic relatives (my tribe) nicely; be hostile to anyone who looks different," will have more material success (and more kids) than someone with another set of genes. Give civilization another couple thousand years, and this might change. But if you look at the results of the Implicit Association Test, and the continued popularity of ethnic conflict, you've gotta assume that evolution has a big lead on political correctness. By the way, have you taken the implicit association test? I highly recommend it for those of us who aren't biased. It's often illuminating. https://implicit.harvard.edu/implicit/ https://implicit.harvard.edu/implicit/