Getting back to the OP, most of the things described as signs of "evolution" are relatively recent historical developments. Until the advent of agriculture, humans were wanderers by nature, and each gene pool came into contact with others over many generations as competing groups migrated to regions of plentiful food and water. It was probably not uncommon for groups in conflict to take the women of those they defeated. In some groups seizing mates by force could be a rite of manhood for "warrior" cultures. Racial, national or ethnic divisions as we know them did not yet exist; you were either a member of the tribe or you were a stranger. "Races" were differentiated only physically, not socially, because they blended over a spectrum that most human beings alive at the time would never see. Your neighbors or rivals might be slightly lighter or darker than you, or have slightly different faces, but they could bear your children, and that was what counted.

With the advent of the relative luxury of lower infant mortality and greater childbirth survival rates for women, there was no longer an overwhelming need for any and all women a tribe could find. With larger populations, people no longer had to put up with strange-looking outsiders in their midst. They could let their discriminatory instincts and xenophobia have full reign, and separate ethnic groups began to emerge, substituting social isolation for geographic isolation.

Now, we are at another potential evolutionary watershed. A massive population boom, with no natural enemies and a surplus of survival resources, plus worldwide transportation and (in some societies) a relaxing of social taboos against race-mixing. In some cultures, even ones with a high degree of ethnic isolationism, genetic "purity" is not as important as upbringing: I know of an interview with a family in the former Yugoslavia who are raising their son, the child of an affair with a soldier of the "other" side in more peaceful times, to believe his father's ethnic group is the enemy, and that despite his blood he is (whatever the dominant ethnicity of that area is*).

So the idea that specific ethnic/social groups are differentiating is, IMO, premature at best. It ignores history and human nature, and focusses on the actions of a few minorities whose very isolationism is now endangered. While it is possible these exceptions might remain "pure" long enought to lead to true evolution, a long history of milkmen and chambermaids say otherwise.



*I could easily look up the specifics, but they are irrelevant. This same scenario is repeated in areas of ethnic conflict all over the world.

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