Does natural selection appear to have played a role in the evolution of lactose tolerance in humans?
Yes, natural selection has played a role in the evolution of lactose tolerance in humans. I remember reading a paper about this some time ago, so my memory might be a bit fuzzy. But here’s the gist: The people of Africa didn’t drink milk as adults until relatively recently. In areas where Africans raised animals and drank their milk, the individuals who could “tolerate” the milk as adults gained significant advantage over the people who could NOT (eg they had diarrhea or something) because, as you know, food is hard to come by in many parts of Africa. So milk would be a very valuable food resource, if one can tolerate it. As predicted, in areas of Africa where people drank milk, the number of people with lactose-tolerant genes was significantly higher than people without lactose-tolerant genes. Natural selection increased the number of lactose-tolerant people.
