It's interesting - I read somewhere that about 70% of Caucasians can digest milk, but about 70% of African-Americans cannot. Interesting generalisation. Has anyone told the Masai?
Due to evolution (or IntDes), ability to digest lactose is associated with the traditional cattle raising regions: Europe, the Mid-east, the Indian sub-continent, East Africa.
But not the Orient, west Africa, and the Americas.
It seems that my ancestors co-developed with cattle. I enjoy drinking more than a quart a day of raw whole milk from cows feeding themselves on green pasture.
(I've northern European roots rather than Masai--those tall extra healthy Africans that not only drink their cattle's milk, but their blood as well. I'll stick to just the milk.)