Living beings bear with various pressures for survival and such pressures during course of time cause various changes. Even Human beings are not untouched by these pressures. According to a Cornell study which compared genomes of various ethnicities of humans “natural selection has caused as much as 10 percent of the human genome to change in some populations in the last 15,000 to 100,000 years, when people began migrating from Africa.”
The study focused on hot spots on our genome such as skin color which is very different among populations but very similar within a population. Interestingly, the skin pigmentation genes used in this study reaffirms the “Out of Africa” theory long supported by most Anthropologists and Geneticists. While there were changes in skin genes, genes in brain development showed no differences. This was a major and hopefully the ultimate slap to those who still believe Multiregional Hypothesis—that Humans originated in various parts of the world and did not migrate out of Africa (this used to be the basis upon which slavery was implied).
According to Carlos Bustamante, a co-author of the paper, the changes in human genome does not mean that a particular population is more evolved or superior to another rather it indicates how humans have adapted to their newer environment, developed digestion of newer sources of food, and how they have developed resistance to local infectious pathogens.