Recently I read an article about the Y Chromosome. It suggested that, though small compared to the x, it covers a lot of territory. It also said that it evolves rather rapidly. I haven't a clue what that really means. However, these statements made me wonder about the difference in genetic heritage of the male and female of the species. The male can only inherent his Y chromosome on his paternal line of ancestors, that is from, his father, his paternal grandfather, etc back to some dim distant ancestor. His brother will have the identical ancestry. However some other male will have a different ancestry back to some time where there is a common male parent, some of which will not occur in the ancestral tree until the evolution of speech. As a result of the rapid evolution of the Y chromosome, would it not be possible for males to have evolved to fill different niches within a small scale tribal social group? Is this reasonable?