TheAlphaWolf: Everybody's mixed, though. There aren't any "purebreed" people on Earth, in terms of race. Are there? Doesn't that tend to confirm that superficial differences don't mirror an underlying genetic truth, then? If you can look black yet have "white mtDNA", are you really black or white, genetically speaking? Or is such as distinction, dare I say it, biologically meaningless? Nevertheless, the degree to which the mtDNA is similar must relate to how far back any two people shared a common female ancestor. More commonalities mean a common ancestor less removed. Therefore, the fact that a person from Tanzania may have more in common with a white American than with a fellow Tanzanian shows that, despite superficial differences in skin colour, the closer "deep" relationship is between the people of different "races". The point of using mtDNA, I thought, was precisely because there is less variance among different individuals. Geneticists therefore find it a useful tool to estimate how long ago two people who shared a common ancestor split from each other. Generally, I think they look at (and count) single base transpositions as a method for establishing relatedness. Yes, provided it doesn't move around. But humans have been moving around more and more, especially over the past 2000 years or so. Yes. All superficial features.