I really love this Y chromosome tree found here.

Technically there’s just one race because all humans are part of the African clad which is why you often hear the cliche “we’re all Africans under the skin”. Nonetheless, there are three main morphologies corresponding to major evolutionary grades: Negroids (the first four populations pictured), Caucasoids (the next two, splitting off Negroids) and Mongoloids (the last two, splitting off Caucasoids)

One can seen how Rushton would have looked at trees like this and became convinced evolution is progressive. As the tree goes from left to right, the haplogroups become younger (although we could orient it so goes from right to left) and descended from more splits. At the bottom of the tree we have the bushmen who are believed to have absolutely colossal sexual characteristics (consistent with Rushton’s theory that less advanced populations are more r selected).

A better view of the haplogroups is seen here: