Yeah, and that's before we get to the raping and pillaging behavior we see in modern humans, in which we compete over resources and a (usually more dominant) group literally breeds out their competitors. Sadly, this behavior is not an invention of modern socialization but a rather ancient one found in many species. One would hope it was more tribal/village trade and intermarriage between groups that didn't view themselves as all that different. But, the aforementioned evidence suggests species/race based self-segregation, on the basis of tools, art, graves...likelihood of cannibalism, etc.