Philip The Wise's Theory of Prejudice

I like this better than my eariler thoughts. This is along the same lines, but much clearer and more robust than the other post.

Racist, prejudiced thinking comes very easy to people all over the world. I would venture to say that most, if not all, cultures around the world have at some point in their history engaged in stereotyping "Them" as generally negative, if not outright evil. A possible evolutionary reason for is that individuals do not evolve, groups and populations do. So, while I have a specific interest in making sure that me and my children survive, I also have a more general interest in making sure my group survives, even if it's at the expense of another group of the same species. In order to make myself OK with the slow (or rapid) extermination of another group of humans, I develop prejudices and hatreds for them. If I am able to see them as something other than human, I'm fine with succeeding at their expense.