> why did this kind of behavior evolve? It's just an extension of the competitive nature of humans/social animals. Social animals despise animals of the same s

> why did this kind of behavior evolve? It's just an extension of the competitive nature of humans/social animals. Social animals despise animals of the same species that are of different social groups. They all want their social group to prevail, and will attack (actively or passively, e.g. by refusing culture) the others. Humans like to think they are above this 'primitive' instinct, but I think the vast majority of human behavior can be summed up by this.