Humans had to evolve what no other primate had: a sense of identity with a group so powerful that it could swallow up the individual identity, at least to a large degree. Humans couldn't have the deep, self-sacrificing loyalty to more than one or two communities at a time. Thus communities were inevitably in conflict with each other, competing for the loyalty of their members. The tribe had to break down the solidarity of the family; religion had to compete with nation for loyalty. But once a community had that loyalty, the most ardent members would gladly die for it. Not for the other individuals directly, but for the interests of the group as a whole, because in the human mind, that group was the self, and the individual was able to regard himself as merely one iteration of the pattern of the whole

Identity·War·Loyalty·Evolution