Violence between groups exist in other animals as well. My take is that this is a natural consequence of competition for resources. The more individuals or gro

Violence between groups exist in other animals as well. My take is that this is a natural consequence of competition for resources. The more individuals or groups are organised, the more violence becomes organised as a logical consequence. We have evolved as social animals members of tight groups and this seems to be quite old looking at chimpanzees and gorillas, for example. So this 'tribal' streak is probably embedded in us to this day.