You seem to have a pretty serious misunderstanding of human nature. While nature in general may be "red of tooth and claw", our species' claim to fame is an elaborate social structure that facilitates cooperation and sharing. The nature of the human tribe is that it is obligated to share resources among its members...or it loses its legitimacy under primate rules. The reality for humans is the opposite of "The group mentality will not allow the sharing of resources with others". The group mentality requires it.

Now if you're talking about intertribal competition and hostility, the interesting thing is that it arises from a human perception that's amenable to change: The perception of the scope of the tribe of which you're a member.

Human history so far has been characterized by a general growth in that ability. Most people can now perceive their tribe as being much larger than the baseline couple of dozen primates dictated by the basic mental wiring. Among Americans, the majority seems to be at the boundary between regional and national loyalties (you unreconstructed Conferederates come to mind), with a not-inconsiderable number genuinely able to perceive America as a whole as the real tribe. Interesting, too, is that tribes don't have to be determined by geography, and a great many Americans seem more loyal to their political party than to the nation as a whole. I'm not talking disloyalty, but rather the phenomenon by which the like-minded members of one's own political tribe seem to be closer kin than the "foreigners" in another political tribe; and the concept of a national tribe seems more abstract than the kinship within a political party.

I'm not interested in preaching peace and brotherhood. I'm interested in leveraging and growing the "natural instincts bred into us over a billion years of evolution" (well, to be precise, in our case, a million years of hominid evolution) to tap into the natural loyalty and obligation to a larger tribe...humanity as a whole. People aren't naturally predators towards other people, the problem is just that they have trouble recognizing different humans as humans.

If ever there was a poster child for stunted social evolution, it would be you, Lee. You've made it abundantly clear that you have trouble recognizing even your fellow Americans as human, if their skin color or culture deviates even a little bit from your own. You're at the trailing edge of the Bell curve of human social evolution, and it's the existence of people at the opposite extreme of that curve that keeps me optimistic.