OK, but that was a quarter billion years ago, give or take a few thousand millennia. What we care about is what might happen nowadays, what with that so-called climate change or nuclear winter or whatever disaster the liberals have their panties in a twist about.
Turns out that our human nature has a lot to do with how all this might shake out. And there has been no shortage of certified smart people telling us what human nature is for a long while. Professional philosophers still tell us in learned books and did so all the way back to Socrates and his predecessors. One of the founders of the discipline of sociology noted well:
In the eighteenth century it was assumed that the primitive state of mankind was one of Arcadian peace, joy, and contentment. In the nineteenth century the assumption went over to the other extreme--that the primitive state was one of universal warfare.
--William Graham Sumner, 1911 (in Barash, 2013)
So you might consider the Rousseauian optimism of all of us as potential 'noble savages' romping in our bucolic frolic through the fields of flowers. Or you can remove your Rousseau-colored glasses and plummet into the bloodbath of Hobbesian perspective of human life as 'nasty, brutish, and short' (self-description?). Neither handles conflict well, do they?
And how we choose to handle conflict as a collective--whether our decisions will produce a sociology of conflict transformers or a society of equally doomed Pollyannas or Mad Bombers--is how we determine our chances for species survival in the face of emerging and growing threats.
Anthropologists have disproven Thomas Hobbes and his notion of life as a war of all against all; there are many societies that do not practice war. War itself shows that Rousseau only had a vision, not a claim on real human nature. In fact, there are greedy ones, there are evil ones, there are brutal ones, there are sociopathological ones. However, in fact, history teaches us that there are nonviolent ways to overthrow those poor leaders, those violent ones.
Who are we? We are Homo creativus, the only species that is hard-wired for creativity, and that is what we access when we act nonviolently. Nonviolence requires the only existential response that no other species is significantly hard-wired to achieve. It is creative assertion--sitting down where you are supposed to stand or move if you are not of a certain skin color, or putting a flower into a gun barrel that is pointed at you.
Barash, David P. (Ed.) (2013). Approaches to peace: A reader in Peace Studies (3rd ed.). New York: Oxford University Press.