I heard an anthropologist say a few weeks ago,that his theory is that what put man over the top,wasn't fire or even the larger brain....it was the fact that man is the ONLY ape capable of making a fist as a weapon. Hmm. I guess early man had some sort of canine teeth and ..flying fists of fury to take on man relatives that existed at the same time. Then,they went extinct.
There's no way to prove that..but sounds like one more edge to the darker side of man that..is just natural.