Considering that our culture invented napalm and nuclear weapons, I'm not sure we're in a position to judge the smaller scale violence of other cultures. But it's important to note that none of the cannibal or headhunting groups were true hunter-gatherers. They had already begun to use agriculture. It is now generally conceded that agriculture usually leads ot a rise in labor, a decrease in sharing, an increase in violence, and a shorter life expectancy. This is not to say that all agricultural societies are violent, but rather that violence is by and large not characteristic of true hunter-gatherers.

Running on Emptiness: The Pathology of Civilization (2002)