Re: Hormonal & Psychological Responses to Combat
Warfare in hunting and gathering or early agricultural society generally involves raiding rather than invading, and killing often -- but not always -- may be relatively infrequent or unnecessary. For example, counting coup among the Plains Indians, or the highly ritualized raiding in the New Guinea highlands.
In this context, human aggression seems on a continuum with conspecific aggression by other primates such as chimps.
At the same time, the anthropological record contains examples of what we would view as mass murder, for example, among the Inuit.
I think the idea that human beings are reluctant to kill other human beings makes evolutionary as well as sociological sense for highly social animals. Still, clever monkeys that we are, human societies sculpt and organize the human capacity for violence in myriad ways.
But I don't have statistics to prove that hypothesis.