I found a first look at the problem with a reference to the book On Killing by David Grossman, a former military officer (Little, Brown, 1995). Grossman turns out to be a recognized expert in this field of study and is especially critical of many video games as sources of violent acts by children. Here is an interesting article by Grossman on the subject of violence.

Grossman's thesis is that humans posess a natural reluctance to kill members of their own species unless they've been psycologically conditioned to kill. If he is correct then my notions of violence as a genetically inherited response are probably out the window.

I'll try to find more on this subject from other sources.

      - Mark