Anyone seriously interested in this topic, I'd recommend Richard Rhodes' Why they Kill. A very provocative book, although not necessary gospel truth or the final answer to anything. Coyote Breath makes a lot of sense. Said everything I would have wanted to said. Someone should say that, so I did. I, too, am very suspicious of the "80%" figure for the Civil War. But it was S.L.A. Marshall, a serious scholar, who did the study, and although I don't recall the exact figure, it was amazingly high. Maybe even as high as 20 or 25%.