Just finished reading the new book by Steven Pinker called The Better Angels of Our Nature: Why Violence Has Declined. The book argues that, contrary to popular opinion, violence has declined in virtually every category we can think of since civilization began (albeit unevenly across time and geography, and with a few blips along the way). the book also explores the forces in human nature that incline us towards violence and those that incline us away from it. I've written a full executive summary of the book available here: http://newbooksinbrief.com/2012/01/28...
Cheers,
Aaron