The Science of Good and Evil

Michael Shermer (editor of Skeptic magazine) has recently published a
new book, "The Science of Good and Evil: Why People Cheat, Gossip, Care,
Share, and Follow the Golden Rule"

I think it says more about the nature of morality than all the
theological writings combined. Here is one review on the book:

http://www.nobeliefs.com/Shermer2.htm