John Horgan is no wild-eyed optimistic. True, his belief that the end of war is imminent was based on a moral conviction. But Horgan also points to a body of empirical evidence from scientific investigations of warfare. He writes in a new book called The End of War: Evidence of lethal group violence dates back not to the emergence of the Homo genus millions of years ago, nor to the emergence of our species hundreds of thousands of years ago, but to less than thirteen thousand years ago, shortly before the dawn of civilization. In other words, war is a cultural, not a biological phenomenon.