War in Human Civilization Gat, Azar Oxford University Press, USA (April 15, 2008)
I’m recommending War in Human Civilization, by Azar Gat, because it is - hands down - the best full-scale synthesis of the literature on human warfare, from prehistoric band-level conflict (drawn from ethnographic and archaeological evidence) to modern state-level armed conflict. The book successfully deliniates relevant theories as to the emergence of war and it’s maintenence of economic and social consequences. On the subject of war Gat displays a towering intellect, easily ranging over the relevent literature in anthropology, evolutionary biology, psychology, sociology and political science. If there is a book that tries harder, or gets closer to an answer (or rather, suite of answers) on the question, why war?, I haven’t heard of it.