I just completed my first reading of Ultrasociety: How 10,000 years of war made humans the greatest cooperators on earth. It needs a few more readings. I cannot say that I understood all parts of the book and felt that several parts were locally not quite correct, at least they seem to be against what I learnt from Michael Hudson and others. On the otherhand, that does not seem to matter. It is a theory capable of incorporating change of details and some predictions. It seems worth reading and pondering about. An earlier paper War, space and evolution of old world complex societies by Peter Turchin and colloborators will provide a preview of some of the ideas. Worth a look.