In both public and professional accounts of the grand sweep of human history, a few questions recurrently beg for attention. How did technology—broadly understood to encompass everything from control of fire to domestication of food sources, to craft manufacture, to communication and transportation—transform human life? How did social complexity come into being: e.g. classes, formal institutions and the state? Why did some ancient societies invest so much effort in corporate constructions such as pyramids, temples and other monumental architecture? What were the effects of warfare and disease on the human condition? And why did the early societies of so many regions cycle between eras of concentrated power and its apparent dissolution?