Long ago, historians more or less gave up on "theories of history." They determined that human nature was too unpredictable, cultures too various, and developmental patterns too evanescent for any really scientific theory of history to be possible. Human history, they said, was chaos.
The problem is that human history isn't chaos at all. The "hard" human sciences–evolutionary biology and anthropology in particular–have shown that human nature is quite predictable, cultural variability is strictly constrained, and ongoing patterns of social development have ancient roots. Historians can ignore these facts all they like, but that doesn't make them any the less true. It does, however, impoverish their discipline by ceding the search for a satisfying theory of history to scientists. Neither Paul Bingham nor Joanne Souza are historians. The former is a molecular biologist and the latter an evolutionary psychologist. But they have formulated an elegant theory of human history in Death From a Distance and the Birth of a Humane Universe (2009). Like any good theory, it explains a lot with a little. To put it briefly, human society has gone from simple/small to massive/complex because humans alone among animals were/are able to suppress intra-group conflicts of interest by means of low-cost coercion. Bingham and Souza point out that the big "jumps" in social size and complexity–the neolithic revolution, the growth of archaic states, the birth of the nation-state, the rise of globalization–have all been associated with the evolution/introduction of new, more powerful coercive abilities. Paradoxically, it was new weapons that created more and better lives over the course of the last several hundred thousand years.
This brief summary cannot do justice to the richness of Bingham's and Souza's theory. You need to read it for yourself. When you do, I guarantee you will see the past and present in a new way.
Please become a fan of "New Books in History" on Facebook if you haven't already.