10,000 B.C.

There are increasing returns to scale, set in a general Carneiro-Oppenheimer political equilibrium, albeit with multiple equilibria and possible revolution, depending on the behavior and path of charging woolly mammoths.  Hunter-gatherer societies have martial virtue and also an idea or at least practice of liberty.  They don’t have agriculture or easy transport or efficient risk-sharing or an expensive priestly caste.  The desire for plunder, slaves, and tax revenue causes the wealthier agricultural societies to raid the hunter-gatherers.  The hunter-gathers can adopt the technologies of the wealthier peoples more easily than the overlords can/will adopt the ideologies of the hunter-gatherers.  If the revolt succeeds (see the above remarks about multiple equilibria), the result is both liberty and a higher standard of living.  For unknown reasons, female members of the hunter-gatherer society have market power in the agricultural society, even when they are slaves.

I’m not saying that model is true but I have heard worse from social scientists.