Almost all living humans live in social world that are profoundly unequal in wealth and influence. By the standard of deep human history, that is a recent change. For most of our history humans lived in egalitarian, acephalous communities. This paper focusses on two questions. First: how and why did the social world of egalitarian foragers transition to the unequal worlds of early farming societies and other unequal farming communities. What caused the failure of the mechanisms that guarded equality in egalitarian worlds? Second: why did cooperation, collective action and, in general, the social contract persist through that transition? One of the robust results of both theoretical models and behavioural economics is that cooperation falls apart when free-riding is not controlled. Elites are free-riders, and yet the non-elite continue to contribute, not everywhere but often, to collective action. Theory and experiment seem to be in conflict with much of the last ten thousand years of human history. I’ll suggest answers to these questions based on individual optimising decisions, rather than ones that depend on various versions of cultural group selection.