Cooperation, Stability, and Scale
There is reason to suspect that [the transition from the relatively closed social world of a great ape residential group to the richly connected forager bands of ethnography ] was very gradual. Its initial roots may date back to the Heidelbergensians, at about 800 kya. But it was not complete until the very late Pleistocene (perhaps even later). For it is only then that we find evidence of active cooperation across residential groups, and perhaps of clan structures that transcend an individual forager band. The final transition began in the terminal Pleistocene (about 25 kya–12 kya) and in the early Holocene, with the origins of sedentary society. This led to an increase in social scale and social inequality. In trying to understand why cooperation is stable, scale, complexity and inequality all matter. For mechanisms that suffice to stabilize cooperation in small politically unstructured and relatively homogenous social environments breakdown in larger and more structured ones. Personal knowledge and trust can stabilize cooperation in small, intimate social environments but not larger and more differentiated ones. Continued cooperation is especially puzzling in social worlds that are not just larger but also hierarchically structured. For these seem to be cases where the profits of cooperation are largely hijacked by elites. In such cases, theory predicts the collapse of cooperation. The take-home message of this chapter is that culturally evolved tools—language, myth, ritual, explicit norms—play a central role in the stability of cooperation in the late Pleistocene shift in the economic foundations of cooperation, and an equally central role in the survival of the social contract through the final Pleistocene and early Holocene social revolutions.
Kim Sterelny, The Pleistocene Social Contract, p. 58