The Pleistocene Social Contract

No human now gathers for himself or herself the essential resources for life: food, shelter, clothing and the like. Humans are obligate co-operators, and this has been true for tens of thousands of years; probably much longer. In this regard, humans are very unusual. In the living world more generally, cooperation outside the family is rare. Though it can be very profitable, it is also very risky, as cooperation makes an agent vulnerable to incompetence and cheating. This book presents a new picture of the emergence of cooperation in our lineage, developing through four fairly distinct phases. Our trajectory began from a baseline that was probably fairly similar to living great apes, who cooperate, but in fairly minimal ways. As adults, they rarely depend on others when the outcome really matters. This book suggests that cooperation began to be more important for humans through an initial phase of cooperative foraging generating immediate returns from collective action in small mobile bands. This established in our lineage about 1.8 million years ago, perhaps earlier. Over the rest of the Pleistocene, cooperation became more extended in its social scale, with forms of cooperation between bands gradually establishing, and in spatial and temporal scale too, with various forms of reciprocation becoming important. The final phase was the emergence of cooperation in large scale, hierarchical societies in the Holocene, beginning about 12,000 years ago. This picture is nested in a reading of the archaeological and ethnographic record, and twinned to an account of the gradual elaboration of cultural learning in our lineage, making cooperation both more profitable and more stable.