Abstract

Human societies are extraordinarily cooperative compared to those of most other animals. In the vast majority of species, individuals live solitary lives, meeting to only to mate and, sometimes, raise their young. In social species, cooperation is limited to relatives and (maybe) small groups of reciprocators. After a brief period of maternal support, individuals acquire virtually all of the food that they eat. There is little division of labor, no trade, and no large scale conflict. Communication is limited to a small repertoire of self-verifying signals. No one cares for the sick, or feeds the hungry or disabled. The strong take from the weak without fear of sanctions by third parties. Amend Hobbes to account for nepotism, and his picture of the state of nature is not so far off for most other animals. In contrast, people in even the simplest human societies regularly cooperate with many unrelated individuals. Human language allows low-cost honest communication of virtually unlimited complexity. The sick are cared for, and sharing leads to substantial flows of food from the middle aged to the young and old. Division of labor and trade are prominent features of every historically known human society, and archaeology indicates that they have a long history. Violent conflict among sizable groups is common. In every human society, social life is regulated by commonly held moral systems that specify the rights and duties of individuals enforced, albeit imperfectly, by third party sanctions.