HOBBES picks up an ancient thread: “It is true that certain living creatures such as bees and ants, live sociably with one another (… by Aristotle numbered amongst political creatures), … and therefore some man may perhaps desire to know why mankind may not do the same.” In our own time the question arises in greater variety and detail. The problem of the social contract has been solved in many different ways at all levels of biological organization. To the ants and the bees we can add social amoebas, such as the cellular slime molds, and even social bacteria like the “wolf-pack” Myxococcus xanthus. Inside a human body, there is the society of organs — well known to the Greeks — composed of societies of tissues, which are in turn composed of societies of cells. The social contract for the body of a multicellular organism is written again and again in chromosomes in each cell. Chromosomes are societies of genes. Each cell also has a subsidiary contract with its mitochondria, formalized in their DNA as well as its own. It is evident that rational choice is not necessary for solving the problem of the social contract.

Hobbes thought that rationality was part of the problem. Ants and bees act together by instinct, not reason: “The agreement of these creatures is natural; but that of men is by covenant only, which is artificial.” Humans are tempted to defect by rational self-interest.