As Aristotle noted long ago, we are, by nature, social animals. Human evolution has increased the importance of social knowledge and social context. Prosocial behavior underlies the moral sensibility that pervades human experience resulting in significant human contact.
Darwin emphasized a fundamental prosocial feature of us, essential for moral judgment. He asserted, “… any animal whatever, endowed with a well-marked social instinct, the parental and filial affections being here included would inevitably acquire a moral sense of conscience, as soon as its intellectual power had become as well or nearly as well developed as in man” (1874: 95). However, in Descent of Man, Darwin also noted the “the fewness and the comparative simplicity of the instincts in the higher animals are remarkable in contrast with those of the lower animals” (1874: 65).
Adapting to the social milieu is a fundamental feature of our species. Darwin, like others before and since, understood that we are social animals. What has emerged in Homo sapiens has been an elaboration of social contact, the expansion of individual responsibility manifested in specific types of the division of labor in the service of group safety and human well-being and productivity. There has also been a technical expansion resulting in the development of a diverse supply of cognitive resources, including cognitive resources which pitted, at times, deception against social cooperation as conflicting motivations (Dunbar and Shultz, 2007).