Evolution

These models [of evolution] do not imply that there are specific sets of genes determining specific social behaviors, but merely that it is unlikely that we would have survived as a species unless we had inherited some structures mediating altruistic behavior, that is some tendencies to help each other under certain circumstances.
		p. 510
Michael Friedman	"Toward a Reconceptualization of Guilt," Contemporary Psychoanalysis 21(4), 1985