Presumably, during long expanses of human existence the biological adaptability of homo sapiens was enhanced by the sexes behaving in distinctly different ways. Differences became encoded in the genes of the two sexes and these genetic differences influenced behavior through the production of kinds and amounts of hormones . Human groups have lived longest in hunting and gathering situations. They point to the existence of sex-specific behaviors in other primates as evidence of their likelihood in humans. They attempt to document the role played by hormones in behavior.
Great variation exists among human societies today with respect to sex specific behaviors.
This variation is difficult to understand biologically. There is significant variation among primates with respect to the degree and kind of sex-specific behaviors present. The relationship between complex behaviors such as caring for young and hormones is difficult to document. For example, we are not yet able to make a mother who is abusing her children into a good mother by injecting her with a mixture of hormones.