People have always been social. Ethnographic evidence suggests that transfers of food and labor are common among contemporary hunter-gatherers, and they probably were common in Paleolithic groups. Archaeological evidence suggests that cooperative breeding went up as we settled down: as territory defenders became more successful breeders, their helpers’ fertility would have been delayed or depressed. And written evidence from the Neolithic suggests that the first civilizations were often eusocial; emperors fathered hundreds of children, who were provided for and protected by (...) workers in sterile castes. Papers in this issue of Human Nature look at helpers and workers across the eusociality continuum—from hardworking grandmothers and grandfathers, to celibate sisters and brothers, to castrated civil servants—from the first foragers to the first states. (shrink)

In Homo sapiens and other species, promiscuity, risk-taking, and aggression are less matters of sex (having XX vs. XY) than gender (giving PI vs. resources and/or genes). Classic role reversals include: sea-horses, polyandrous birds, and a few heiresses in England and Rome. Unlike other females, but like many males, they are assertive, they take chances, and they are not chaste.

Individuals give for two reasons. One is to get a benefit back. The other is to avoid a cost. “Cooperation” theories stress mutual benefits. “Conflict” theories stress costs. Hunters may give up part of their hunt because they get favors back, or because the recipients are stronger than they are and the hunting isn't as good anywhere else.

Why do men and women compete? And what makes them compete more or less? An answer to the first question follows directly from Darwin. If Homo sapiens, like other species, is a product of natural selection, then we should have evolved to compete in order to reproduce. An answer to the second question follows from more recent versions of Darwinism. People, like other organisms, are likely to compete socially - to form dominance hierarchies - to the extent that it is (...) costly for subordinates to flee ecologically. This paper first reviews evidence that winners at political competition have consistently won at reproductive competition. Next, it documents the slow shift toward declining political competition - toward democracy, and toward declining reproductive competition - toward monogamy, in the course of Western history. Last, it offers a model of what might account for that change. (shrink)