The short answer is, ""Not much."" Small (Anthropology/Cornell) is a student of primate behavior, particularly pertaining to mating and parenting. Her take on the subject, while decidedly female, is by no means doctrinaire feminist. The reason? There's so much variation in the social/sexual behavior of primates, nonhuman as well as human, that it would be folly to say that any proposed rationale for coupling was the answer. Instead, we are treated to quite detailed descriptions of the sexual lives of monkeys and apes and us that provide ample examples of polygyny, long-term pair bonding, ""fission-fusion"" behavior in which groups of females and males forage separately and come together to mate from time to time, and other variations. When it comes to human behavior, Small summarizes the most recent findings with regard to anatomy and physiology, obviously pleased to give the lie to the heritage of Victorian prudery: Women are just as likely as men to turn on to erotica and--more to her point--can employ a variety of strategies (besides contraception) to encourage or discourage the potential of a given sex act to lead to pregnancy. She regards seriously the latest evidence that homosexuality may in part be genetic, but she asserts that the larger question is why human sexuality is a continuum, not nice neat packages of this or that. As for fantasies of sex via virtual reality or high-tech sex via surrogate motherhood, she sees them as just that: fantasies or high-tech solutions for the rich and famous. For the rest of us, mating is a complex drive that comes with positive reinforcement. We enjoy it--plus it enables us to pass on our genes. Small is the first to admit she doesn't have all the answers; what she does point out is how much lore we need to unlearn, and that is the beginning of wisdom.