An article on why people monitor their neighbors' sexual behavior and apply social pressure to punish those who break the rules:Other People's Sex Lives
Evolutionary psychology, according to this article, speculates that condemnation of casual sex is ultimately a matter of economics. A study in THE ARCHIVES OF SEXUAL BEHAVIOR "found that promiscuity—by both men and women—is more likely to be considered a moral violation in places where women are economically dependent on men." Men don't want to be tricked into supporting children they didn't father. Women don't want their husbands diverting resources to other women (and their children). Women, according to this research, are more inclined than men to "shame" other women who engage in casual sex, because someone who "gives it away" (to use an old-fashioned term) is spoiling the field for women who play by the rules. Now that contraception has separated sex from reproduction and most women in our society don't depend on male support for survival, condemnation of casual sex should fade away. However, attitudes that have become hard-wired through evolution—assuming this behavior really has evolved that way—lag behind changes in culture.
This perspective on sexual relations goes back a long time. Samuel Johnson, for instance, declared that an unfaithful husband does no serious harm to his wife because a man who commits adultery doesn't foist bastards on his wife. I would rather see marital fidelity as rooted more in equally shared love and intimacy than in economics!
The article concludes that "judging other people’s sex lives remains an act as innately human as sex itself," making the economically-based demand for fidelity sound universal. In fact, though, it's culture-bound. In some pre-industrial societies, for instance, a woman's acceptance of multiple sexual partners works in her favor where support is concerned. A pregnant woman shares sex with as many men as possible, because every man she couples with thereby becomes a "father" to the infant. Children can have several fathers, all of whom contribute to their maintenance.
Women's economic dependence on men has no relevance to sex in matrilineal cultures, where the child belongs to the mother's clan, and she stays with her family of origin rather than living with her mate. The biological father doesn't play the role of family headship and financial support traditional in our society. The children's uncle—the mother's oldest brother—fills that position.
No connection at all among sex, proof of paternity, and financial support would exist among the logical Vulcans. Reproductive sex can happen only during pon farr, and that can occur only between bonded mates. So sexual straying, even if possible (T'Pring's plan for her future with Stonn hints that it is), could not result in offspring to cloud issues of inheritance. And of course the whole concept would be totally irrelevant to a species such as the one in Le Guin's LEFT HAND OF DARKNESS, humanoids who remain sexually neuter except for a brief period each month and become male or female, potentially father or mother, at random.
Margaret L. CarterCarter's Crypt