I recently came across Hooking Up Smart, a blog aimed at young women that tries to explain the practical realities of the market for sex. These are both simple and interesting:
The commodities that trade on human sexual markets are Commitment, Sex, and Attractiveness. The first two commodities are behavioral, so their supply can fluctuate with social norms, whereas Attractiveness is mostly fixed and out of the control of each market participant. (Both genders have evolved Attraction to gene-linked “beauty” characteristics of the opposite sex, many of which are immutable, that contribute to the survival and success of offspring. What men experience as sexual Attraction is generally a combination of a woman’s “beauty” and apparent fertility. What women experience as Attraction is generally a combination of male “beauty” together with a man’s power, wealth, or social status. In each case the most Attractive market participants enjoy above-average sexual capital and are referred to as “alphas.”)
Men make the market for Commitment: A male’s optimal reproductive strategy is to inseminate any woman who might bear children, but only to support women with children who are (likely to be) his own. Given the chance, a man will try to “lock up” the most Attractive women he can, at least while they are fertile; sex with more promiscuous or less fertile women is a lower-cost but less reliable means of reproduction.
Women set the market price for Sex: They have relatively few shots at reproduction, and they disproportionately bear its costs. The primal female mind balances the value of a prospective mate’s genes to her offspring with the fact that his long-term support might more than overcome genetic deficiencies when it comes to her children’s survival.
Given these instincts, an optimal human sexual market would be one that “clears” only via committed monogamy. If sex is traded by women only to men who trade commitment, then everyone in the market can have their sexual instincts satisfied. Note that this social arrangement was the western ideal (if not reality) for many centuries: Men agreeing to long-term support of a woman and her offspring in exchange for that woman’s sexual availability and fidelity.
Another arrangement that has appeared frequently in human societies is committed polygyny (i.e., one man potentially committing to multiple women). Relative winners in this regime are alpha males and beta females. Women generally have a strong instinct for hypergamy (i.e., “marrying up” to obtain the best possible genes and/or resources for their children). Polygyny gives the most number of women access to the most desirable men. Losers in polygynous societies are alpha females (who can’t secure the commitment of alpha males, as they can in a monogamous society) and beta males (who are deprived of the chance to mate at all). A large population of unmated men tends to be destabilizing, so polygyny tends to work only when alpha males have enough power to contain those destabilizing forces, or else when the sex ratio of a population is highly skewed (e.g., due to protracted mortal warfare).
Hooking Up Smart links to a good essay by Robert Frank on modern marriage (a.k.a., Commitment) markets. Most of the blog’s content deals with the fallout of the western 20th-century “sexual/feminist revolution,” which vastly lowered the market price for Sex and consequently reduced the supply of Commitment. The consequences, for both society and individuals, have been terrible. The only winners in this regime seem to be alpha males and sexually sociopathic females. (And this is disregarding the toll taken by an explosion in sexually-transmitted diseases.)