The Price of Everything - Eduardo Porter [39]
Darwin’s theory of sexual selection posits that the first, most important driver of behavior—of humans or animals—is the imperative to pass genes down to future generations. In a world in which males need only invest a dollop of sperm in this endeavor, while females must produce an egg, carry, and nourish the embryo, it is only natural that mates would have asymmetrical reproduction strategies.
In the natural world this means that for males the ideal system would allow them to plant their seed in as many females as possible. Females, whose fertility is constrained by the enormous cost of bearing offspring, would have less use for multiple males. They would choose quality instead, males who could provide resources to help ensure that the next generation survived.
These are not the only considerations shaping the mating arrangement. Female bonobo apes are extraordinarily promiscuous. They have lots of sex, with whichever male happens to be around. Researchers suggest this behavior evolved as a strategy to avoid infanticide. Males would kill unrelated babies so their mothers would stop breast-feeding and recover their fertility. Indiscriminate sex ensured that a male could never be sure whether the kid was his.
Mating strategies are influenced by all sorts of ecological constraints—ranging from the abundance of food to the density of the population. Many species of birds establish stable monogamous relationships—an arrangement that reduces competition between females and ensures that males collaborate closely in the rearing of their offspring. But bird adultery is common—as males try to wriggle out of their marital strictures to maximize their reproduction potential while females try to find males with better genes than those of their faithful mates.
Still, the asymmetry between male and female investments in reproduction sheds light on many sexual mores. It helps explain, for instance, why cheating husbands usually choose women who are younger than their wives while cheating wives choose men who are more educated than their husbands. Men are most interested in women’s curves—a measure of their reproductive abilities—while women are most interested in men’s earning power—a measure of their command of resources. The asymmetry also explains why in many societies across the span of human history women have had a price.
POLYGAMY IS BRED of inequality. Polygamy is rare in subsistence societies, where resources are scarce, because males cannot sustain multiple females. And if all men are equally poor, women have little cause to choose to be the second wife of one man rather than the first wife of another. Polygamy became prevalent because it allowed economically successful men to extend their success to the market for reproduction, planting their seed in several mates. It also allowed more than one woman to mate with the most resourceful man and share his successful genes. This combination of incentives bred a market in which women sold reproductive services for men to bid for. The most resourceful men could offer more. This often led husbands to pay for their brides.
Roughly two thirds of the societies recorded in Murdock’s atlas feature payment for the bride. Among them are the Kipsigis, a polygamous society of herders and farmers in Kenya. The anthropologist Monique Borgerhoff Mulder, who studied the group in the 1980s and 1990s, found that each extra wife added 6.6 children to a man’s fertility. This fecundity—added to women’s contribution in labor to household income—commanded a price, usually paid by the groom to the bride’s family. From the 1960s to the early 1980s the average price for a Kipsigi bride was six cows, six goats, and eight hundred Kenyan shillings. For a man of average wealth, this amounted to one third of his cows, half his goats, and two months’ salary.
Yet prices followed the ebb and flow of supply and demand. Borgerhoff Mulder