Why Women Have Sex (30 page)

Our own study of why women have sex confirmed that Michigan undergraduates are not alone in their sexual motivations. Among the reasons women listed:

Nor is sexual barter limited to Americans. Exchanges of gifts and sex occur in every culture. Anthropologist Donald Symons set out to elucidate this phenomenon from a cross-cultural perspective. Using the Human Relations Area Files, considered to be the most massive database of ethnographic studies, Symons categorized gifts that were received in contexts such as courting, wooing, and extramarital affairs, determining whether men or women or both gave the gifts, whether the gifts occurred between lovers or directly in exchange for sex, and the relative value of the gifts given. The gifts were identified along the following lines: 1) only men give gifts; 2) men and women exchange gifts, but men’s gifts are of greater value; 3) men and women exchange gifts and there is no mention of relative value (in no cases were men’s and women’s gifts specifically stated to be of equal value); 4) men and women exchange gifts, but women’s gifts are of greater value; 5) only women give gifts. He specifically excluded from his analysis gifts given in the context of marriage and paid prostitution.

To his surprise, Symons discovered that the fourth and fifth categories proved entirely unnecessary, since not a single society met their criteria. In contrast, 79 percent of societies fell predominantly into the first category, with only men giving gifts; 5 percent fell into the second category, in which both sexes gave gifts, but men’s gifts were more valuable; and the remaining 16 percent of societies fell into the third category, in which there was no mention of the gifts’ relative value. As a heterosexual woman in our study put it, “Sex equals gifts.”

It is especially intriguing to find this sexual asymmetry in cultures high in sexual equality and in which there is tremendous sexual freedom and opportunity for both sexes. Anthropologist Marshall Sahlins’s studies of the Trobriand islanders provide an interesting illustration. Trobriand women expect gifts in exchange for sex:

In the course of every love affair the man has constantly to give small presents to the woman. To the natives the need for one-sided payment is self-evident. This custom implies that sexual intercourse, even where there is mutual attachment, is a service rendered by the female to the male. . . . This rule is by no means logical or self-evident. Considering the great freedom of women and their equality with men in all matters, especially that of sex, considering also that the natives fully realize that women are as inclined to intercourse as men, one would expect the sexual relation to be regarded as an exchange of resources itself reciprocal. But custom . . . decrees that it is a service from women to men, and men have to pay.

These observations, along with an avalanche of other findings, strongly support a basic fact about human economics: Women’s sexuality is something that women can bestow or withhold, something that men want and value highly, and consequently something that women can use to secure resources that they desire. Women, in short, have the power in many sexual transactions.

In the most traditional hunter-gatherer cultures, the transaction is an exchange of sex for food. Among the Sharanahua of Peru, for example, “Whether men prove their virility by hunting and thus gain wives or offer meat to seduce a woman, the theme is an exchange of meat for sex.” Janet Siskind, the anthropologist who studied the Sharanahua expressed bafflement at this since she knows “of no real evidence that women are naturally or universally less interested in sex or more interested in meat than are men.” Yet one woman in our study made a strikingly similar point:

Being “gifted” for sex, or financially compensated, provides a stimulus of excitement with a wealthy man equivalent to passion with a physically powerful man. Financial protection equals physical protection.

—heterosexual woman, age 58

The key issue is not whether women and men differ in their enjoyment of sex, nor whether the sexes differ in their interest in having sex (let alone in consuming meat!). The mystery is why women sometimes seem to hold such a commanding position in the economics of sex.

The most plausible evolutionary answer to the mystery of women’s greater power in the sexual arena—why women’s sexuality is so valuable and seemingly scarce that men worldwide willingly pay for it—lies with the fundamental asymmetries in human reproductive biology, and the sexual psychology that has evolved as a consequence.

We’ve already seen how women’s hefty investment in pregnancy, when viewed from an evolutionary perspective, has favored a sexual psychology that seems to make women less desirous of having multiple sexual partners. But the gender differences in reproductive biology really start with the asymmetries between sperm and egg. Sperm are little more than genes traveling an eighth of an inch per minute via a stripped-down swimming machine. Sperm are dwarfed in size by women’s nutrient-filled eggs. The normal human sperm is a mere three microns wide and six microns long, while the normal human ovum, at maturity, is a whopping 120 to 150 microns in diameter. So from the very start of conception, women make a larger contribution than men do. Compounding the asymmetry, women are born with a fixed number of eggs, which cannot be replenished. Men, in contrast, produce roughly 85 million new sperm each day. Today, these differences in relative value play out in how much women get paid for donating their ova versus how much money men get paid for donating sperm. Compensation for egg donation usually starts at five thousand dollars, and can be several times that amount for women who meet certain physical and psychological conditions. Sperm donors, in contrast, typically receive only $35 per donation, although some with highly desirable traits—such as height, a V-shaped torso, an attractive face, high intelligence, and high social status—may get as much as $150.

This difference between the sexes widens as a consequence of the nine-month pregnancy that women endure in order to produce a child. Women’s heavier reproductive investment in producing their offspring means they are by far the more valuable reproductive resource. As a general rule, the more valuable the resource, the more people compete for access to it. Men must compete with each other for sexual access to women. Women can afford to be choosy since they are in greater demand when it comes to sex.

Evolutionary psychologists posit a number of explanations for women’s disproportionate sexual power. The first derives from men’s evolved sexual strategy for what is called short-term, low-investment mating. Because ancestral men could increase their purely
reproductive
success by having casual, no-strings-attached sex with multiple partners, one component of their evolved sexual psychology is a desire for access to mates. The
desire for sexual variety
is reflected in men’s sexual fantasies, which are far more likely than women’s fantasies to focus on sex with strangers, multiple partners, and partner switching during the course of a single episode. Men are four times as likely as women to report having had sexual fantasies about more than a thousand different partners. Although there may be some reporting bias—perhaps because women are culturally conditioned to be more reticent about disclosing information about their sexuality than are men—the sex differences are profound and verified by many studies. Because of men’s desire for sexual variety, women, in men’s eyes, are perpetually in short supply.

Men possess another psychological tic, the
sexual overperception bias
, which is the tendency to overinfer women’s sexual interest based on ambiguous information. As demonstrated in the evocations of jealousy described in chapter 5, when a woman smiles at a man, men often infer sexual interest, when in many cases the woman is simply being friendly or polite. Other ambiguous cues—a touch on the arm, standing close, or even holding eye contact for a split second longer than usual—trigger men’s sexual overperception bias. As a consequence, women can exploit men’s overperception bias for economic gain, in what has been called a “bait and switch” tactic, a strategy that involves persuading men to expend resources as part of courtship, but then failing to follow through on an implied “promise” of sex.

Research has also found that most men find most women at least somewhat sexually attractive, whereas most women do not find most men sexually attractive at all. The Buss Evolutionary Psychology Lab discovered that men lower their attraction standards for casual encounters. Empirically, they are willing to have sex with partners who meet just minimal thresholds on traits they themselves rank as desirable, such as intelligence and kindness. In contrast, women typically maintain
high standards in whom they choose, whether for casual or pair-bonded sexual encounters.

Several other gender differences in how women and men are sexually aroused and respond to arousal cues give women extra leverage in sexual economics. Men are generally more likely than women to become sexually aroused through visual stimulation. Simply the sight of an attractive woman can lead a heterosexual man to become aroused, and this gives women, who tend to be less keyed to visual attractions, an edge. Men also appear to be less willing to tolerate states of sexual abstinence and to have a greater drive to have sexual intercourse, regardless of circumstances.

It is important to keep in mind that men do not have a conscious motive to “spread their seed.” Furthermore, the desire for sexual variety and quantity reflects just one of their mating strategies, and most men also seek long-term committed relationships. But men’s shorter-view sexual psychology produces a mating market in which the sexual services of women are in top demand. In the modern environment, this gives women an opportunity to extract value from sex through prostitution, sexual barter, and ongoing mating relationships.

I worked at a legal brothel in Nevada for approximately three years. I wasn’t very good at it, by the way, having too much attitude for the clientele, but [I] managed to keep the job. . . . I do not necessarily includ[e] this time period as . . . relevant to my “sex life,” as it was work. I didn’t have anywhere else to go in life, and the other girls at the house became very much like family.

—predominantly heterosexual woman, age 36

Within the broader ambit of what motivates women to have sex, our goal is to understand the sexual psychology that drives women to prostitution. While we will not take an ideological stand on this topic, it is worth noting the spectrum of political and moral beliefs about prostitution, since the ability of a woman to gain resources from it is limited by laws, social mores, and religions.

On one end, there are people who argue that prostitution should be illegal and criminalized because it is degrading to women. It makes them vulnerable to being used and abused by men. It causes women to be treated as sex objects or commodities. And, according to some thinkers, it maintains men’s political dominance over women. Some of these arguments have held sway. In fact, prostitution is illegal in some places, including most of the United States. Nonetheless, there are far more countries where prostitution is legal—including most of Europe, Mexico, most of South America, Israel, Australia, and New Zealand. Prostitution is also legal in some counties within the state of Nevada.

Even in countries in which prostitution is illegal, there are sometimes very large loopholes for circumventing the restrictions. In Iran, for example, prostitution is illegal, and it is a crime to advocate it, to assist a woman in becoming a prostitute, or to operate a brothel. Those found guilty can be—and often are—executed by firing squad or stoning. Yet historically Iran has allowed a practice called
mutïa
, in which women become “temporary wives” for a few hours in an exchange of sex for money. In the Philippines, prostitution is illegal, but some employees of bars are given the euphemistic title “customer relations officer” and required to be tested for sexually transmitted diseases once a week. In Thailand and other countries, prostitution is illegal, but the laws are rarely enforced. Most countries that have legalized prostitution impose various restrictions. Some, such as England and Scotland, make it illegal to proffer or solicit sex on the streets but permit “outcall” sexual escort services, meaning that prostitution is okay as long as it remains private rather than public. In Canada, prostitution, brothels, and outcall escort services are fully legal, but “pressing and persistent” solicitation on the street is illegal.

With prostitution so common, even in countries in which it is mostly or wholly illegal, some people advocate that governments should not consider prostitution to be a crime and give women the right to use their bodies in any way they wish. As one former prostitute argued: