Why Women Have Sex (4 page)

Personal beauty is a greater recommendation than any letter of introduction.

—Aristotle (384–322 bce)

 

Despite its relative neglect in the history of psychology, sexual attraction is not simply a topic of titillation. It permeates our conversations—from gossip columns highlighting celebrity fashion missteps to Web sites devoted to ranking who is hot and who is not, advertisers exploit it to sell everything from cars to iPods. Lack of sexual attraction is often a deal breaker in romances, killing possible partnerships before they even get off the ground. And when sexual attraction fades with time, it can propel a partner into the arms of another. For many, sex provides a deep sense of exhilaration that makes them feel alive. We often cannot describe what it is that attracts us to another person. Sometimes we resort to
types—latching on to an easily identifiable trait or pointing to a celebrity who has many of the qualities we, and apparently many other people, find most appealing. Many women in our study mentioned a specific physical or personality characteristic that sexually attracted them, yet as many others chose to describe their sexual motivation in the simplest terms: I was attracted to the person. Women also said the person had a beautiful face; the person had a desirable body; the person had beautiful eyes; the person smelled nice; the person’s physical appearance turned me on; the person was a good dancer; or more graphically, the person was too physically attractive for me to resist.

This chapter explores what, exactly, women find sexually attractive—and why. Why do musky aromas and resonant voices stir women’s sexual desires? If women really are less sexually stimulated by visual images than men are, why do the faces of, say, Antonio Banderas and George Clooney excite so many women? Is there actually something in the way another person moves that can affect women’s sexual drives? How can a dazzling personality sometimes turn an average Joe into a man who exudes an irresistible animal magnetism? When does physical attraction overpower everything else?

Because the spark of attraction often operates beneath our consciousness, some of our answers to these questions come from an evolutionary perspective. Evolutionary psychologists start with the working premise that at least some of the characteristics that women find attractive are not culturally arbitrary. (The same is true of the characteristics that men find attractive.) Could the qualities that define sex appeal unconsciously provide signals of the benefits a woman might get from a potential mate? Biologists distinguish two broad classes of evolutionary benefits.
Genetic benefits
are the high-quality genes that can endow a woman’s children with a better ability to survive and reproduce.
Resource benefits
, including food, shelter from the hostile forces of nature, and physical protection from aggressive men, help a woman and her children to survive and thrive.

As we will see, some of the things that make women want to have sex with men have their roots in humans’ evolutionary past, while others have taken on a life of their own because of how we live, work, dress, and socialize today.

People are constantly coming into contact with one another—we are nestled into adjoining seats in college lecture halls, bump into strangers at coffee shops, move into neighboring houses on suburban cul-de-sacs, or spend long hours in catty-corner cubicles at the office. This proximity is often the first step in becoming attracted to someone.

Historically, you can see this in who people choose as their mates. Back in the 1930s, a study examined five thousand marriages performed in a single year, 1931, to determine where the bride and groom lived before their wedding. One-third lived within five blocks of each other and more than one-half lived within a twenty-block radius. Several studies over the decades have uncovered similar patterns. For example, in classrooms with assigned seating, relationships develop as a function of how far people are seated from each other. Students assigned to a middle seat are more likely to make acquaintances than those who are seated at the end of a row. With alphabetical seating, friendships form between those whose names start with nearby letters.

Although being near someone does not guarantee that a sexual spark will be struck, repeated contact (up to a point) with someone increases the odds. One study found that a series of brief—that is, no more than thirty-five-second—face-to-face contacts
without even talking to the person
increased positive responses. That is, we tend to like the people we see often more than those we see less frequently. In another study, four women research assistants with comparable physical attractiveness attended a college class. One research assistant attended the class fifteen times during the semester, one assistant attended ten times, another five times, and one not at all. None of the women had any verbal contact with the students in the class. At the end of the semester, the students, both men and women, rated how much they liked each of the research assistants. Attraction increased as the number of exposures increased, even though all of the research assistants were fundamentally strangers to the people in the class.

As it turns out, some amount of familiarity creates liking whether you’re talking about a person, a drawing, a word in an unknown foreign language, a song, a new product being advertised, a political candidate,
or even a nonsense syllable. The more frequent a person’s exposure during the crucial early period of introduction, the more positive the response. Why? We often respond to anyone or anything strange or novel with at least mild discomfort, if not a certain degree of anxiety. With repeated exposure, our feelings of anxiety decrease; the more familiar we are with someone, the better we are able to predict his or her behavior and thus to feel more comfortable around the person.

Once people are in close proximity, eye contact becomes important. The effect of mutual eye gaze is especially strong for women and men who are “romantics” by nature—those who believe in love at first sight, love for “the one and only,” and love as the key to relationships. In one study, forty-eight women and men came to a lab and were asked to stare into each other’s eyes while talking. The effect of mutual gaze proved powerful. Many reported that deep eye contact with an opposite-sex stranger created feelings of intense love. As one woman in our study put it:

I find it very arousing when someone is mysterious and doesn’t give too much of themselves away upon cursory review. I once had sex with a man because he was looking at me longingly but wouldn’t say much. It was a very passionate experience.

—heterosexual woman, age 33

Another study had strangers first reveal intimate details of their lives to each other for half an hour, and then asked them to stare into each other’s eyes for four minutes—without breaking eye contact or making any conversation. Participants again reported deep attraction to their study partners. Two of these total strangers even ended up getting married!

Too much familiarity, however, can backfire. Traits that are initially deemed positive can become a source of annoyance. Men who were once described as “funny and fun” become “embarrassing in public.” An attractive “spontaneity” transforms into an unattractive “irresponsibility,” “successful and focused” into “workaholic,” and “strong willed” into “stubborn.” Indeed, a certain amount of “mystery” can be sexually motivating for women, or for men for that matter. Not only can mystery stoke attraction; too much familiarity can quash it. As one woman said in her sexual memoir, “proximity can kill sex faster than fainting.”

Just as overexposure can douse the fire of sexual attraction, its opposite—novelty—can stoke its flames. Psychologist Daryl Bem sums it up with the phrase “the exotic becomes erotic.” Indeed, in college classes in which instructors ask women to list the qualities they find sexually attractive, “mysterious” invariably emerges on the list.

Humans come blessed with five known senses—sight, sound, smell, touch, and taste—and the sensory cues that enter into attraction tend to have greater effect with physical closeness. That’s particularly true when considering one of the strongest ingredients in sex appeal, one long neglected by the scientific community: women’s acute sense of smell.

Scents are famously known to carry strong psychological associations—think about how a whiff of a loved one’s favored perfume or cologne can bring to mind the person who wore it, along with a cascade of emotions. Partly, this is due to the unusual design of the olfactory nerve, which extends in a network throughout the brain—unlike the nerves carrying information for the other major senses, which are less wide-ranging. This architecture helps the brain to tie memories of emotional events with olfactory information. The emotion-stirring aspect of smell is important; but smell also turns out to be surprisingly important to women when it comes to basic sexual attraction.

Using an instrument called the “Sensory Stimuli and Sexuality Survey,” researchers at Brown University found that women rate how someone smells as the most important of the senses in choosing a lover, edging out sight (a close second), sound, and touch. One woman in our study ranked the attractions of a sexual partner:

I was attracted to his smell, his eyes, and his demeanor. Also, his French accent.

—heterosexual woman, age 23

How a woman smells to a man, in contrast, figures less heavily in his sexual attraction. Perhaps it is because men’s sense of smell is less acute than women’s. Perhaps it is because visual cues loom so much larger in
what turns men on. And it’s not just that women think smell matters in whether they are attracted to someone, it’s that women’s sexual arousal is enhanced by good body odors—and killed by bad ones.

One reason why body odors play such an important role in women’s sexual attraction has come to scientific light only recently. The first clue came from an unusual discovery: that a woman’s olfactory acuity reaches its peak around the time of her ovulation, the narrow twenty-four-hour window during the monthly menstrual cycle in which she can become pregnant. This led scientists to suspect that women’s sense of smell might play a role in reproduction. It was not until researchers began to explore the body’s defenses against disease, however, that the connection was made.

The genes responsible for immune functioning—fighting off disease-causing bacteria and viruses—are located within the major histocompatibility complex, or MHC, found on chromosome 6. Different people have different versions, or alleles, of these MHC genes; in the jargon of geneticists, the MHC genes are “polymorphic.” It turns out that women can benefit in two ways from mating with men who are
dissimilar
to themselves in MHC genes. First, a mate with dissimilar MHC genes likely has more dissimilar genes in general, and so finding an MHC-dissimilar person attractive might help to prevent inbreeding. Reproducing with close genetic relatives can be disastrous for the resulting children, leading to birth defects, lower intelligence, and other problems. But a second benefit of mating with someone with complementary MHC genes is that any resulting children will have better immune functioning, making them better able to fight off many of the parasites that cause disease.

The puzzle is how women could possibly be able to choose mates who have complementary MHC genes in order to give these benefits to their offspring. In a revealing study, Brazilian researchers had twenty-nine men wear patches of cotton on their skin for five days to absorb their sweat—and thus their body odors. A sample of twenty-nine women then smelled each cotton patch and evaluated the odor on a dimension from attractive to unattractive. Scientists identified the specific MHC complex of each man and woman through blood assays. Women found the aromas of men who had an MHC complex complementary to their
own smelled the most desirable. The odors of men who had an MHC complex similar to their own made them recoil in disgust. Amazing as it may seem, women can literally smell the scent of a gene complex known to play a key role in immune functioning.

This highly developed sense of smell can have a profound effect on women’s sexuality. University of New Mexico evolutionary psychologist Christine Garver-Apgar and her colleagues studied MHC similarity in forty-eight romantically involved couples. They found that as the degree of MHC similarity between each woman and man increased, the woman’s sexual responsiveness to her partner decreased. Women whose partners had similar MHC genes reported wanting to have sex less often with them. They reported less motivation to please their partner sexually compared to the women romantically involved with men with complementary MHC genes. Perhaps even more disturbing to their mates (if they knew), women with MHC-similar partners reported more frequent sexual fantasies about other men, particularly at the most fertile phase of their ovulation cycle. And their sexual fantasies about other men did not just remain in their heads. They found themselves in the arms of other men more often, reporting higher rates of actual sexual infidelity—a 50 percent rate of infidelity among couples who had 50 percent of their MHC alleles in common.