The Orgasm Wars

For years, scientists have been debating the function of female orgasm. Nowthey've finally figured it out. For women, the psychology of sexual satisfaction turns out to be much more sophisticated than most (male) scientists have been willing to concede. Of course.
Ever since Alfred Kinsey and Masters and Johnson made the subject of human sexual response safe for respectable scientists, laboratory studies of the physiologic "hows" of sexual arousal have flourished. Volunteers have been prodded, filmed, tape-recorded, interviewed, measured, wired, and monitored, quantifying for the annals of science the shortened breath, arched backs and feet, grimacing faces, marginally intentional vocalizations, and jumping blood pressure of human orgasm.

While physiological details abound, fewer scientists have attempted to answer the "why" questions about human orgasm. To those who view human behavior in an evolutionary framework, which we believe adds an invaluable perspective, male orgasm is no great mystery. It's little more than a physiologically simple ejaculation that is accompanied by a nearly addictive incentive to seek out further sexual encounters. The greater the number of inseminations a male achieves, the better his chances of being genetically represented in future generations.

Compared with the more frequent and easily achieved orgasm men experience, women's sexual climax has remained a mystery. After all, women do not need to experience orgasm in order to conceive. So what is the function of orgasm in females?
Darwinian theorists who made early attempts to address female orgasm proposed that orgasm keeps a woman lying down after sex, passively retaining sperm and increasing her probability of conception. Others suggested that it evolved to create a stronger pair bond between lovers, inspiring in women feelings of intimacy and trust toward mates. Some reasoned that orgasm communicates a woman's sexual satisfaction and devotion to a lover.

Most recently, evolutionary psychologists have been exploring the proposition that female orgasm is a sophisticated adaptation that allows women to manipulate—even without their own awareness—which of their lovers will be allowed to fertilize their eggs.
Male Nipples?
The diversity of evolutionary hypotheses reflects one general attitude: that the quickened breath, moaning, racing heart, muscular contraction and spasms, and nearly hallucinatory states of pleasure that orgasm inspires constitute a complex physiologic event with apparently functional design. But critics of adaptationist hypotheses have long argued that evolution is more slipshod than purposeful. A few, including Harvard evolutionist Stephen lay Gould, have insisted that female orgasm probably doesn't have a function.

Instead, Gould argues, female orgasm is incidental, caused by an anatomical peculiarity of embryonic development. In embryos, the undifferentiated organ that later becomes the penis in males becomes the clitoris in females. Antiadaptationists like Gould--whose thinking uncannily parallels Freud's belief that women spend their life in penis envy--hold that the clitoris is, biologically speaking, an underdeveloped penis; it can let women mimic male orgasm, but it has no functional relevance or evolutionary history of its own.

Well known for his emphasis on chance events and structural constraints as major players in the evolutionary process, Gould sees the supposed functionlessness of female orgasm as a classic illustration why scientists ought not automatically assume that a trait has adaptive significance. He criticizes other evolutionists for overemphasizing natural selection and functionality, and concludes that female orgasm is like the male nipple--nothing more than developmental baggage.

Many evolutionists have rejected Gould's notion that women's orgasms are developmentally contingent on men's. Unlike a male nipple, adaptationists have pointed out, the female orgasm does something. It inspires strong emotions that can affect bonding and sexual preferences, making women more likely to prefer the company of one mate over another.

Only during the past few years have studies begun to yield evidence that may resolve the baggage-versus-adaptation debate over women's orgasms.
Sperm Competition, with Women Judging
Clues for a reasonable adaptation hypothesis were readily available by the late 1960s, when The British Medical Journal published an exchange of letters about the muscular contractions and uterine suction associated with women's orgasm. In one letter, a doctor reported that a patient's uterine and vaginal contractions during sex with a sailor had pulled off his condom. Upon inspection, the condom was found in her cervical canal! The doctor concluded that female orgasms pull sperm closer to the egg as well.

Yet, it was only three years ago that two British biologists, Robin Baker and Mark Bellis, tested the so-called upsuck hypothesis. They were building upon ideas articulated by evolutionary biologist Robert Smith, who suggested that since women don't have orgasms every time out, female orgasm favors some sperm over others. Baker and Bellis sought to learn just how female orgasms might affect which of a lover's sperm is used to fertilize a woman's eggs.

They asked volunteers to keep track of the timing of their orgasms during sex, and, after copulation, to collect male ejaculates from vaginal flowback--a technical term denoting a distinct form of material that emerges from the vagina several hours after sex (scientists have devised a way to collect it). The team counted sperm from over 300 instances of human copulation.

They discovered that when a woman climaxes any time between a minute before to 45 minutes after her lover ejaculates, she retains significantly more sperm than she does after nonorgasmic sex. When her orgasm precedes her male's by more than a minute, or when she does not have an orgasm, little sperm is retained. Just as the doctors' letters suggested decades earlier, the team's results indicated that muscular contractions associated with orgasm pull sperm from the vagina to the cervix, where it's in better position to reach an egg.

Baker and Bellis proposed that by manipulating the occurrence and timing of orgasm--via subconscious processes--women influence the probability of conception. So while a man worries about a woman's satisfaction with him as a lover out of fear she will stray, orgasmic females may be up to something far more clever--deciding which partner will sire her children.

Good Men Are Hard To Find
Meanwhile, other researchers were making discoveries about the nature of male attractiveness. Behavioral ecologists had noted that female animals, from scorpion flies to barn swallows,