April 16, 2014

Why Women Orgasm: Do We Really Know?

Female orgasm is similar to the male nipple: it is so strongly necessary and therefore selected for in one sex that it appears in the other sex.

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"Untitled (Del)" from the Rapture Series

"Untitled (Del)" from the Rapture Series

Popular culture has an obsession with the female orgasm. From When Harry Met Sally to Cosmo, we’re constantly asking what it is, how you go about having one, and how you distinguish an elaborate performance from the real deal. The question that’s asked less often is: why do women have orgasms at all? Orgasm, Elisabeth Lloyd, female orgasm

Orgasm as an Adaptation

Before thinking more deeply about that question, a quick lesson in evolutionary biology is in order. Biological traits can be adaptive, meaning that they came into existence as a result of natural selection and so increase the number of offspring an organism can have—for example, polar bears having thick fur to survive the arctic. They can also be non-adaptive, meaning that they have no effect on the organism’s current survival and ability to pass on its genes to the next generation—for example, the color of a fish that lives in a dark part of the ocean. Most theories about how the female orgasm evolved assume that it is an adaptive trait, meaning that having orgasms in some way increases a women’s fertility. These theories fall loosely into two groups: pair-bond theories and non pair-bond theories. Pair-bond theories assume that a primary purpose of sex is, to quote sociobiologist Desmond Morris, ‘cementing the pair-bond by providing mutual rewards for the sexual partners’. Essentially, orgasm would serve as an incentive to form a positive relationship with the partner with whom you are reproducing, ‘making sex sexier’ and increasing the number of surviving offspring by promoting bi-parental care of any children.  Non pair-bond theories, on the other hand, propose a more direct link with fertility. For example, the ‘upsuck’ theory states that the cervical contractions associated with orgasm draw sperm up into the uterus, increasing the probability of fertilization.

Do the theories fit the data?

Although ‘upsuck’ is a proven phenomenon in pigs, there’s no conclusive evidence that it operates in humans. Even ignoring this, adaptive theories more generally make a whole host of assumptions about the prevalence and incidence of female orgasm. As Elisabeth Lloyd points out in her book, ‘The Case of the Female Orgasm’, adaptive theories assume that female orgasms always or at least very frequently accompany penetrative sex. Indeed, this is a common misconception, one that causes many women to experience anxiety when they are not able to achieve orgasm through penetration. In actual fact, according to Lloyd, only 25% of women regularly orgasm from just intercourse, too small a number to signify that the trait was selected for by natural selection—other orgasms come about from oral or manual stimulation of the clitoris, and aren’t explained by these theories at all. So what, then, is the real story? Lloyd favors Donald Symons’ non-adaptive ‘by-product theory’. This states that female orgasm is similar to the male nipple: it is so strongly necessary and therefore selected for in one sex that due to similarities in embryological development it appears in the other sex. This theory doesn’t assume that orgasm has to accompany penile-vaginal sex, and it explains why female orgasm is so infrequent: if a trait has no effect, positive or negative, on an organism’s fertility, the rate at which is appears from individual to individual won’t necessarily be standard.

What does this mean for women?

Symons’ theory has, however, drawn some criticism from the feminist community for portraying female orgasm as just a derivative of—and therefore less significant than—the male sexual experience. However, as Elisabeth Lloyd points out, separating female orgasm from reproductive success could actually have a liberating effect for women. Orgasm becomes, in her words, a ‘freebie’. By accepting that female orgasm isn’t an adaptation for women—that orgasms had through penetrative sex aren’t more normal than those had in other ways—we can reduce the pressure and anxiety that many women feel about not having orgasms through penile-vaginal intercourse.