Why do women have orgasms? This is one of the big puzzles of evolutionary psychology. The purpose of male orgasm seems perfectly plain to (male) psychologists—it rewards men for their diligent efforts at continuing the species. Congratulations, gentlemen! Give yourselves a pat on the back for your valiant efforts.
While an orgasm invariably accompanies male ejaculation, women are perfectly capable of getting pregnant without one. All they have to do is lie back and provide a fertile womb to receive their man’s virile seed. Or so was the received (male) wisdom. Indeed, during Victorian times, it was generally believed that women didn’t have orgasms—at least not proper ladies! We can thank Freud and friends for dismissing that ill-conceived notion.
Even once (male) psychologists came around to the idea that women do indeed have orgasms, they still found it a mystery in need of explanation. Here are some of the male-centric theories offered over the years:
Vestige theory. Just as males have vestigial nipples, females have vestigial penises in the form of a clitoris. And since clitorises are really just shrunken penises, women can still have orgasms, even though they don’t need to. Or so goes the theory, even though there are plenty of problems with it. First, vestigial male nipples are nonfunctional—they don’t produce milk. So a clitoris-as-vestigial-penis shouldn’t be functional either. However, the clitoris has just as many nerve endings as the penis, hardly what you’d expect from a vestigial organ. And second, the basic body plan is female, which is why males have nipples in the first place. But this also means the penis is really just a large clitoris protruding from the male body.

Up-suck theory. Evidence suggests that orgasm creates a slight vacuum in the uterus which can draw in the man’s ejaculate. But this process requires the woman to orgasm at around the same time as the man. Like winning the lottery, simultaneous orgasms are certainly grand experiences, even though the likelihood of occurrence is exceedingly small. As all good lovers know, it’s “Ladies First.” And besides, few women orgasm through penetrative sex alone, and most need direct stimulation of the clitoris. So timing is really bad for up-suck theory.
By focusing on the reproductive aspects of sex, psychologists may be missing the real purpose behind orgasm. In a recent article, SUNY Albany psychologist Gordon Gallup and his colleagues rethink the evolutionary origin of the orgasm—both male and female.
They start off by noting that orgasms simply aren’t a necessary component of reproduction, as sex drive alone will accomplish that. For example, salmon mate only once in their life, and then they die. The power of their sex drive is evident in the long distances they swim under arduous conditions to reach their native spawning ground. There, the female lays her eggs in a ditch, and the male spews his sperm atop them—none of the bump-and-grind kind of sex that we mammals engage in. Gallup and colleagues argue that there’s no reason to think that salmon derive any pleasure from the sexual act, just an end to the horniness.

Still, birds and mammals generally only have sex when the female is ovulating. This means that sex for these animals isn’t a “shot in the dark,” as there’s a high probability of copulation leading to fertilization. Cats and dogs apparently enjoy their sexual encounters, judging from all the noise they make. But what’s less clear is whether they ever get a “big bang” out of it.
When it comes to humans and their cousins, the chimpanzees and bonobos, sex gets more complicated. For whatever reason, females in these species have developed hidden estrus, meaning that there are no obvious signs of ovulation. And since women are only fertile one or two days a month, that means couples have to have lots of sex of they want to make a baby.
If you only have sex once in your life or only when “she’s ready,” sex drive is enough to motivate reproduction. It’s only when sex needs to be repeated frequently that an added incentive is important, and that’s where the “Big O” comes in. This, in a nutshell, is the argument that Gallup and his colleagues make.

But humans take sex to an even higher level. Unlike chimps and bonobos, humans pair-bond for the purposes of raising children. Pair-bonding is common among songbirds but rare among mammals, including primates. Apparently, what keeps human fathers around is the opportunity to engage in frequent recreational, orgasm-inducing sex with their mate. After all, humans not only have sex a lot before pregnancy, but also during it and after childbirth, when the mother is lactating and can’t ovulate. In other words, orgasm serves a social purpose by helping build pair-bonding relationships—at least for heterosexual males.
Again, though, we get to the question of why females orgasm. Gallup and colleagues suggest that orgasm is a signal to the female that she’s mating with a “high quality” male. Studies find that women experience more orgasms when they mate with men who are very attractive, masculine, or wealthy—all signs that he’s got good genes. Furthermore, women who have extramarital affairs are more likely to orgasm with their illicit lovers than with their husbands. Presumably, they only risk infidelity when the “other man” is considerably better that what they’ve got back home.
This line of reasoning leads Gallup and colleagues to a discussion of female anorgasmia. Specifically, they suggest that many women don’t achieve orgasm during intercourse because they fail to find “high quality” sexual partners. For example, they maintain that some women just don’t know how to attract quality men, or else they’re unwilling to do what it takes. The researchers note studies showing that even though sexual attitudes have become far more open over the last thirty years, levels of female anorgasmia have remained constant. So it’s not just that women are stuck with their “low-quality” husbands, as they once were. Nowadays, many women go from one unsatisfying sexual relationship to another, rarely if ever experiencing any pleasure in those unions. These women need to rethink the strategies they’re using to attract men or reconsider the type of men they think they find attractive.
But men also need to own up to their responsibility and see to it that they’re properly pleasuring their partner during intercourse. Not all men can have fantastic genes that give them square jaws, bulging biceps, and chiseled abs. But men can do their best to stay in good health, groom properly, and be dependable providers. These are also traits of “high-quality” males that many women find attractive. And in the bedroom, they have to get beyond the attitude that “what’s good for me is good for her.” Women rarely orgasm during penetrative sex. Instead, they need clitoral stimulation, and lots of it. I imagine many women will agree that the attentive lover who meets his partner’s needs before his own is a mate of the highest quality.