Do animals have orgasms?

Ah, the age-old question. When animals are going at it like, uh, animals, how does it end? Is there an animal version of the Big O?

It's a bit hard to say, actually. "The short answer is that we don't know much about orgasms in other species -- in fact, scientists are still studying the significance/evolution of female orgasms in humans," Marlene Zuk, a professor of ecology, evolution and behavior at the University of Minnesota, wrote me in an email.

Unlike humans, animals can't tell us they're having orgasms, so we can't truly know what their experience is like. For the most part, we assume that male animals orgasm because there's an ejaculation--though one can happen without the other, they usually go hand-in-hand. (Or something in hand.) The question of female orgasm is, as usual, more hotly contested, though all female mammals have clitorises.

Scientists can infer that animals--mostly primates--orgasm through recording physiological or behavioral aspects, like muscle contractions or changes in vocalization. Studies of primate orgasm have often focused on macaques, a subset of monkeys which are used often in research because they're genetically similar to humans and have similar reproductive systems. According to Alfonso Troisi, a clinical psychiatrist in Rome who has studied female orgasm in Japanese macaques, they're easier to study in the lab than gorillas or chimps. Macaques species tend to have longer copulations than other primate species like gorillas, which is a bonus if you're trying to observe their mating behavior.

"In the lab, by artificial stimulation, it is possible to trigger female orgasm in virtually any primate species."In a 1998 study, he and his co-author wrote that "Under specific circumstances, nonhuman primate females may experience orgasm." But, the rate at which the females orgasmed was variable, and they weren't exactly sure what caused them. Their study found that the level of dominance of the male macaque might play a role, for instance. But, as Troisi wrote me via email, "In the lab, by artificial stimulation, it is possible to trigger female orgasm in virtually any primate species."

At the Institute for Primate Studies in Norman, Okla., psychologist William Lemmon and his grad student, Mel Allen, argued that "the female chimpanzee manifests most, if not all, of the indices of sexual arousal and orgasm that occur in women."

They get more specific in the 1981 study:

sexual responses detected included transudate secretion, clitoral tumescence, vaginal thickening and expansion, hyperventilation, involuntary muscle tension, arm and leg spasms, clutching, facial expressions (eg, low open grin, low closed grin, eversion of the lips, protrusion of the tongue), and a panting vocalization.

Allen manually stimulated the clitorises and vaginas of female chimps in the course of writing his master's thesis at the University of Oklahoma, "Sexual response and orgasm in the female chimpanzee (Pan troglodytes)." (Surely he had fun describing his work at parties.) As he and Lemmon wrote in their later paper, "Most of these females permitted stimulation to continue to sexual arousal. One of them allowed stimulation to continue to orgasm on ten separate occasions." As they so dutifully recorded, the average number of "digital thrusts" required (performed "at an approximate rate of one to two per second") before the onset of vaginal muscle contractions: 20.3. Poor Allen.

Stanford University anthropologist Suzanne Chevalier-Skolnikoff, in 1974, writing on homosexual encounters between female stumptail macaques:

On three recorded occasions, the female mounter displayed all the behavioral manifestations of orgasm generally displayed by males: a pause followed by muscular body spasms accompanied by the characteristic frowning round-mouthed stare expression and the rhythmic expiration vocalization.

And yes, drawings were involved.

So, when it comes to primates, orgasms definitely seem to occur. What about the rest of the animal kingdom?

"Who knows whether it feels like a human [orgasm], but the external behaviour looks like it."The male red-billed buffalo weaver is the only species of bird we know of that exhibits orgasm-like behavior, according to Tim Birkhead, a professor in Sheffield University's Department of Animal and Plant Sciences. Birkhead spent years trying to observe the birds getting down, culminating in a study published in 2001. The buffalo weaver, a native of sub-Saharan Africa, has a fake penis--it has no sperm duct and doesn't become erect, but when Birkhead and his colleagues manually stimulated a buffalo weaver's mock member, the bird had what seemed to be an orgasm. As Birkhead described to me via email, "the bird shudders its wings and clenches its feet as it ejaculates-- who knows whether it feels like a human [orgasm], but the external behaviour looks like it." He says the organ is purely stimulatory, but they're currently investigating its anatomy further.

And what of dolphins, widely touted as the only other species to have sex for pleasure?

First of all, orgasms aside, animals don't get it on because they really want to make babies. They do it because it feels good (which ends up being good for the propagation of the species, too). As Daniel Bergner puts it in his book What Women Want:

The rat does not think, I want to have a baby. Such planning is beyond her. The drive is for immediate reward, for pleasure. And the gratification has to be powerful enough to outweigh the expenditure of energy and the fear of injury from competitors or predators that might come with claiming it. It has to outweigh the terror of getting killed while you are lost in getting laid. The gratification of sex has to be extremely high.

"Nowadays, there is little money around (even in the US), field researchers get no funds, and scientists working in the lab face the opposition of animal rights activists."Tadamichi Morisaka, an assistant professor at Kyoto University's Wildlife Research Center, says that dolphins do engage in masturbation without ejaculation "a lot," as well as other non-breeding-related genital touching, called socio-sexual behavior, especially between males. However, "We have no idea that dolphins feel orgasm or not because there is no study to measure brain response during sexual activity in dolphins," he told me via email.

Morisaka did catch the first spontaneous ejaculation ever recorded in a dolphin, which he published (with a mildly NSFW video) in a hyper-readable study in PLOS ONE. Spontaneous ejaculation has thus far been recorded in drowsy rats, guinea pigs, domestic cats, warthogs, horses and chimpanzees, according to the study.

As fun as this kind of research is to read about, watching animals get down in the hopes of detailing their climaxes in a scholarly manner appears to have gone out of style.

"The 1970s and 1980s were the golden years for primate research and animal ethology," according to Troisi, who left primate research a decade ago. "Nowadays, there is little money around (even in the US), field researchers get no funds, and scientists working in the lab face the opposition of animal rights activists. In addition, this the era of neuroscience and molecular genetics. Few people pay attention to behavioral observation," he wrote.

Other researchers echoed the sentiment. Kim Wallen, a professor of psychology at Emory University, says "animal studies have essentially disappeared."

According to Wallen, there have been a variety of factors involved in the demise of animal orgasm research. For one thing, it's easier to study human orgasms now that we can stick people in an fMRI scanner. Studying animal sex is hard--as evidenced by Birkhead's account to Nature of what it was like to chase around mating birds: "I'd run after them, sweating profusely with my binoculars steaming up."

Plus, the type of animal studies approved in the '70s and '80s might not make it past research review boards today. University of Toronto researcher Frances Burton's 1970 work, which involved hooking monkeys up in a dog-harness contraption and stimulating them with essentially a silicon monkey dildo, for instance, might be tough to get approved these days.

And though it's likely that most non-human primates have the ability to orgasm, we can't really know for sure if it's analogous to the human variety. As Zuk wrote me, "what all this points to is our own inability to know what other animals experience."

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