by Jesse Bering
Not So Fast … What’s So “Premature” About Premature Ejaculation?
It occurred to me recently, under conditions that I leave to your ample and likely sordid imagination (how dare you), that the very concept of premature ejaculation in human males is a strange one, at least from an evolutionary theoretical perspective. After all, the function of ejaculation isn’t really a mysterious biological occurrence: it’s an evolved mechanism designed by nature to launch semen, and therefore sperm cells, as far into the dark, labyrinthine abyss of the female reproductive tract as possible. And once one of these skyrocketed male gametes, in a vigorous race against millions of other single-tasked cells, finds and penetrates a fertile ovum, and—miracle of miracles—successful conception occurs, well, then, natural selection can congratulate itself on a job well done.
So given these basic biological facts, and assuming that ejaculation is not so premature that it occurs prior to intromission and sperm cells find themselves awkwardly outside of a woman’s reproductive tract flopping about like fish out of water, what, exactly, is so “premature” about premature ejaculation? In fact, all else being equal, in the ancestral past, wouldn’t there likely have been some reproductive advantages to ejaculating as quickly as possible during intravaginal intercourse—such as inseminating as many females as possible in as short a time frame as possible? Or allowing our ancestors to focus on other adaptive behaviors aside from sex? Or perhaps, under surreptitious mating conditions, doing the deed quickly and expeditiously without causing a big scene?
Like so many things before, it turns out that this insight of mine was actually several decades behind the curve, because in 1984, when, at nine years of age, I was still anything but a premature ejaculator, a sociologist named Lawrence Hong published a highly speculative but very original paper along these same lines that’s worth engaging with here, fittingly titled “Survival of the Fastest: On the Origin of Premature Ejaculation.” In this article, Hong—whose most recent work, as far as I can tell, has been on the global phenomenon of cabaret transgenderism—posited that during the long course of human evolutionary history, “an expeditious partner who mounted quickly, ejaculated immediately, and dismounted forthwith might [have been] the best for the female.”
The empirical centerpiece of Hong’s arriving at this conclusion is the fact that on average, human males achieve orgasm by ejaculating just two minutes after vaginal penetration, whereas it takes the owners of these vaginas, on average, at least twice that long to do the same once a penis is inside of them—if they achieve orgasm at all, that is. This obvious gender mismatch between orgasm latencies can be understood, Hong reasons, only once we acknowledge that sex evolved, at least initially, for purely reproductive purposes. Don’t forget, he reminds us, that recreational heterosexual sex is enabled only by relatively recent technological innovations, such as contraceptive devices.
Hong compares the mating habits of human beings with those of other rapid—and not-so-rapid—ejaculators in the primate family, noting that the faster a primate species is in the coital realm, the less aggressive it is when it comes to mating-related behaviors. He calls this the “slow speed–high aggressiveness hypothesis.” For example, male rhesus macaque monkeys often engage in marathon mounting sessions, where sex with a female can be drawn out for over an hour at a time (including many breaks and therefore noncontinuous thrusting). That may sound great, but libidinous anthropomorphizers beware: macaque sex is a chaotic and violent affair, largely because the duration of the act often draws hostile attention from other competitive males. By contrast, primate species whose males evolved to ejaculate rapidly would have largely avoided such internecine violence, or at least minimized it to a considerable degree.
Key to Hong’s analysis is the idea that intravaginal ejaculation latencies in males are heritable; there was initially greater within-population-level variation in our male ancestors, he surmises, but over time “the ancestry of Homo sapiens became overpopulated with rapid ejaculators.” According to Hong, this is because young reproductive-aged males who ejaculated faster (that is, had more sensitive penises) avoided injury, lived longer, and therefore had a greater chance of attaining high status and acquiring the most desirable females.
Hong’s reasoning on these heritability grounds has in fact received recent support. You may have missed this in your monthly periodical readings, but in a 2009 article from The International Journal of Impotence Research a team of Finnish psychologists led by Patrick Jern reported evidence from a large-scale twin study showing that premature ejaculation is determined significantly by genetic factors. Thousands of male twin pairs—fraternal and identical—completed a survey about how long it took them to reach orgasm; and the timing of identical twins was more closely matched than fraternal twins. So just as Hong surmised many years ago, this is indeed a heritable trait; if you doubt it, go on, have that awkward conversation with your fathers, boys. In fact, since Jern and his colleagues found that delayed ejaculation—the other extreme end of the ejaculation latency continuum—revealed no such genetic contributions, these authors generally agree with Hong, postulating that “premature” ejaculation may be a product of natural selection whereas delayed ejaculation “would be completely maladaptive.” Delayed ejaculators are considerably rarer, with a prevalence rate as low as 0.15 percent in the male population compared with as high as 30 percent with premature ejaculators, and their condition is usually owed to lifelong medical conditions or the recent use of anti-adrenergics, selective serotonin reuptake inhibitors, neuroepileptics, or other modern-day drugs that are often associated with anorgasmia as a miserably unfortunate side effect.
Adding further credence to the evolutionary model is a separate set of self-report data published in The Journal of Sexual Medicine, in which Jern and colleagues demonstrated that ejaculation latencies were significantly shorter when men achieve orgasm through vaginal penetration than when doing so in the course of other activities, such as anal, oral, or manual sex. In fact, in light of these differential ejaculation latencies, they argue that the very construct of such male orgasmic “timing” is best carved up by discrete sexual behaviors rather than treated as a more general clinical phenomenon. And they offer several helpful acronyms for these ejaculation latency subtypes, too, such as “OELT” for “oral ejaculation latency time” and, conveniently, “MELT” for “masturbation ejaculation latency time.”
I have the niggling, faraway sense that we’ve left something out of the evolutionary equation regarding the variation in male ejaculation latencies. What, oh what, can that possibly, conceivably be? Oh, come now, I know it’s women’s sexual satisfaction. Actually, Hong didn’t leave female orgasms out of his rather viscous analysis altogether; he just didn’t see them as being central to selective pressures. Presumably, like other theorists of that time writing about the biological reasons for female orgasms (such as Stephen Jay Gould, who thought that female orgasms were much like male nipples, a happy leftover of the human embryological Bauplan), he saw women’s sexual pleasure as being a nice, but neither here nor there, feature of human sex that nature had thrown into the mix.
Hong acknowledges—with great humility and humor, in fact—that his ideas on the evolutionary origins of premature ejaculation in human males are mostly guesswork. And his ideas were critiqued by the psychologist Ray Bixler in his review of Hong’s theory. Among many faults that Bixler finds in Hong’s “survival of the fastest” theory, the basic logic just doesn’t mesh with the obvious female pursuit of sexual intercourse. In chimpanzees, for instance—a species for which male ejaculation latencies are measured in seconds, not minutes—it is often females who initiate mating behaviors. And then there’s the “ouch” factor of having a nonaroused female partner whose dry genitals aren’t terribly inviting. If Hong’s model were correct, says Bixler, “there would be little or no proximal cause, other than coercion, for female cooperation—and it should be very clear that she would have to cooperate if voluntary mating
were to be speedy! If she were not lubricated he would have ‘to rasp it in,’ a painful experience for the woman, and … ‘no pleasure’ for him either.”
Disappointingly, this is more or less where the evolutionary thinking stops on this subject. Apparently, no other theorist—at least no experimentally inclined evolutionary theorist—has picked up Hong’s lead in trying to tease apart competing adaptationist arguments regarding male ejaculation latencies. Pieces of the puzzle are floating about out there, I suspect, such as the Finnish research showing that vaginal sex leads to faster ejaculations compared with other sexual behaviors. But Hong’s article was before its time—premature itself, in light of today’s more informed evolutionary biology, which is now poised to construct a more nuanced empirical model about this evolutionary legacy that is behind so many of us being fast finishers.
Another big piece of the puzzle may be linked to our species’ uniquely evolved social cognitive abilities. Possibly only tens of thousands of years ago, just a splinter of a splinter’s time in the long course of our primate history, ancestral humans may have become the only species capable of experiencing empathy with our sexual partners during intercourse. Men could then think about satisfying their partners during sex rather than just themselves, thus deliberately prolonging the act of coitus to delay their own orgasm for her sake. Prior to this, our more distant ancestors may have been more like chimpanzees, seeing others’ bodies as mindless meat.
Given the unpleasant stigma attached to premature ejaculation, an evolutionary approach to the “problem” could greatly inform clinical treatments, a (not surprisingly) high-grossing therapeutic area in which there is no shortage of work being done. But in any event, Hong’s seminal ideas should give us all pause in labeling any particular intravaginal ejaculation “premature”; Mother Nature, arguably the only lover that really matters, after all, may very well have had a thing for our one-minute ancestors.
An Ode to the Many Evolved Virtues of Human Semen
I have come upon a secret treasure, a heretofore-unknown bounty of facts only recently unearthed by a team of evolutionary psychologists. A vital forewarning, though: although the data and information I am about to share ooze with the promise of dramatically improving virtually every aspect of your well-being, it can also be abused with tragic—even fatal—consequences. This is so much the case, in fact, that I debated the merits of popularizing this material and do so here only with great circumspection and caution. So please be wise in digesting this semen-related knowledge, and be wiser still in applying it to your own sex lives.
As with the origins of so many great scientific discoveries, this story begins with a serendipitous chain of events. “Our interest in the psychological properties of semen arose as a by-product of an initial interest in menstrual synchrony,” explain the codiscoverers Gordon Gallup and Rebecca Burch, writing about human semen. In particular, Gallup and Burch had stumbled onto a set of curious data from the mid-1990s showing that unlike heterosexually active women residing together, partnered lesbians sharing a residence failed to exhibit the well-known “McClintock effect,” in which menstrual cycles in cohabiting women (as well as those of females from many other species) are synchronized. Since subtle olfactory cues (called pheromones) are known to mediate menstrual synchrony, write the authors, “this struck us as peculiar … because lesbians would be expected to be in closer, more intimate contact with one another on a daily basis than other females who live together. What is it about heterosexual females that promotes menstrual synchrony, or conversely what is it about lesbians that prevents menstrual synchrony? It occurred to us that one feature that distinguishes heterosexual women from lesbians is the presence or absence of semen in the female reproductive tract. Lesbians have semen-free sex.”
Perhaps you already see where this is leading. Gallup and Burch reasoned that certain chemicals in human semen, through vaginal absorption, affect female biology in such a way that women who have condom-less sex literally start to smell different from those women—lesbians or otherwise—who do not. At least, bodies of the former emit pheromones that “entrain” menstrual cycles among cohabiting women. (Their hunch was indeed borne out as they reviewed the existing literature on menstrual synchrony.) But this happenstance discovery of asynchronous lesbians was just the tip of the semen iceberg for Gallup and Burch, who quickly discovered that although much was known among biologists about basic semen chemistry, virtually nothing was known about precisely how these chemicals might influence female biology, behavior, and psychology.
And that is a rather odd omission in the biological literature indeed, since there could hardly be anything more obvious in Darwinian terms than the fact that semen is, almost by definition, naturally designed to get into the chemically absorptive vagina. Bear in mind that although they are often conflated in everyday parlance, along with many other less scientific terms, semen is not the same thing as sperm. In fact, you may be surprised to learn that only about 1 to 5 percent of the average human ejaculate consists of sperm cells. The rest of the ejaculate, once drained of these famously flagellating gametes, is referred to as “seminal plasma.” So when one discusses the chemical composition of semen, it is the plasma itself, not the spermatozoa, that is at issue.
Now, medical professionals have known for a very long time that the vagina is an ideal route for drug delivery. This is because the vagina is surrounded by an impressive vascular network. Arteries, blood vessels, and lymphatic vessels abound, and—unlike some other routes of drug administration—chemicals that are absorbed through the vaginal walls have an almost direct line to the body’s peripheral circulation system. So it makes infinite sense, argue Gallup and Burch, that like any artificially derived chemical substance inserted into the vagina via pessary, semen might also have certain chemical properties that tweak female biology.
It turns out that this insight, so obvious as to be all but invisible, has been a theoretical gold mine for this hawkeyed pair of adaptation-minded thinkers. But before we jump into their rich vat of seminal theory, let’s have a quick look at some of the key ingredients of human semen. In fact, semen has a very complicated chemical profile, containing more than fifty different compounds (including hormones, neurotransmitters, endorphins, and immunosuppressants), each with a special function and occurring in different concentrations within the seminal plasma. Perhaps the most striking of these compounds is the bundle of mood-enhancing chemicals in semen. There is good in this goo. Such anxiolytic chemicals include, but are by no means limited to, cortisol (known to increase affection), estrone (which elevates mood), prolactin (a natural antidepressant), oxytocin (also elevates mood), thyrotropin-releasing hormone (another antidepressant), melatonin (a sleep-inducing agent), and even serotonin (perhaps the best-known antidepressant neurotransmitter).
Given these ingredients—and this is just a small sample of the mind-altering “drugs” found in human semen—Gallup and Burch, along with the psychologist Steven Platek, hypothesized rather boldly that women having unprotected sex should be less depressed than suitable control participants. To investigate whether semen has antidepressant effects, the authors rounded up 293 college females from the SUNY Albany campus who agreed to fill out an anonymous questionnaire about various aspects of their sex lives. Recent sexual activity without condoms was used as an indirect measure of seminal plasma circulating in the woman’s body. Each participant also completed the Beck Depression Inventory, a commonly used clinical measure of depressive symptoms.
The most significant findings from this study, published with criminally modest fanfare in the Archives of Sexual Behavior, were these: even after adjusting for frequency of sexual intercourse, women who engaged in sex and “never” used condoms showed significantly fewer depressive symptoms than did those who “usually” or “always” used condoms. Importantly, these chronically condom-less, sexually active women also evidenced fewer depressive symptoms than did those who abstained from sex altogether. By contrast, sexually act
ive heterosexual women, even really promiscuous women, who used condoms were just as depressed as those practicing total abstinence. In other words, it’s not just that women who are having sex are simply happier, but happiness appears to be a function of the ambient seminal fluid pulsing through one’s veins.
Relax, settle down, take a deep breath—I know what you’re thinking. This is a correlation study, and there are scores of other possible causes and explanations, both those that the authors anticipated and controlled for in this study design (by all means read the original work for more details, but note that these between-group differences in depression panned out even after controlling for the use of oral contraceptives, days since last sex, frequency of sex, and duration of the relationship with the male partner) and probably some that you can come up with on your own. Even the authors urge some degree of skepticism: “It is important to acknowledge that these data are preliminary and correlational in nature, and as such are only suggestive. More definitive evidence for antidepressant effects of semen would require more direct manipulation of the presence of semen in the reproductive tract and, ideally, the measurement of seminal components in the recipient’s blood.”
Now, I’m hedging here, but one thing I do want to mention, with a helpful nod from the authors of this study, is that the antidepressant effects of seminal plasma may not be limited to vaginal absorption of its mood-brightening chemical properties. “It would be interesting to investigate,” write Gallup and his coauthors, “the possible antidepressant effects of oral ingestion of semen, or semen applied through anal intercourse (or both) among both heterosexual couples as well as homosexual males.”