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One reason why humans are special and unique: We masturbate. A lot

The views expressed are those of the author and are not necessarily those of Scientific American.

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There must be something in the water here in Lanesboro, Minnesota, because last night I dreamt of an encounter with a very muscular African-American centaur, an orgiastic experience with – gasp – drunken members of the opposite sex and (as if that weren’t enough) then being asked by my hostess to wear a white wedding dress while giving a scientific keynote presentation. “Does it make me look too feminine?” “Not at all,” she assured me, “it’s a man’s dress.”

Now Freud might raise his eyebrows at such a lurid dreamscape, but if these images represent my repressed sexual yearnings, then there’s a side of me that I apparently have yet to discover. But I doubt that this is the case. Dreams with erotic undertones are like most other dreams during REM sleep—runaway trains with a conductor who is helpless to do anything about the surrealistic directions they take. Rather, if you really want to know about a person’s hidden sexual desires, then find out what’s on his or her mind’s eye during the deepest throes of masturbation.

This conjuring ability to create fantasy scenes in our heads that literally bring us to orgasm when conveniently paired with our dexterous appendages is an evolutionary magic trick that I suspect is uniquely human. It requires a cognitive capacity called mental representation (an internal “re-presentation” of a previously experienced image or some other sensory input) that many evolutionary theorists believe is a relatively recent hominid innovation.

When it comes to sex, we put this capacity to very good—or at least, very frequent—use. In a now-classic, pre-Internet-porn (I’ll get to that later on) study by British evolutionary biologists Robin Baker and Mark Bellis, male university students were found to masturbate to ejaculation about every 72 hours, and “on the majority of occasions, their last masturbation is within 48 hours of their next in-pair copulation.” If they’re not having intercourse every day, that is to say, men tend to pleasure themselves to completion no more than two days prior to having actual sex.

Baker and Bellis’s quite logical argument for this seemingly counterintuitive state of affairs (after all, shouldn’t men try to stock up as much sperm as possible in their testes rather than spill their seeds so wastefully in a rather infertile swath of toilet paper or a dirty sock?) is that because there is a “shelf-life” for sperm cells – they remain viable for only 5-7 days after production – and because adult human males manufacture a whopping 3 million sperm per day, masturbation is an evolved strategy for shedding old sperm while making room for new, fitter sperm. It’s quality over quantity. Here are the adaptive logistics.

The advantage to the male could be that the younger sperm are more acceptable to the female and/or are better able to reach a secure position in the female tract. Moreover, once retained in the female tract, younger sperm could be more fertile in the absence of sperm competition [sexually monogamous relationships] and/or more competitive in the presence of sperm competition [in which the woman is having sex with other men]. Finally, if younger sperm live longer in the female tract, any enhanced fertility and competitiveness would also last longer.

Unconvinced? Well, Baker and Bellis are clever empiricists. They also apparently have stomachs of steel. One way that they tested their hypotheses was to ask over 30 brave heterosexual couples to provide them with some rather concrete samples of their sex lives: the vaginal “flowbacks” from their post-coital couplings, in which some portion of the male’s ejaculate is spontaneously rejected by the woman’s body.

The flowback emerges 5-120 min after copulation as a relatively discrete event over a period of 1-2 min in the form of three to eight white globules. With practice, females can recognize the sensation of the beginning of flowback and can collect the material by squatting over a 250 ml glass beaker. [And here comes a useful tip, ladies…] Once the flowback is nearly ready to emerge, it can be hastened by, for example, coughing.

As the authors predicted, the number of sperm in the girlfriends’ flowbacks increased significantly the longer it had been since the boyfriend’s last masturbation — even after the researchers controlled for the relative volume of seminal fluid emission as a function of time since last ejaculation (the longer it had been, the more ejaculate was present). If only the parents of teenage boys had these findings available for the first hundred thousand years of our history, think of all the anxiety, guilt and shame that might never have been.

In fact, even the father of adolescent psychology research, G. Stanley Hall, had a particularly nasty thorn in his paw when it came to the subject of masturbation. Hall accepted that spontaneous nocturnal emissions (that is, “wet dreams”) in adolescent boys were “natural,” but he viewed masturbation as a “scourge of the human race … destructive of that perhaps most important thing in the world, the potency of good heredity.” In Hall’s view, the offspring of teenage masturbators would show signs of “persistent infantalism or overripeness.” Boys will be boys, Stanley, and how wrong you were.  

Now back to masturbation fantasies and cognition—and this is where it gets really interesting. Baker and Bellis’s theory may be peculiarly true for human beings, because from all appearances, under natural conditions, we are the only primate species that seems to have taken these seminal shedding benefits into its own lascivious hands. Unfortunately, there have been a paltry handful of studies tracking the masturbatory behaviors of nonhuman primates. Although some relevant data is probably buried in some mountain of field notes, I didn’t come across any targeted studies on the subject in wild chimpanzees , and even the prolific Jane Goodall doesn’t seem to have ever gone there. But nevertheless by all available accounts, and by contrast with human beings, masturbation to completion is an exceedingly rare phenomenon in other species with capable hands very much like our own. As anybody who has ever been to the zoo knows, there’s no question that other primates play with their genitalia; the point is that these diddling episodes so seldom lead to an intentional orgasm.

In a 1983 study from the International Journal of Primatology , the sexual behaviors of several groups of wild gray-cheeked mangabeys were observed for over 22 months in the Kibale Forest of Western Uganda. There was plenty of sex, particularly during the females’ peak swellings. But just two incidents of male masturbation leading to ejaculation were observed. Yes, that’s right. Whereas healthy human males can’t seem to go without masturbating for longer than 72 hours, two measly cases of masturbating mangabeys were observed over a nearly two-year period.

University College London anthropologist E.D. Starin didn’t have much luck spying incidents of masturbation in red colobus monkeys in Gambia, either. In a brief 2004 article published in Folia Primatologica , Starin reports that over a 5.5-year period of accumulated observations totalling more than 9,500 hours, she saw only 5–count ‘em, five –incidents of her population of five male colobus monkeys masturbating to ejaculation, and these rare incidents occurred only when nearby sexually receptive females were exhibiting loud courtship displays and copulations with other males.

Intriguingly, Starin says that although females weren’t in the immediate vicinity, it is possible that the females could still be seen or heard by the masturbating male while the incident at hand occurred. (In other words, no mental representation required.) In fact, the author’s descriptions of these events strike me as producing accidental, rather than deliberate, ejaculations. Not that they weren’t happy accidents, but still. “During each observation,” Starin writes, “the male sat and rubbed, stretched, and scratched his penis until it became erect, after which additional rubbing produced ejaculate.” I know what you’re thinking: What did the monkeys do with the “product”? Well, they ate their own ejaculate—and in one case, a curious infant licked it off the adult’s fingers. Also, out of the 14 female colobus monkeys observed during this time span, “three different females were observed possibly masturbating” by self-stimulating their genitals—only possibly because none of these episodes culminated in the telltale signs of colobus orgasm: muscle contractions, facial expressions or calls.

Perhaps the most colorful report of nonhuman primate masturbation—or rather the astonishing lack thereof, even in subordinate males that aren’t getting any—comes from a 1914 Journal of Animal Behavior study by a primatological colleague of Robert Yerkes named Gilbert Van Tassel Hamilton, who apparently ran something of a monkey research center-cum-sanctuary on the lush grounds of his Montecito, California estate. Hamilton was clearly a pioneering sexologist, or at least had especially liberal attitudes for his time, defending the naturalness of homosexual behavior in the animal kingdom, among other things. In justifying his research, which meant getting up close and personal with his monkeys’ genitals, Hamilton opines:

The possibility that the types of sexual behavior to which the term ‘perverted’ is usually applied may be of normal manifestation and biologically appropriate somewhere in the phyletic scale has not be sufficiently explored.

In fact, he seems to have expected to find rampant masturbation in his animals, but to his surprise only one male (named Jocko) ever partook in such manual pleasures:

Of all my male monkeys only Jocko has been observed to masturbate. After a few days confinement he would masturbate and eat part of his semen. I have reason to believe that he lived under unnatural conditions for many years before I acquired him. In view of this fact that not one of seven sexually mature monkeys masturbated after several weeks of isolation under conditions that favored a fairly healthy mental and physical life (close proximity to other monkeys, large cage, warm climate) I am inclined to believe that masturbation is not of normal occurrence among monkeys.

Granted, Hamilton seems to have been a tad eccentric. Earlier in the article he reports that one of his female monkeys named “Maud” liked to be mounted (and entered) by a pet male dog out in the yard until one day poor, horny old Maud offered her backside to a strange mongrel that proceeded to bite off her arm. More disturbing is Hamilton’s description of a monkey named “Jimmy” who one sunny afternoon discovered a human infant lying in a hammock: “Jimmy promptly endeavoured to copulate with the infant,” observes Hamilton matter-of-factly. It’s unclear whether or not this was the author’s own child, nor is there any mention of the look on said human infant’s mother’s face when she saw what Jimmy was getting up to.

In any event, though he may have had some questionable child supervision skills, the candor by which Hamilton reports on the sex lives of his monkeys lends his non-observations of masturbation that much more credence.

So why don’t monkeys and apes masturbate even nearly as much as humans? It’s a rarity even among low status male nonhuman primates that frustratingly lack sexual access to females–in fact, the few observed incidents seem to be with dominant males. And why haven’t more researchers noticed such an obvious difference with potentially enormous significance for understanding the evolution of human sexuality? After all, it’s been nearly 60 years since Alfred Kinsey first reported that 92 percent of Americans were involved in masturbation leading to orgasm.

The answer for this cross-species difference, I’m convinced, lies in our uniquely evolved mental representational abilities—we alone have the power to conjure up at will erotic, orgasm-inducing scenes in our theater-like heads … internal, salacious fantasies completely disconnected from our immediate external realities. One early sex researcher, Wilhelm Stekel, described masturbation fantasies as a kind of trance or altered state of consciousness, “a sort of intoxication or ecstasy, during which the current moment disappears and the forbidden fantasy alone reigns supreme.”

Go on, put this article aside, take a five minute break and put my challenge to the test (don’t forget to close your office door if you’re reading this at work): Just try to masturbate successfully—that is, to orgasmic completion—without casting some erotic representational target in your mind’s eye. Instead, clear your mind entirely, or think of, I don’t know, an enormous blank canvass hanging in an art gallery. And of course no porn or helpful naked co-workers are permitted for this task either.

How’d it go? Do you see the impossibility of it? This is one of the reasons, incidentally, why I find it so hard to believe that self-proclaimed asexuals who admit to masturbating to orgasm are really and truly asexual. They must be picturing something , and whatever that something is gives away their sexuality.

Empirically capturing the phenomenology of masturbation fantasies is no easy matter. But some intrepid scholars have indeed tried to do so. A British physician named N. Lukianowicz, in a 1960 issue of the Archives of General Psychiatry , published one of the most sensational scientific reports I’ve ever had the pleasure of reading. Lukianowicz personally interviewed 188 people (126 males and 62 females) about their masturbation fantasies. An important caveat: all of these people were psychiatric patients with “various complaints and different neurotic manifestations,” so their masturbation fantasies aren’t necessarily typical. Nevertheless the details provided by these patients about their erotic fantasies give us an extraordinary glimpse into the rich internal imagery accompanying human masturbation. Consider the self-report of a retired civil servant, age 71, being treated for obsessive feelings of guilt on account of his “excessive masturbation”:    

I see in front of me naked beautiful women, dancing and performing some most exciting and tempting movements. After the dance they lean back, and keeping their legs wide apart, show their genitals and invite me to have sexual intercourse with them. They appear so real, that I can almost touch them. They’re in a setting of an oriental harem, in a large oval room with divans and a lot of cushions around the walls. I can clearly see the wonderful gorgeous colours and the beautiful patterns of the tapestry, with an unusual vividness and with all the minute details.

Or consider Lukianowicz’s account of a 44-year-old schoolmaster’s fantasies, which reads like some Bacchanalian, morphine-dappled scene ripped from the pages of William Burroughs’s Naked Lunch (1959):

In them he “saw” naked adolescent boys with their penes stiffly erected, parading in front of him. As he progressed in his masturbation, the penes of the boys increased in size, till finally the whole field of his vision was filled with one huge, erect, pulsating penis, and then the patient would have a prolonged orgasm. This type of homosexual masturbatory fantasy started shortly after his first homosexual experience, which he had had at the age of 10, and it persists unchanged hitherto.

Now, obviously, there are pathological cases of chronic masturbation where it actually interferes with the individual’s functioning. In fact, it’s not an uncommon problem for many caretakers of adolescent and adults with mental impairments, whose charges often enjoy masturbating in public and making onlookers squeal and squirm in discomfort. (Not unlike some captive primates housed in miserable conditions such as laboratories or roadside zoos, where self-stimulation sometimes becomes stereotypical.) But one thing that clinicians dealing with this problem may wish to consider is that the individual’s cognitive limitations may not allow them to engage in more “appropriate” private masturbation because of difficulties with mental representation. In fact, frequency of erotic fantasies correlates positively with intelligence. The average IQ of Lukianowicz’s sample was 132. So perhaps public masturbation, in which other people are physically present to induce arousal, is the only way that many with developmental disorders can achieve sexual satisfaction. Sadly, of course, society isn’t very accommodating of this particular problem: Between 1969-1989, for example, a single institution in the United States performed 656 castrations with the aim to stop the men from masturbating. One clinical study reported some success in eliminating this problem behavior by squirting lemon juice into the mouth of a young patient every time he pulled out his penis in public.

In any event, Lukianowicz argues that erotic fantasies involve imaginary companions not altogether unlike children’s make-believe friends. But unlike the more long-lived latter, he concedes, the former is conjured up for one very practical purpose: “… as soon as the orgasm is achieved the role of the imaginary sexual partner is completed, and he is quite simply and quickly dismissed from his master’s mind.”

And, perhaps not surprisingly, men seem to entertain more visitors in their heads than do women. In a 1990 study published in the Journal of Sex Research , evolutionary psychologists Bruce Ellis and Donald Symons found that 32 percent of men said that they’d had sexual encounters in their imagination with more than 1,000 different people, compared to only 8 percent of women. Men also reported rotating in from their imaginary rosters one imagined partner for another during the course of a single fantasy more often than women did.

In their excellent 1995 Psychological Bulletin article on sexual fantasy, University of Vermont psychologists Harold Leitenberg and Kris Henning summarize a number of interesting differences between the sexes in this area. In their review of research findings up to that date, the authors concluded that, in general, a higher percentage of men reported fantasizing during masturbation than did women. It’s important to point out, however, that neither “fantasy” nor “masturbation” were consistently defined across the studies summarized by Leitenberg and Henning, and some participants likely interpreted “masturbation” to mean simply self-stimulation (rather than orgasm-inducing ) or had a more elaborate conceptualization of “fantasy” than we’ve been using here, as some form of basic mental representation. For uncertain reasons, one dubious study compared “Blacks” and “Whites,” so it’s definitely a mixed bag in terms of empirical quality. They didn’t find much of a difference, by the way.

A side note: both sexes claimed equally to have used their imaginations during intercourse. Basically, at some point, everyone tends to imagine someone—or something—else when they’re having sex with their partner. There’s nothing like the question, “What are you thinking about?” to ruin the mood during passionate sex.

Here are some other interesting tidbits. Males report having sexual fantasies earlier in development (average age of onset 11.5 years) than do females (average age of onset 12.9 years). Females are more likely to say that their first sexual fantasies were triggered by a relationship, whereas males report having theirs triggered by a visual stimulus. For both men and women, straight or gay, the most common masturbation fantasies involve reliving an exciting sexual experience, imagining having sex with one’s current partner and imagining having sex with a new partner.

It gets more interesting, of course, once you step a little closer to the data. In one study with 141 married women, the most frequently reported fantasies included “being overpowered or forced to surrender,” and “pretending I am doing something wicked or forbidden.” Another study with 3,030 women revealed that “sex with a celebrity ,” “seducing a younger man or boy,” and “sex with an older man” were some of the more common themes. Men’s fantasies contain more visual and explicit anatomical detail (remember the giant, pulsating penis from Lukianowicz’s study?) whereas women’s involve more story line, emotions, affection, commitment and romance. Gay men’s sexual fantasies often include, among other things, “idyllic sexual encounters with unknown men,” “observing group sexual activity,” and here’s a shocker: images of penises and buttocks. According to one study, the top five lesbian fantasies are “forced sexual encounter,” “idyllic encounter with established partner,” “sexual encounters with men,” “recall of past gratifying sexual encounters,” and—ouch!—“sadistic imagery directed toward genitals of both men and women.”

One of the more intriguing things that Leitenberg and Henning conclude is that, contrary to common (and Freudian) belief, sexual fantasies are not simply the result of unsatisfied wishes or erotic deprivation:

Because people who are deprived of food tend to have more frequent daydreams about food, it might be expected that sexual deprivation would have the same effect on sexual thoughts. The little evidence that exists, however, suggests otherwise. Those with the most active sex lives seem to have the most sexual fantasies, and not vice versa. Several studies have shown that frequency of fantasy is positively correlated with masturbation frequency, intercourse frequency, number of lifetime sexual partners, and self-rated sex drive.

The Psychological Bulletin article on sexual fantasy is chockfull of interesting facts, and those with a more scholarly interest in this subject should read it themselves. Leitenberg and Henning also provide a fascinating discussion about the relation between sexual fantasy and criminality, including a clinical study in which deviant masturbatory fantasies were paired with the foul odor of valeric acid or rotting tissue. Now that’s enough to put a crimp in anybody’s libido, I’d say. But Leitenberg and Henning’s piece was written over fifteen years ago, summarizing even older research. The reason this is important is because it was still long before the “mainstreaming” of today’s Internet pornography scene, where zero is left to the imagination.

And so I’m left wondering … in a world where sexual fantasy in the form of mental representation has become obsolete, where hallucinatory images of dancing genitalia, lusty lesbians and sadomasochistic strangers have been replaced by a veritable online smorgasbord of real people doing things our grandparents couldn’t have dreamt up even in their wettest of dreams, where randy teenagers no longer close their eyes and lose themselves to the oblivion and bliss but instead crack open their thousand-dollar laptops and conjure up a real live porn actress, what, in a general sense, are the consequences of liquidating our erotic mental representational skills for our species’ sexuality? Is the next generation going to be so intellectually lazy in their sexual fantasies that their creativity in other domains is also affected? Will their marriages be more likely to end because they lack the representational experience and masturbatory fantasy training to picture their husbands and wives during intercourse as the person or thing they really desire?

I’m not saying porn isn’t progress, but I do think that over the long run it could turn out to be a real evolutionary game-changer.

In this column presented by Scientific American Mind magazine, research psychologist Jesse Bering of Queen’s University Belfast ponders some of the more obscure aspects of everyday human behavior. Sign up for the RSS feed, visit, friend Dr. Bering on Facebook or follow @JesseBering on Twitter and never miss an installment again. For articles published prior to September 29, 2009, click here: older Bering in Mind columns. Jesse’s first book, The Belief Instinct (Norton) [The God Instinct (Nicholas Brealey) in the U.K.], will be published early February, 2011.

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  1. 1. GitMoe 12:56 pm 06/23/2010

    Me: Female, mid twenties. Used to masturbate daily. Now, not so much.

    But, I must say, I don’t need to think about a damn thing to reach orgasm. Sure, it’s fun sometimes, but often I just do it to do it.

    Case in point: Two orgasms today while driving on the freeway. Obviously my main focus was watching the road. No fantasty involved and fairly easy too; I can reach orgasm in under a minute.

    At home, I find that I reach orgasm FASTER if I think of absolutely nothing and just leave my mind a blank. It takes much longer if I start fantasizing my way through "the roster." For a quick morning pick-me-up before getting out of bed, I prefer the mind-blank orgasm, start to finish between a snooze setting on my alarm.

    In general, I’m a much happier person if I masturbate frequently. If I abstain for a couple of weeks, I inevitably have dream orgasms – the equivalent of a male wet dream, without the mess.

    It would sure be great if I could help scientific research by making it my job to masturbate. For science! Yes!

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  2. 2. FBK 1:08 pm 06/23/2010

    I hear ya and re:posted it.

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  3. 3. FBK 1:10 pm 06/23/2010

    Nice article. Masturbate often!

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  4. 4. turtlecrk 2:55 pm 06/23/2010

    Years ago I kept goats. Males masterbate several times a day, except during the breeding season when it’s several times an hour. There were occasional problems with diaper rash on the backs of their front legs, from the constant semen splash.

    Maybe they have an active fantasy life, but I’d suspect that there is a more biological reason for the differences between species.

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  5. 5. korax 3:16 pm 06/23/2010

    Hmm…why aren’t bonobos, the most sexual of the great apes, mentioned in this article? Frans de Waal mentions here that bonobos masturbate frequently and (at least in females) probably to orgasm.

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  6. 6. mbdsta 3:17 pm 06/23/2010

    Two comments…

    1) do we really need an article this long on masturbation? I almost had to go rub one out just to take the pain of reading this away.

    2) I’ve never heard masturbation called an "evolutionary magic trick" but I kind of like that, I’m going to have to work that into the lexicon…I can see it now– LadyFriend: "Hey, what are you up to tonight?" Me: "Magic."

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  7. 7. korax 3:18 pm 06/23/2010

    Hmmm, curious that bonobos, the most sexual of the great apes are not referenced here. Frans de Waal mentions here that bonobos frequently masturbate and, at least in females, probably to orgasm.

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  8. 8. Roquelaure 6:11 pm 06/23/2010

    I find the absence of discussion of bonobo chimps to be so glaring as to undermine the article as a whole. Can you even Google "monkey" or "primate" and "masturbation" without getting a million hits re: bonobos? How could this possibly been left out if not for the obvious reason that it utterly subverts the author’s thesis?

    It’s a shame because there’s a lot of interesting food for thought here in regards to animals and humans, and the mechanisms for masturbation, and in my mind at least, no reason to gloss over the overlapping species. Humans don’t have to be unique to be interesting.

    The article falls further with utterly rote summaries of gender differences re: sexual fantasies. Perhaps that has to do with the outdated source material. I have the greatest esteem for Psychological Bulletin – but has there really not been a single respectable article published on this since 1995? I felt I may as well been reading the prevailing opinion of 1965. The author wonders if the intervening years and the advent of the internet have made a major difference on sexual fantasies. Yes, that would be interesting to know, wouldn’t it?

    Or the study on the sexual fantasies of psychiatric patients. The author, commendably, notes this limitation in the article, but I’d say the mental stability of the subjects is a pretty gigantic caveat, or at least a mortal blow to the generalization of the findings. And again, I’m sure there’s more recent and germane information on this topic to be discussed. Perhaps it makes for too boring of a narrative.

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  9. 9. Urinal Gum 6:40 pm 06/23/2010

    Dammit! They need to do some useful research! Like, why won’t my wife let me masturbate in peace? She’s always interrupting and trying to see what is on the computer screen before I can shut the thing down!

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  10. 10. jack.123 8:57 pm 06/23/2010

    Having read the article and comments I can tell that none or most didn’t grow up on a farm, or have visited a zoo very often.where animal masturbation is a frequent sight.And when at the zoo, when primates are throwing excrement at you, turn away,because eye infections can result in a trip to the hospital and or can result in death.But don’t take it personally as primates do this as a defense against predators who are looking at them.As for male humans where rape is frowned upon,females often withhold sex using it as a tool to get what they want thus leading males to do what they do,as for females it may many times be that masterbation is used as prevention of pregnancy.wherein sexual intercourse is almost always available for the asking.

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  11. 11. guangtouge 11:33 pm 06/23/2010


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  12. 12. suresh10in 12:26 am 06/24/2010

    Many animals do masturbate to completion like elephants and some birds ,and in ayurveda there are preparations of herbominerals which use such seminal emissions ,which in some cases linger longer on tree barks and rocks like some exudate ,and have to be scrapped off.Of course man may have to capacity to linger longer with his imagery while masturbating ,and that is because of the mental capacity or space to hold more images in mind than animals ,and that is a measure of his intelligence,and emotional make-up.This imagery is what contributes to self system,and that is why masturbation is associated with certain psychological aspects ,in neurotic subjects.
    The physical act of masturbation is itself sufficient to produce and ejection or orgasm ,and man does not differ there much from animals.Of course some mental involvement may be more due to innate structures in humans as compared to animals.The biological need for masturbation apart ,there is psychological aspect to it ,which is true for some animals like elephants which go mad and behave anomalously while being in heat and not having rubbed their organ to completion of the masturbatory act on some hard substance.

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  13. 13. Elizabeth L 1:02 am 06/24/2010

    A really important question is missing from the research you cited: what evolutionary purpose does FEMALE MASTURBATION serve? The study had a good theory for male masturbation- fresher sperm are less likely to be rejected. Why haven’t scientists studied the other side of the coin? There must be some kind of bias there.

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  14. 14. jgrosay 2:31 am 06/24/2010

    A Barcelona based psychiatrist called masturbation "Auto chiro erastia", some kind of a handy substitute for homoxseual sex. Besides that if it is not so, surely it opens such kind of homo or impersonal sex drive discharge, masturbation is also an insult to dozens of women and men that want a real relationship with the solo-ipsists. Even more, it’s clearly a deadly sin, better look for a more altruist kind of satisfaction. A spanish joke said: what do you prefer: masturbating or fucking? -answer: let me check… I would prefer fucking. Yes, but why? – Well, you meet people…

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  15. 15. hawkeye 2:56 am 06/24/2010

    There was a young man from Peru

    Who fell asleep while in a canoe.

    While dreaming of Venus

    He played with his penis

    And woke up with a handful of goo.

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  16. 16. dudeinhammock 6:35 am 06/24/2010

    "Between 1969-1989, for example, a single institution in the United States performed 656 castrations with the aim to stop the men from masturbating."

    Are you sure you’ve got the century right on this? If so, how about a reference? Thanks.

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  17. 17. akj84 5:19 pm 06/25/2010

    If males benefit from masturbation in evolutionary terms…is there any benefit for females? Why do women masturbate since there is no "shedding of old sperm" in female masturbation? I think female masturbation is greatly overlooked. You could make the argument that women don’t masturbate as often as men, which might be true, but there are definitely a LOT of women out there who masturbate (whether regularly or not) who just don’t talk about it.

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  18. 18. hellblade 6:06 pm 06/25/2010

    "The Psychological Bulletin article on sexual fantasy is chockfull of interesting facts"

    i’m so glad this sentence was not misspelled.

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  19. 19. 2:39 am 06/28/2010

    Hello? Women masturbate too.

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  20. 20. Koltrast 2:11 pm 06/28/2010

    One reason why humans are special and unique: We masturbate. A lot….

    Hello! There is no reason for "why" after reason in the above sentence. How about studying the science of grammar?

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  21. 21. meghanelaine 3:05 pm 06/28/2010

    I know you were looking for studies that came about before the internet made porn a click away for millions of people but the facts exist: some people don’t like porn and/or there is no porn made for them (lesbians, for example — "lesbian" porn, have you seen it lately? femmes and more femmes, and sometimes there’s even a guy in there). Your remark about asexuals is extremely insensitive… I don’t see where it’s your place to say whether or not someone is "truly" asexual. If a person doesn’t aspire to sexual contact, that person may choose to label hirself asexual regardless of who or what they think about while masturbating.

    Anyway aside from that I think it was an interesting read, quite thought provoking, actually. Although I was a bit troubled by some of the language used. I mean I see no reason why men should just "naturally" be more inclined to have sexual fantasies than women — these studies are quite old and social attitudes play a big role in people’s responses when asked a question like, "How often do you masturbate?" or even how often they DO masturbate. If women are told always, "women don’t masturbate as much as men" guess what will happen?

    I’m just saying, these things are being cited as if they’re completely and emperically correct, when the world has changed and is changing since these studies were conducted.

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  22. 22. meghanelaine 3:08 pm 06/28/2010

    Thank you!

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  23. 23. meghanelaine 3:11 pm 06/28/2010

    Not to mention I was a little bit squicked out by the top lesbian fantasies — "sexual encounters with men" really? I think this study was done when a lot of women were identifying as lesbians politically. Shows you what citing a 15-year-old study will get you. Haven’t there been any recent studies you could have cited? At least give us some perspective as far as where we are now.

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  24. 24. This is a one time thing 5:36 pm 06/28/2010

    What if I usually think of sexual imagery for the first orgasm, but then continue on to several others while letting my mind wander over totally non-sexual imagery? Maybe its a female thing.

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  25. 25. This is a one time thing 5:40 pm 06/28/2010

    <i>"There are many examples of animals self-pleasuring to orgasm (who hasn’t witnessed a dog becoming over-romantic with a leg/table ?"</i>

    Er, I haven’t witnessed it "to completion". That sounds pretty disgusting, I think I would have noticed. But maybe other people have seen that…?

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  26. 26. kulibali 6:32 pm 06/28/2010

    Primates do in fact masturbate to orgasm.

    "Self-stimulation of the genitalia, equivalent to human masturbation, has been reported for a number of wild primates, especially amongst Old World monkeys and apes (see list in Dixson [1998]). While it is neither simply a by-product of captivity [Thomsen et al., in press] nor solely explicable as a substitute for copulation [Dixson, 1998], since wild monkeys and apes masturbate even when females are available, the functional significance of masturbation remains obscure. Baker and Bellis [1993, 1995] have suggested that masturbation is a reproductive strategy whereby low-quality sperm is flushed out of the system, thus increasing the quality of the next ejaculate which then should outcompete older sperm from rivals during sperm competition. In short, it has been suggested that well-timed masturbation may be part of the primate male’s reproductive strategy, by which ejaculates are optimised with respect to their ability to fertilise ova in a sperm competition game with rival males [Thomsen et al., in press]."

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  27. 27. a44 8:11 am 06/29/2010

    "Monkey research center-cum-sanctuary"
    I see what you did there.

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  28. 28. eyespot 5:18 pm 06/29/2010

    My head is reeling… what a fun article, for the most part… (except the part about the castrations… please tell me that it is not permissible to mutilate people simply to prevent them from masturbating in public… is America *this* disgusted with such a benign activity? I see kids making out all the time in public… adults also–shall we start cutting off lips and so forth… *deep cleaning breath*)

    In any case… my favourite part was "masturbatory fantasy training" lololol… no trouble filling up that course I would imagine.

    Probably could have done without the knowledge of the "dirty sock" trick… (as a mother/wife who does laundry)

    One quibble… I’m not sure that what women picture during masturbation " gives away their sexuality" as Jesse suggests. Wasn’t there some recent Northwestern study that showed that women’s arousal patterns don’t really map to orientation?…. let me dig it up.. one sec (and no, I’m not going to masturbate while I’m gone)….

    I guess it is not that recent but nonetheless… (I think
    J. Michael Bailey has a number of interesting orientation papers.)

    Though perhaps arousal during visual imagery exposure is not the same as a *specifically* chosen fantasy. Dunno.

    Anyway, great article…

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  29. 29. eyespot 5:20 pm 06/29/2010

    My head is reeling… what a fun article, for the most part… (except the part about the castrations… please tell me that it is not permissible to mutilate people simply to prevent them from masturbating in public… is America *this* disgusted with such a benign activity? I see kids making out all the time in public… adults also–shall we start cutting off lips and so forth… *deep cleaning breath*)

    In any case… my favourite part was "masturbatory fantasy training" lololol… no trouble filling up that course I would imagine.

    Probably could have done without the knowledge of the "dirty sock" trick… (as a mother/wife who does laundry)

    One quibble… I’m not sure that what women picture during masturbation " gives away their sexuality" as Jesse suggests. Wasn’t there some recent Northwestern study that showed that women’s arousal patterns don’t really map to orientation?…. let me dig it up.. one sec (and no, I’m not going to masturbate while I’m gone)….

    I guess it is not that recent but nonetheless… (I think
    J. Michael Bailey has a number of interesting orientation papers.)

    Though perhaps arousal during visual imagery exposure is not the same as a *specifically* chosen fantasy. Dunno.

    Anyway, great article…

    Link to this
  30. 30. 3PP 6:15 pm 06/29/2010

    Julie Vern,

    I’m a 30 year old straight male and I accomplished the task, as well. Although, at the 5 minute mark, I was only about 2/3 of the way through.

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  31. 31. thales 2:39 am 06/30/2010

    Jesus masturbated.

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  32. 32. qraal 5:32 am 06/30/2010

    As a wise man once said, Masturbation can be safe, fun, hygienic, cheap… but lonely. Fantasy never substitutes for reality, though squishy, messy "virtual reality" via Net-porn is kind of off-putting IMO.

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  33. 33. tichead 11:37 am 06/30/2010

    Sign me up for the next study! On second thought, "Not tonight dear, I had a long, hard day at the office and I’m just not up to it.", could ruin a relationship in short order. OK, I’ll pass on being a subject in the next study. Fantasy is fun, but reality is way more exciting.

    I couldn’t agree more with the comments about the total absence of reference to bonobo chimp behavior and minimal reference to female behavior. A serious oversight inconsistent with SciAm’s usual high level of thoroughness. Perhaps Jesse Bering and the editor were too distracted by their own fantasies.

    I understand the one premise of the article is the potential competitive advantage of young sperm. However, the disturbing implication of the main premise, that fantasy visualization provides H. sapiens with some sort of evolutionary advantage, is that females are less evolved than males because they are less likely to use such mental imagery to achieve orgasm from masterbation. So, I suspect that premise is flawed.

    @thales: "Jesus masterbated." Would that be a ‘mis-conception’? So much for the second coming. Oh, to be touched by the hand of… And, he was HEALED!! Sorry, I was getting a getting a bit carried away by my mental imagery there.

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  34. 34. c.harvey 7:58 pm 06/30/2010

    On the bonobo stuff, there’s maybe some passing references out there on it, but I seriously doubt anyone has ever done any studies on bonobo masturbation specifically, so what’s he supposed to talk about? My guess is that, like Bering says, it would be rare to see a male bonobo jacking off to completion. Maybe they play with themselves more than other primates do, and once in a while they even ejaculate, but still nowhere near as much as people do.

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  35. 35. Dwergmal 8:31 am 07/1/2010

    I believe your misinterpretation was addresses in the article. He stated that One of the more frequent monkey masturbators had come from a bad situation. Clearly the animals you are referring to are in abberrant situations and would not have the same responses as a wild individual. Also, rape as we know it in human society is relatively rare in the animal kingdom.

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  36. 36. sunspot 8:26 pm 07/1/2010

    While the article is too lengthy and rambling to finish, I expected some early and frequent references to addiction to sexual stimulation by oversexed humans who, like the author, attribute far too much importance to sexual acts and needs.

    In the wild, mating is not often without severe risks, and frequent risk is usually fatal. The more balanced view of wild animals may not be so much the availability of frequent sex, but merely the acknowledgement of attendant risk, not unrelated to the act of rape by humans. If humans, like bonobo monkeys, used sex to quell aggressive behavior, the result would probably be mass human extinction fron STDs.

    It may be an evolutionarily beneficial behavior of humans to socially repress such irresponsible fatherhood in order to improve chances of survival by isolating diseases to social misfits who try to spread them promiscuously for selfish reasons or due to compulsive pleasure addiction.

    One does wonder why such a flawed and slanted monologue belongs on a reputable website instead of a salacious blog which could be blocked by responsible parties due to the obviously explicit content, reveled in by the author, who attempts to justify this burst of mental self-gratification by occasional references to so-called "studies". How far will SciAm go in its slide into this psuedoscientific muckhole? This diatribe belongs on a bathroom wall.

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  37. 37. ttongmd 1:38 pm 07/2/2010

    I’ve seen a rhesus monkey masturbate

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  38. 38. Nox 11:28 pm 07/3/2010

    I am asexual. My mind is blank when I masturbate, which is not often.
    Imagining sexual acts would do nothing for me, seeing as I’m not sexually attracted to either gender.
    And many asexuals do have a sex drive…the only thing they lack is a sexual attraction toward men or women.

    Please do a little more research before making these comments about an orientation you likely don’t fully understand.

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  39. 39. c.harvey 5:24 am 07/4/2010

    @Nox: What does a "blank" mind look like, exactly? I think it’s fair to say that Bering has done his background reading on asexuality research. He wrote an entire article about it here:

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  40. 40. ImproperUsername 1:16 pm 07/5/2010

    Something that I would like to know is, since men are almost always thinking about sex, HOW is it that they have managed to accomplish so much? You know, stuff like building cities, running businesses, writing books, etc.

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  41. 41. Ramil 1:47 pm 07/5/2010

    Having personally lived for a long time with a (now deceased) non-neutered male cat who was free to go outside as often as he liked, I think it is relevant that this cat had a favorite blanket which he would frequently use to masturbate "to completion," while holding the blanket in his teeth, in the approved posture for mating with a female cat. Not realizing at the time that this was a scientifically important event, I did not document the frequency or duration of the events, but it seems fairly clear, in an intuitive sense, that this cat was "thinking" about a feline companion. It has been well documented that dogs and cats dream (as indicated by REM sleep and appropriate gestures and sounds while they’re sleeping), although I don’t have any journal references at hand, so why could they not imagine that they were mating with another cat? As other commentators on this article have noted, masturbation is common in the animal kingdom, so why assume that humans are special just because we do it more frequently than monkeys, who may have more urgent concerns, like avoiding getting eaten by a predator or finding food? After all, how many non-institutionalized humans take time off to masturbate while preparing for an important presentation or trying to meet a deadline for a journal article (even one on masturbation). Perhaps we should check this guy’s journal articles with a UV light.

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  42. 42. Dr. Desoto 6:54 pm 07/5/2010

    It seems to happen very naturally for me if I just concentrate on the growing sensation of pleasure, without any other thoughts. So, ditto!

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  43. 43. fixerdave 9:17 pm 07/6/2010

    I dunno, maybe it’s a wild verses domesticated thing, but I’ve seen a friend’s dog masturbate – yes, to completion – oh, about 5 times an hour with its favourite teddy bear. No idea what the dog was thinking. Yes, the bear was totally disgusting. As the dog occasionally worked for $600 per pop on stud fees, that teddy was probably worth serious coin.

    Again, maybe it’s just a screwed-up domesticated animal and not something that would happen in a natural habitat. But, then you could probably extrapolate that to humans. How many times would we be masturbating, to completion, if we didn’t exist in such a screwed-up society?

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  44. 44. Grant217 3:41 am 07/13/2010

    When I transitioned from female to male and started testosterone therapy, my entire fantasy life changed as well. I used to read erotic fiction to get me going, and it took forever to get off. Now all I have to do is look at one single image to get me going, ride along and complete – just one image! It’s amazing how hormones can completely change one’s sexual world. Just thought I’d share.

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  45. 45. c.harvey 10:51 am 07/16/2010

    @capriracer351: "It is ok to do an entire article on homosexual masturbation, but it is not ok to state the obvious…. That you are deviants."

    What? Huh? How on earth did you get that out of this article? Did you even read it?

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  46. 46. chenchen21621 10:19 pm 07/20/2010

    I always knew I was special, but I didn’t know that (I) am the most special person on earth. I always wondered how that ton of grease I invested in when I was a child would pay off…cool!!!!

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  47. 47. chenchen21621 10:20 pm 07/20/2010

    I just read this part and I haven’t even finished the entire article but I have to comment. Am I the only one who easily masturbates to orgasm without thinking sexual thoughts?

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  48. 48. si 6:33 am 08/12/2010


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  49. 49. si 6:33 am 08/12/2010


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  50. 50. daytonvh 11:43 pm 09/19/2010

    "If human males are in a situation where they can have sex anytime … they wouldn’t masturbate"

    I beg to differ; many people continue masturbating even with an available and enthusiastic partner, because often masturbation is a quick and expedient release when one doesn’t necessarily feel like tending to one’s partner’s needs as well. And what of couples who masturbate together?

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  51. 51. dombones2000 2:36 am 10/13/2011

    Aside from the fact that I may never be able to eat again after reading this article, I wonder; who does your laundry? I would hate to run into one of those old socks you use to masturbate in!

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  52. 52. Leeloominaï 1:16 pm 04/19/2012

    Just read this article, and I should have read the comments first. Used to work at a Zoo, and have raised many animals in my life. Most of my experience is with mammals; they all mastuebate, a lot. I remember female lemurs would back up to sticks within their enclosures and use them like dildos. You could tell which sticks because they were highly polished from consistant use. The great apes would masterbate any time they were bored, and the rabbits were very friendly with their bedding. All the critters did it, more than most people I know.

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  53. 53. Ceadaoin 8:50 pm 12/6/2013

    (Over)Long story short: If the research question is, Why do human males wank more than any other creature, and TONS of anecdotal evidence suggests it ain’t necessarily so, I guess it’s back to the drawing board?

    PS: Sticks? Ouch!


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