This “semen displacement theory” is the most intriguing part of Gallup’s story. We may prefer to regard our species as being blissfully monogamous, but the truth is that, historically, at least some degree of fooling around has been our modus operandi for at least as long we’ve been on two legs. Since sperm cells can survive in a woman’s cervical mucus for up to several days, this means that if she has more than one male sexual partner over this period of time, say within 48 hours, then the sperm of these two men are competing for reproductive access to her ovum. According to Gallup and Burch, “examples include, group sex, gang rape, promiscuity, prostitution, and resident male insistence on sex in response to suspected infidelity.” The authors also cite the well-documented cases of human heteroparity, where “fraternal twins” are in fact sired by two different fathers who had sex with the mother within close succession to each other, as evidence of such sexual inclinations.
So how did natural selection equip men to solve the adaptive problem of other men impregnating their sexual partners? The answer, according to Gallup, is their penises were sculpted in such a way that the organ would effectively displace the semen of competitors from their partner’s vagina, a well-synchronized effect facilitated by the “upsuck” of thrusting during intercourse. Specifically, the coronal ridge offers a special removal service by expunging foreign sperm. According to this analysis, the effect of thrusting would be to draw other men’s sperm away from the cervix and back around the glans, thus “scooping out” the semen deposited by a sexual rival.
You might think that’s fine and dandy, but one couldn’t possibly prove such a thing. But you’d be underestimating Gallup, who in addition to being a brilliant evolutionary theorist, happens also to be a very talented experimental researcher (among other things, he’s also well-known for developing the famous mirror self-recognition test for use with chimpanzees back in the early 1970s). In a series of studies published in a 2003 issue of the journal Evolution & Human Behavior, Gallup and a team of his students put the “semen displacement hypothesis” to the test using artificial genitalia of different shapes and sizes. They even concocted several batches of realistic seminal fluid. Findings from the study may not have “proved” the semen displacement hypothesis, but it certainly confirmed its principal points and made a believer out of most readers.
Here’s how the basic study design worked. (And perhaps I ought to preempt the usual refrain by pointing out firstly that, yes, Gallup and his co-authors did receive full ethical approval from their university to conduct this study.) The researchers selected several sets of prosthetic genitals from erotic novelty stores, including a realistic latex vagina sold as a masturbation pal for lonely straight men and tied off at one end to prevent leakage, and three artificial phalluses. The first latex phallus was 6.1 inches long and 1.3 inches in diameter with a coronal ridge extending approximately 0.20 inch from the shaft. The second phallus was the same length, but its coronal ridge extended only 0.12 inch from the shaft. Finally, the third phallus matched the other two in length, but lacked a coronal ridge entirely. In other words, whereas the first two phalluses closely resembled an actual human penis, varying only in the coronal ridge properties, the third (the control phallus) was the bland and headless horseman of the bunch.
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146 Comments
Add Commentsince maximum diversity is an imperative of the natural world it is highly unlikely humans are genetically predisposed to monogamy. perhaps that's why my lady friend, on awakening, stretches, then smiles and says,
Reply | Report Abuse | Link to this"i feel like a new man."
Phylogenetic continuity requires a limitation on expression of diversity. I would say that it's a balancing act. With respect to human mating, humans must transmit culture (as a primary survival tactic and phenotype), and therefore cooperative (ie: cheating/competing limiting) behaviour in mating is important. The cheater literally is a cheater. You're right, she does feel like a new man - it's a joke, right? Many a true thing said in jest? :D
Reply | Report Abuse | Link to thisPhylogenetic continuity requires a limitation on expression of diversity. I would say that it's a balancing act. With respect to human mating, humans must transmit culture (as a primary survival tactic and phenotype), and therefore cooperative (ie: cheating/competing limiting) behaviour in mating is important. The cheater literally is a cheater. You're right, she does feel like a new man - it's a joke, right? Many a true thing said in jest? :D
Reply | Report Abuse | Link to thisThe conclusion seems to be that gang rape (or polygamy within 48 hours) occurred often enough to have effected the course of evolution. This may coincide with the thousands of years when it was "normal" for one tribe to invade another, kill the men and children, and gang rape the women. In such an environment, the shape of the phallus today seems almost plausible.
Reply | Report Abuse | Link to thisWe need to hear an explanation now for the human female genital configuration.
Reply | Report Abuse | Link to thisWhile the semen-extractor explanation makes sense, I have to wonder if there isn't a sexual selection force at work as well. It is well known that humans indulge in rather a lot of oral-genital contact. Perhaps there are some clues in the innervation patterns, as they seem like more than coincidence. (I hope I am not being too obscure!)
Perhaps Jesse would like to comment on that angle???
Hmmm...! From my point of view, this is all I've been waiting for all my life. "A scientific reason (excuse) for cheating".
Reply | Report Abuse | Link to thisA pitty my wife would not understand it that way.... or perhaps use it on her own benefit.
Excellent article, Jesse. I couldn't stop laughing.
Reply | Report Abuse | Link to thisThis is all quite interesting, but it sounds identical to what it presented in Sperm Wars (Robin Baker) which was first published in 1996. Is this just a confirmation of that work, or does it differ?
Reply | Report Abuse | Link to thisMore so than for the semen displacement reason, the shape might have to do with the ability to create some degree of a vacuum. If there is some suction effect created by the shape of the phallus, even in a monogamous relationship, it might assist sealing the vaginal entry to some degree, at least for a certain time, giving the insemination a better chance of success.
Reply | Report Abuse | Link to thisAnother evolutionary 'just-so' story! Are you seriously suggesting that chimpanzees aren't promiscuous? Yet they lack this design feature. The hypothesis is fatally shot through from the get-go. There is an observed difference between the species, but this hypothesis, however cunning, does not explain it.
Reply | Report Abuse | Link to thisAnother evolutionary 'just-so' story! Are you seriously suggesting that chimpanzees aren't promiscuous? Yet they lack this design feature. The hypothesis is fatally shot through from the get-go. There is an observed difference between the species, but this hypothesis, however cunning, does not explain it.
Reply | Report Abuse | Link to thisI couldn't stop the random fits of bahaha-ing that came from the use of the term 'Rosetta Stone' for what seems like no apparent reason, coupled as it is with the absolute inanity of the penis-size phenomena.
Reply | Report Abuse | Link to thisThen again, I suppose girls could be laughed at just as much for jeeringly comparing breast size when those first started to develop.
Still, I notice the only guys who really care about the Mighty Sword are homosexuals, at least when it comes to it being a source of attraction. This isn't an incindiary statement, it's a matter of simple observation. That having been said--
There's women who can take more than others, as it were. 'One size fits all' is not the case on either side of the fence, which is certainly something else to consider.
'Up to two feet' if not contained. Uh, were you ever a teenager?
Reply | Report Abuse | Link to thisAfter looking at this matter for over 20 years, Im pretty much convinced that the physiology community have got at least part of it backward. Histologically and neurologically, the most specialised and evolved part of the male penis is the foreskin, which contains far more fine-touch receptors than the relatively dumb glans penis. It seems obvious that the latter is designed to aid insertion; it very well could have a useful scoop effect as described in this study; but its quite unlikely that it was ever a primary pleasure zone.
Reply | Report Abuse | Link to thisRelatively more of the research in this area of penile function seems to come from countries that routinely modified the penis (US, Canada, Australia) and so miss an obvious other answer. The glans has a specialized shape that marvelously stimulates the highly innervated inner foreskin, particularly one that is naturally snug as it slides back and forth during coitus. This would encourage more thrusting, especially to the point that the ridged band of innervated cells falls into formation at full preputial retraction when held by the frenulum. It is at this point, as described by Dr John Taylor in the BJU, that the male starts a steady climb to climax and the natural ejaculatory reflex begins. Along the way, at full ridged band and full thrust, the male collects sperm both behind the glans and in the preputial ridged band, as well as to either side of the frenulum as mentioned here. And the stimulation from the corona on both the vaginal wall and the male partners own deeply pleasurable inner foreskin makes for a decidedly different image. The glans then is not the most responsive member of the sex act, but rather the rock against which you wash the clothes , if you will. At rest, its more of a shoe tree. In an important sense, then, the glans is shaped the way it is to keep the prepuce well-formed, healthy and stimulated. And lest one think the foreskin is vestigial, research (such as that of Dr Chris Cold at the Marshfield Clinic) suggests that the foreskin of human males has in fact been growing longer and more innervated over the millennia.
Modern-day circumcision often reduces the coronal ridge flare , particularly in those hospital neonatal circumcisions which pull the shaft skin very tight, as has been more the norm in the US than elsewhere. Of course, this disadvantage is less obvious to those tribes which dont directly compete with invaders for their womens cervixes.
5 inches circmpherence? That's the landing wheel of an aircraft
Reply | Report Abuse | Link to thisThis is really interesting. I would like to request a similar article about the vagina.
Reply | Report Abuse | Link to thisWhile the argument presented seems plausible, why is it valid only for humans? It seems to me that animals are likely to have sex with multiple partners more frequently than humans, and you would therefore expect the evolutionary pressure on penis shape to be stronger in, say, chimps than in humans.
Reply | Report Abuse | Link to this"Well -maybe they didn't have the Gene Mutation for a bulboous penis" (although my dog -a real busy character did)
Reply | Report Abuse | Link to thisOr maybe the chimpanzee is such a co-operative guy that it's more important for his survival for his friends to impregnate his girl"
I wonder what a bonobo male is like? Bering?
There is one very true thing about our story here -sex is definitely a social activity mentally and physically beyond compare! And has shaped us and our society more than any other Mode. AND WE ARE THE MASTERS AMONG CREATURES.
Reply | Report Abuse | Link to thisThe penis was made to 'snap' into place against the cervix of the downturned uterus when mounting the woman from behind as we evolved. this delivers maximum sperm into the uterus.
Reply | Report Abuse | Link to thisFantastic article--very interesting hypotheses on rationale behind the shape and size of the penis. I learned much.
Reply | Report Abuse | Link to thisHowever, Jesse, you should be writing for Jon Stewart--not SA. You are a very funny guy! Well done!
LOL. The irony of a gay guy presenting a unidimensional discussion on why the phallus evolved into it's current shape... is sublime!
Reply | Report Abuse | Link to thisMine sockets just fine any-old-way.
Reply | Report Abuse | Link to thisI think it's curious that the Semen Displacement Theory is being presented as the major cause of penis evolution. Humans trend toward intelligence, and towards love, as much as violence. I know evolution doesn't care whether I "like it" or not, but I really just feel like the scenarios that are being presented are like a bukkake porn or something, where a woman is just covered in different men's sperm all the time, that women were just always available for men. Is it true? Do we know this?
Reply | Report Abuse | Link to thisYes a man can force a woman to have sex, but he cannot force genuine affection from her, and attachment is a fundamental human need - not just something for "sensitive" men. Why is the bulbous head not thought to have evolved because it deepens pleasure for the man's sex partner? The "coronal ridge (?)" really only exists on top of the penis, which easily corresponds to hitting a woman's g spot during sex. I'm not saying that Semen Displacement is necessarily wrong, but I think there could be a multitude of reasons that anatomy developed this way. Immediately discounting or downplaying women's sexual selection, and men's evolution in essentially wanting to please their partners, as being a major factor in evolution seems crazy to me!
Makes me think -woman have a variety of shapes inside and outside. To me this lends to compatibility -more or less of it. And some woman are just REALLY COMFORTABLE. do we men as the odd character in the genome have natural , innate dating and mating preferences -or is it just who the girl was on the playground. do we all come from separate Tribes/Varieties that evolved in mutual compatibility -and what do we have when a woman has two widely differing X-chromosomes. And what kind of Man are we when a) we have are Hypothetical Natural Mate X or b) we have a far divergent X.
Reply | Report Abuse | Link to thiswhat' Up With THIS?
Thank you for the your explanation of the long and the short of penis design. At the end of your piece (pun intended) you describe the possibility of a woman being impregnated by semen transported under the foreskin. Has this ever been proven to happen? Do the sperm stay viable and in sufficient numbers under the foreskin "long" enough to fertilize the ovum? And lastly, the "immaculate conception" refers to Mary, Jesus's mother, being conceived in her mother's womb without original sign; what you were thinking of is the "virgin birth."
Reply | Report Abuse | Link to thisThank you for the your explanation of the long and the short of penis design. At the end of your piece (pun intended) you describe the possibility of a woman being impregnated by semen transported under the foreskin. Has this ever been proven to happen? Do the sperm stay viable and in sufficient numbers under the foreskin "long" enough to fertilize the ovum? And lastly, the "immaculate conception" refers to Mary, Jesus's mother, being conceived in her mother's womb without original sin; what you were thinking of is the "virgin birth."
Reply | Report Abuse | Link to thisStupid biased thinking again from an "evolutionary psychologist." This article completely ignores the fact that intact human males have FORESKINS which erotic sex toys do NOT. This is a huge violation of the principle that a lab study should have a high degree of fidelity to the real world. The space between the coronal ridge and the shaft of a human penis is mostly filled up with foreskin when erect and so will tend to interfere with any "scooping" action of the ridge.
Reply | Report Abuse | Link to thisAnother obvious fact ignored by these nincompoops is that if it's genetically advantageous for a human male to root out another male's sperm, why would it not be equally so for other primates?
Unfortunately "evolutionary psychologists" seem to be solely in the business of making up stories that support their own preconceptions. And their preconceptions always seem to circulate around this notion of humans as harem-keepers, as though our nearest genetic kin were actually elk, or elephant seals ... species in which males compete fiercly for females.
This researcher hasn't even bothered to consider what makes humans truly different from apes. It is NOT the genetic need to ensure paternity, as all males of social species (apes and humans) have the same mixture of self-interest and group-interest in their reproductive behavior. In a highly social species, ensuring that your BROTHER has access to a female is almost important as making sure that YOU do. There is some advantage to surpassing your brother, but other considerations (social cohesion, shared foodgathering, etc.) are far more significant to survival of the children one has produced in the sexual union (and thus, one's genetic material).
The HUGE differences between human and ape sexuality involve females, not males. They are: a) the fact that human females are potentially receptive all the time; b) the fact that humans have sex face to face; c) the fact that human females are well equipped to have an orgasm with every coupling. Put all this together and you might find that the shape of the human penis has more to do with satisfying the human female's rather prodigious sex drive, than guaranteeing any one male's ascendancy. There's nothing like group sex to create lasting bonds in a small group of hunter-gatherers, and its to everyone's advantage if the females engage enthusiastically in the activity.
This alternate theory may not be the right one, but it's easily on a par with the 'roto-rooter' theory of penis shape. And it only took a few minutes to come up with.
(APPLAUSE)
Reply | Report Abuse | Link to thisPenis has shape of peeler, the purpose of which is to remove as many seminal fluid from vagina to replace it by a new one - a pretty handy feature in promiscuitive communities.
Reply | Report Abuse | Link to thisThe shape is obvious in circumcised males, does the theory still hold true for the un-circumcised? I'm assuming that the equipment used was imitating a circumcised penis. Which doesn't make for a very convincing case when trying to determine the "natural" development of the penis.
Reply | Report Abuse | Link to thisEvolutionary psychology assumes evolution is goal oriented when more likely it is problem alleviating where purpose is concerned. It's a hell of a stretch to conclude that one or more men's penises would experience the equivalent of knowing the effect to the vgina that oterwise had no discernable effect to the perfomance of the penis. Further, why not assume a counter evolutionary goal for the vagina that allowed it to keep all the semen that it may have eagerly acquired? Or why didn't we evolve a circumcised penis for this process? Evolutionary psychology seems stuck in the silly stage of the theoretical process by this and numerous other examples.
Reply | Report Abuse | Link to thisI subscribe to Scientific American because I love science and the fascinating articles I always find in this magazine. What's up with this story? Am I just not getting it because nothing penetrated. You mentioned shapes but maybe I missed the point. I thought I might learn about the difference between gaining access using the cervix entrance as opposed to the rear exit. Does absence really make the heart on grow fonder?
Reply | Report Abuse | Link to thisThis article doesn't even rate a thumbs down. I'll just give it the finger.
In some other primates the appearance of the genitalia is used to attract mates and signal fitness. Could it be as simple as "size matters" in humans?
Reply | Report Abuse | Link to thisThis theory coincides with the theory of kamikazi sperm, or the morphological features that some sperm have that enable them to attacks other males' sperm while inside the vagina. In other words not all sperm are designed to penetrate the ovum some are designed to prevent genetically different sperm from penetrating the ovum. Just throwing that out there.
Reply | Report Abuse | Link to thisThis theory coincides with the theory of kamikazi sperm, the idea that some sperm are designed to attack other males' sperm to prevent genetically dissimilar sperm from penetrating the ovum. Just throwing that out there.
Reply | Report Abuse | Link to thisAs a lesbian in the social psych field, who doesn't often see any penises, this article was both quite interesting and highly informative.
Reply | Report Abuse | Link to thisPenises! They're so cute, you just want to pinch their cheeks and give them cookies.
As a lesbian in the social psych field, who doesn't often see any penises, this article was both quite interesting and highly informative.
Reply | Report Abuse | Link to thisPenises! They're so cute, you just want to pinch their cheeks and give them cookies.
Try this for size: The wide-radius corona of glans is ideally shaped, according to a simple law of Physics (LaPlace) , to expand in response to slight pressure waves created by contraction of bulb muscles (bulbospongiosus and ischiocavernosus) around the root of the penis. 'Bulbar' pressure waves are carried to the glans by corpus spongiosum. Rapid expansion of the corona of glans triggers a reflex for further bulb muscle contraction, and so on. What initiates bulb muscle contraction during sex? Almost certainly, stretching of the specialized ridged band of the prepuce (foreskin) . Ever wonder what corpus spongiosum does for a living? It is an hydraulic conduit. essential for repeat sexual reflexes. Glans is not a rake; it is a fimely-tuned repeater station essential for the build-up of nervous impulses required to trigger ejaculation. See http://research.cirp.org
Reply | Report Abuse | Link to this5 inches is way larger than average. Try more like a 4 inch circumference - or about 1.25-1.33 inches in diameter, more like the rubber penis purchased for the experiments
Reply | Report Abuse | Link to thisSpeaking of tools, consider the vibrator. Men's carelessness about female satisfaction is behind the now old fashioned female complaint," hysteria," which was the most frequent reason for women to visit their physicians in the late 1800s. That was documented in the curious PhD dissertation that became a book, "The Technology of Orgasm: 'Hysteria,' the Vibrator, and Women's Sexual Satisfaction," by Rachel Maines. She traces the invention and the industrial development of the vibrator.
Reply | Report Abuse | Link to thisIt was originally a piece of medical equipment until one was featured in a "dirty" movie in the 1920s and the doctors abruptly stopped treating "hysteria." During it's heyday as a piece of medical equipment there were ten manufacturers of these devices in the US. Maines' book was published by the Johns Hopkins University Press, apparently unafraid of their history.
It seems that many men aren't that concerned or are even aware that women have orgasms. Still the ones who are aware and think it is their mission to "make her come" gave rise to the faking of an orgasm--to get them to stop.
Someone placed a camera eye to see what happens during female orgasm and captured a series of throbs squeezing shut of the vagina as though pumping the sperm up towards upward towards the fallopian tubes.
How teleological are those scientists...
Reply | Report Abuse | Link to thisHow teleological are those scientists...!
Reply | Report Abuse | Link to thisAn interesting topic. It certainly seems likely that the size of the human penis is part of the display for a mate, and likely the product of artificial selection. Because human women are always sexually available, convincing a partner that sex with him would be fun would factor into a man's ability to reproduce. There are no human societies based on only one male having sexual access to all the females (think a herd of horses), so some mate selection had to come into play.
Reply | Report Abuse | Link to thisFIVE INCHES in circumference! Ouch! We hope this is a misprint!
Reply | Report Abuse | Link to thisThis theory is completely flawed - the coronal ridge is not functional in uncircumsised males, which prevailed in early evolutionary man, meaning Jews and Muslims are the promiscuous ones that needed that corona exposed
Reply | Report Abuse | Link to thisFive inches IS the circumference - it's not a misprint (at least for me...)
Reply | Report Abuse | Link to thisA circumference of 5" implies a 1.59" diameter, not usually an "ouch" matter--quite average actually. Perhaps, it would be more of an "uumm"??? Maybe often leaving a woman feel like a new man?
Reply | Report Abuse | Link to thisThe coronal ridge is functional in uncircumcised males. The foreskin might cover the glans when the penis is flacid, but when its fully erect and thrusting, I assure you that the entire glans are uncovered; in fact, the fold of skin which is the foreskin becomes stretched out and the entire shaft is smooth. If anything, the foreskin probably increases suction, acting somewhat like the ring around a piston. So, score one for the theory, another for those who abhor genital multilation, female and male; and yet another for the greater sensitivity and pleasure of the unmultilated and their partners. More intact nerve endings to transmit pleasurable sensations, greater range of penile motion (with less need for
Reply | Report Abuse | Link to thislubes) and with more thrust--and now we learn with greater possibilities of scoring cervical hits and fallopian home runs!
The last example of transferring Mike's semen to Amy via the foreskin is as good a reason as any for male circumcision...
Reply | Report Abuse | Link to thisSince Ev-Psych (the "cold fusion" of the behavioral sciences) seems fond of confirmation bias let's add that the "sperm extractor" hypothesis must "explain" that men have evolved to be inconsiderate lovers because vaginal tenting during orgasm would disrupt pumping. :-)
Reply | Report Abuse | Link to this---
Seriously, as a non-casual sex blogger I'm familiar with how sex toys for men are manufactured. Generally no matter how "anatomical" the exterior might appear, the interior is designed to facilitate quick removal of fragile, pthalate-softened plastics from the molds. So while its possible that dime-store dildos resemble male anatomy there's just no way that sex-toy vaginas resemble human vaginas. Also, unlike penetratable sex toys, actual human women's vaginas are highly sophisticated and dynamic.
As are, one feels obliged to remind Ev Psychs, actual female human beings.
Call me a crazy naive un-scientific rebel but does the, you know, *psychological* part of Ev Psych ever consider that women's visual or sensory preferences might have *something* to do with men's shape? I believe Scientific American has previously published articles on female choice in (rapidly evolving) African cichlid fish, including one where tail fin length preference is so strong that females will swarm a male with experimentally-enlarged prosthetic tail fins, and even prefer males of related species when those have been outfitted with said prosthetics. So female choice demonstrably matters among animals. Why not humans? Because Ev Psych is so dead set on justifying Ozzie and Harriet as the human species type you only drag in behaviors of really, really distant organisms in cases that justify the status quo. (David Barash memorably proposed microscopic parasitic acanthocephalan worm behavior as some kind of "adaptive" justification for rape.)
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That's obviously not to say human penises, like all penises, aren't shaped by evolution. Nor is it even to say that the shape of penises aren't effective at sperm or other fluid removal. The refractory period would a good hypothesis whether the shape was adaptive or just coincidental... although you'd think it would tend to benefit subsequent partners who could displace first-partner sperm without worrying about being displaced in turn. So which is it, to prevent inadvertent pumping of one's own semen, or to pump out a prior partners? It stands to reason it can't be both.
But whatever. Given that our close relatives are even more promiscuous compared to humans it's hard to imagine there's been enough selective pressure at the margin to evolve large coronas only to displace competitor's semen in just 2-300,000 generations since we diverged from common ancestors.
Evolutionary Psychology: so cute you just want to pinch its cheeks and pat its head. And tell it to grow up.
figleaf
Donkeys and horses have a penis that is just like a human being, with the same kind of head and everything. I'm sure if you circumcised them it would look the same, but I'm not really sure. Even if there were moyles for horses, I don't think I'd access their services, though I think it would create a charming presentation if such a thing were done with dogs.
Reply | Report Abuse | Link to thisCould this be evolutionary evidence as well to the effect that women are indeed, trollups?
Reply | Report Abuse | Link to thisJust a joke ladies... I love you all! :-)
You sure are a weird one I can't see this having that much merit.
Reply | Report Abuse | Link to thisI agree with "Critical Thinker". I must also say that males who are circumcised don't know what pleasure they are missing while having sex. Circumcising of babies should be banned. It is a form of torture to the babies, whose only response is nothing but crying in pain helplessly as they are forced to undergo this medievial procedure.
Reply | Report Abuse | Link to thisThe monogamous relationship is, however, the norm and therefore the male will more often be competing against- and removing- his own sperm rather than another male. This would seem to outweigh the competitive advantage in the majority of cases.
Reply | Report Abuse | Link to thisBut on reflection, perhaps this is the advantage.
Sperm motility falls off very quickly- in half an hour of so - and the least motile sperm- which are unlikely to do the job even if still alive-may prevent the new more motile sperm from reaching and fertilizing the egg. Hence removing them to clear the path, may be the advantage. In the lab, sperm motility has been shown to be very easy to reduce and oils, lubricants and saliva can all reduce motility enough to stop fertilization (don't rely on it though). Semen would also, surely be enough?
Newly mating couples tend to have sex several times in quick succession but the male who has not had sex for a while probably has a build up of dead or mis-shapen sperm, so the first time isn't necessarily the most fertile time for partners that meet then part, and that may also be something to think about.
It is quite obvious that neither the author of this story nor the folks that did the research are uncircumcised! And, for those that think the uncircumcised penis performs the same sucking action as the circumcised penis, well, you are just simply dead wrong! You obviously have not seen enough uncircumcised penises to know any better. Not all foreskins retract on erections, nor do they all retract enough to expose the coronal ridge during intercourse. I might suggest that another study be done with uncircumcised penises only - I mean, COME ON, humans didn't evolve circumcised penises!! And a thorough survey of uncircumcised penis functions and types would be the first order of business. As reported in this article, the info presented is absolutely worthless due to the major flaws that would be glaringly obvious to anyone who actually has an uncircumcised penis and especially to one whose foreskin does not work exactly the same way the author and researchers seem to assume it does.
Reply | Report Abuse | Link to thisThis is an excellent article and I look forward to future articles with anticipation.
Reply | Report Abuse | Link to thisI find the discussion missed a key point.
Reply | Report Abuse | Link to thisThe article starts with how weird the human penis is, and how it's most unique among animals. But in the remainder of the article, there's no mention of why humans evolved a phallus in this way but males of other species did not. Presumably the selective pressures such as the removal of other male's sperm and the getting your sperm as close to the goal as possible are entirely valid from an evolutionary perspective among humans as much as any other animal. If the fundamental argument in support of the evolutionary success of the weird human penis is the weird human female genitalia, then aren't we better served looking at CO-evolutionary mechanisms rather than how the human male genitalia evolved to accommodate and best utilize the female bits?
Does the penis really fill/expand to fit the vagina, or does the vagina adjust it's size to accommodate the penis? I thought it was the latter, not the former.
Reply | Report Abuse | Link to thisAlso, as far as the displacement goes, wouldn't the initial thrust push the other male's semen into the cervix? Because the suction effect would only happen as the penis was pulled out: when the penis first enters (and after any subsequent removal of the penis out the vagina entirely) shouldn't it be preceded by a plug of air?
Reply | Report Abuse | Link to thisNot to be indelicate, but deep thrusting can incorporate air into the vagina, and that could bring the other male's semen closer to the target.
Did the researchers just use a blind-end vagina, or did they simulate the cervix/womb attached to the end of the vaginal vault? It would be interesting to reproduce the experiment, load two kinds of fake semen with fluorescent tags, and see what ends up past the cervical os.
Finally, if the unique shape of the penis is to prevent rival males from impregnating a specific female, are there any similarities in the more promiscuous primates, like bonobos or chimps?
It is stunning to me that individuals that are highly intelligent still talk about evolution...no, it's ridiculous. The human penis, as you pointed out in your article, is unique; similarities between animal and human penises, besides function, is non-existent. You contradict yourself several times...as an evolutionist, should you not be working for the survival of the human race? Wouldn't that be an instinct? How does one evolve into being a homosexual? All the sudden one day at the watering hole, Ape 1 looks at Ape 2 and says, "Mmm. Gonna get me some of that male!" I find it remarkable that you are a homosexual evolutionist! It spits in the face of evolution...you are the best argument I have against evolution.
Reply | Report Abuse | Link to thisPlease find and read the book Sperm Wars - a lot of the ideas covered in this article are thoroughly explained (and with anecdotal evidence thrown in, too). I stumbled upon this book at a used bookstore, and it's title stopped me and made me laugh, but the book is very serious. This book even looks at rape, and the biological ramifications (rape can stimulate eggs to be release off-cycle!) thereof. This was a fascinating article - I hope more folks will think about their genitalia with a scientific mind. In April, at workshops for my career, (I'm in the adult "toy" industry) sex educators Sheri Winston and Tristan Taormino talked about the anatomy of the vagina and anal sex in great detail. Perhaps this gentleman needs to be invited to speak to my company to educate us on the penis, as well!
Reply | Report Abuse | Link to thisI guess this explains a question I've had for years, of why all the in and out, with extended vulnerability to attack from others, rather than just in and squirt. But it leaves another question. Why wasn't this shape invented eons ago, before humans, considering that there have been some other species that aren't always very monogamous? I've also wondered, considering that some other species seem to have an actual bone or gristle in their penises, when did this change in human evolution, and why?
Reply | Report Abuse | Link to thisI guess this explains a question I've had for years, of why all the in and out, with extended vulnerability to attack from others, rather than just in and squirt. But it leaves another question. Why wasn't this shape invented eons ago, before humans, considering that there have been some other species that aren't always very monogamous? I've also wondered, considering that some other species seem to have an actual bone or gristle in their penises, when did this change in human evolution, and why?
Reply | Report Abuse | Link to thisVery interesting! As A side note my girlfriend use to say how she loved that I was not circumcised as she found my penis more pleasurable than other circumcised men she had been with.
Reply | Report Abuse | Link to thisI giggled through the whole article couldn't help myself..i dont think it encourages cheating and it might give me a little insight to the ego that goes along with the phalis. The imagination of a woman is a powerful thing.
Reply | Report Abuse | Link to thisSo I feel like this mostly refers to the shape of a circumcised penis, which would be most common for adults today because it was not until recently that some people realized there was no medical reason for it.
Reply | Report Abuse | Link to thisNow, what about an UNcircumcised penis? As that is the way the human male is born, does this theory apply the same way? I am just curious if that makes a difference here or not.
The story is fascinating. The bit about Josh, Kate and Amy.. yuk. One would hope Amy wouldn't get so close to the guy who has not even showered since his last "encounter".
Reply | Report Abuse | Link to thisJust like a uptight better than thou and frustrated homosexual to make a stupid comment like "Lonely Straight Guy" for the use of a artificial vagina. I wonder how many artificial hairy latex deriair's this articles frustrated author has had to use?
Reply | Report Abuse | Link to thisSo if a larger penis has the advantage of depositing sperm deeper where less endowed competitors could not scrape it out of the vagina wouldn't it necessarily follow that those with smaller penises came from less promiscuous ancestors where this advantage was not necessary to ensure survival? Smaller penises therefore represent a more civilized and therefore more highly evolved lineage. Suddenly I'm quite proud of my average existence.
Reply | Report Abuse | Link to thisab at 02:51 AM on 05/06/09
Reply | Report Abuse | Link to thisDoes the penis really fill/expand to fit the vagina, or does the vagina adjust it's size to accommodate the penis? I thought it was the latter, not the former.
Yes, it is indeed the latter. Any heterosexual man would know this. That is the problem when a queer researcher starts discussing issues they obviously know nothing about.
The other glaring mistakes in this article just made me laugh. I'm surprised the researcher even has a job in the field.
In closing, I would like to point out to the researcher an others, that evolutionary changes commonly happen for a multitude of reasons, not just one. Instead of semen extraction though, I would favour the "plug" idea and an idea that hasn't been mentioned yet, that any women will tell you.
That reason is pleasure. The shape of the penis especially at the head helps in stimulation of the g-spot. Since humans have sex for pleasure as well, unlike many other animals, it is a good hypothesis as to why our penises differ.
Perhaps I am missing something, but why didn't apes also develop this trait if it is so evolutionarily advantageous? Presumably they also have different partners within short time-spans.
Reply | Report Abuse | Link to thisthe hypothesis is based on the assumption that it is evolutionary desirable for the second male to remove the sperm from the first recently entered male. But why would evolution not favor the first male's sperm? The first male may have been stronger or more aggressive or was healthier than the subsequent male.
Reply | Report Abuse | Link to thisIn addition, I suspect that your mechanical simulation using plastic penises is flawed. I wonder how the corona is able to pull back more sperm than it pushes forward.
I guess the argument that homosexuality is nature is blown to smithereens, since the penis is designed to fit a vagina. The Designer is magnificent isn't he?
Reply | Report Abuse | Link to this"...between five and six inches in length and averaging about five inches in circumference."
Reply | Report Abuse | Link to thisI think you mean 5 centimeters.
After reading the first paragraph, I went to the kitchen and ate a banana. I just realized how weird that was.
Reply | Report Abuse | Link to thisGiven that penile evolution occurred without circumcision, I find the experimental design somewhat sterile (no pun intended). I suspect in most cases that the foreskin in uncircumcised penises retracts fully during erection, adding to the size of the coronal ridge, This in turn can only contribute to enhancing the vaginal seal properties of the coronal ridge, since this basically is the only time the foreskin would naturally be in this position. I suspect this contributes to the possibility of more motile sperm going through the cervix, as opposed to removing another males' sperm.
Reply | Report Abuse | Link to this"[...] men are designed [....]"
Reply | Report Abuse | Link to thisWasn't this an evolution oriented article?
Response to: albertsonrich
Reply | Report Abuse | Link to thisReproductive success is not limited to the actual sexual intercourse alone. As Homo Sapiens we have the longest adolecense among all species. For reproduction, there are basically two main reproductive strategies : "r") Maximizing the numbers of offspring, and "K") - Maximizing the quality of resources and parenting put into each child. Strategies may also combine these two versions in a trade-off.
Especially in colder climates, where the winters were harsh and long, children tend to mature at a later age than in the hotter climate zones. Since the human brain is not fully developed until about age 25, a slower pace of sexual maturation would be selected for if the environment poses severe circumstances that place extra demands on the quality of parenting.
In a warm climate zone where the seasons do not place extra demands on a strong family nucleus for the upbringing, and where the sexual maturation level is fast, sex with many different partners has traditionally resulted in a "r"-strategy reproductive bonus, while in colder climate zones a single stable spouse has in the past rewarded a reproductive "K"-strategy.
Going a step further in the "r" / "K" strategy division, and incorporating the theory of this above article, I would make a few assumptions:
Reply | Report Abuse | Link to this("r" - Maximizing the numbers of offspring, and "K" - Maximizing the quality of resources and parenting put into each child)
I would expect humans who have evolved in warm climates where a stable family nucleus has not been fundamentally necessary for the survival of the offspring, to have not only engaged more in "r"-strategy behavior, but also grown longer and bigger penises to replace the semen of competitors.
Objections to this hypothesis could point out the present day warm climates of Asia, and the fact that the penises of asian men are generally shorter than in both Africa and Europe. However, the mongoloid eye-fold suggests that the Asians have evolved in a cold climate, and therefore it would be logical that they have generally engaged in more "K"-strategy sexual strategies.
Penis-size may therefore be an indicator of the evolutionary history of either a dominant "r" or dominant "K" reproductive strategy.
When it comes to the question "why is the male penis 5-6 inches long" - we should remember the lesson of the man hole cover.
Reply | Report Abuse | Link to thisIf you're ever asked "why are manhole covers round" - the proper answer is "because manholes are round". Likewise, when asked "why are penises 5-6 inches long" - the answer is "because that is the depth of a vagina".
I appreciate Jesse Bering's efforts of making light of his orientation, however I still do not think he goes far enough in raising the issue of the size of a vagina when looking into the difference in penis size between humans and apes.
After all - humans having larger penises cannot because of human promiscuity - because most apes are more promiscuous than humans. It is not competition between human males that causes human penises to be larger when there is even more competition between chimpanzee males.
This is what gives evolutionary psychology such a bad reputation for projecting locker room bravado onto our ancestors - the way evolutionary psychologists promote the sexiest possible answer to a question - penis size is caused by promiscuity - when it simply does not fit the evidence.
The question you should be asking is why human women have different vaginas than primates. But the answer to this is not to do with promiscuity, so it doesn't make a good a story, so evolutionary psychologists don't bother.
I am not convinced of the 'selfishness' of evolution; wherein the male of a species one-ups the other males for the increased chance of propagating one individual set of genes. If nature truly worked this way would any of us be here? Wouldn't it be more logical to say that a Vagina would ideally be designed to handle and incubate the sperm from multiple partners than it would be to say that the glans is an evolutionary adaptation to cause the competition to be 'ejected' from said Vagina? Why does evolution, which is supposed to work for the benefit of the whole species, seem so narrow minded and greedy? I think we are guilty of anthropomorphism with our ideas and observations. Of course, Just because you can see something, doesn't make it so. I think people get lost in their intellect.
Reply | Report Abuse | Link to thisPerhaps it is the way it is simply because it f i t s. The conclusion can be tested simply by understanding that if it did not fit, no one would be here; the moment penises and vaginas had become a prerequisite for species propagation it would have been a big fat 'game over'.
It's so funny.But I don't believe it at all.
Reply | Report Abuse | Link to thisHere I thought it was all about aesthetics. Does this mean the the guy who was last is the fittest?
Reply | Report Abuse | Link to thisI remember seeing a documentary on this on the Learning Channel (?) in 1999. The show talked about the shape of the Glans and also about the 'soft plug' effect. The seminal fluid congeals after being deposited, supposedly plugging up the cervical area, and making it less likely for the stuff to slide out postcoitally. The documentary had footage of pointy mouse weenies too, as certain mice develop a 'hard plug' like hardened elmer's glue at the vaginal entrance, which the next suitor has to punch through. Ouch.
Reply | Report Abuse | Link to thisWhile my anthro background is very limited, I think also there is a fair amount of orgiastic social interaction in humans' more "primitive" past. One example I read about is sexual hospitality, practiced by some Native American tribes according to early explorers' accounts. Another is the practice of sleeping together in tribal or extended-family groups (for warmth in crude dwellings) in prehistoric England. It seems there was a lot of group sex going on there too. I wonder if this was prevalent through most of prehistory? Any prehistoric anthropologists want to weigh in?
The theory sounds good but why wouldn't other primates also have developed the same ridge for all the same reasons?
Reply | Report Abuse | Link to thisI think Desmond Morris said years ago in the Naked Ape that humans were the only primates that didn't have a bone in their penis. No mention of that in this article, makes the article lack backbone. And montavilla, that is where you went wrong, they don't want cookies, they prefer a nice bit of crumpet.
Reply | Report Abuse | Link to thislet me explain why the penis is shaped the way it is. long ago, three countries did many tests. the Russians after spending millions on research found that the reason why the penis is shaped like that is because it is the right shape so that is forms a good seal with the inner vagina to aid in fertilization of the ovary. The Americans after millions of dollars of research found that the reason why it has that shape is so it doesn't slip out of the vagina during intercourse. The Polish spend about 25 bucks on the research (the cost of catering) and after about 30 min of research they found that it's shape prevents you from hitting your self in the eye while masturbating.
Reply | Report Abuse | Link to this"...the human penis is actually an impressive “tool” in the truest sense of the word, one manufactured by nature over hundreds of thousands of years of human evolution."
Reply | Report Abuse | Link to thisAnd continually tampered with by Americans (and to a lesser extent other English-speaking countries besides the UK at present), and those of certain religious persuasions - who think they've found a better model.
"That is to say, if you start with what you see today—in this case, the oddly shaped penis, with its bulbous glans (the “head” in common parlance), its long, rigid shaft, and the coronal ridge..."
...and the bilayered tube of tissue that surrounds the glans while flaccid, secretes and contains natural lubricants, and rolls continuously out across the shaft and back over the glans during sexual activity...
Oh, and the frenulum doesn't attach the "shaft" to the glans - it attaches the FORESKIN to the glans. Frenula serve the purpose of attaching moveable structures to more static structures. The shaft isn't mobile and free enough to require this type of tethering.
The frenulum is also sometimes removed, partially, or pretty much completely, during circumcision - so some men do not possess one.
The remnant of frenulum that most cut men have is part of the remnant of a whole little flap of inner foreskin all around the penis that was left after the initial cut - that has basically "fallen back" onto the shaft and healed against the cut line. This is why the scar is often about an inch or so behind the head, even though the initial cut would likely have been made around point of the corona. This is also why the area between the glans and the cut-line is often pinker in white men than the shaft-skin beneath the cut-line - because it is not actually normal skin: it's pink mucous membrane.
There, I've said my piece. I'm not crusading - simply correcting a few errors and omissions that the author could probably hardly help but make - as well as providing a little more anatomical information to boot.
Perhaps you might have named your article "The Shape of Things to Come"?
Reply | Report Abuse | Link to this
Reply | Report Abuse | Link to thisSeems like the shape of the vagina would evolve primarily for spawning, so the penis would have to either accommodate the vagina's specifications, or not complete it's task. Thorry dude, your massive and oh so important tool has to play second fiddle. Try another wacky theory, huh? These are fun.
Do you folks ever discuss how your own blindspots effect your interpretation of past events? Because this seems to be a bunch of dudes with insecurity issues more than anything else. What conclusive evidence do we have that this is not the case? And why exactly is it important that we know why any body part developed the way it did, anyway? Seems like a waste of funding when we have people dying of cancer.
Ah, interesting point, FrederalXpress. If evolution were truly efficient, and if evolution truly intended big brawny ape-men to gang rape the dainty little girl-apes, then the vagina would have evolved with the ability to save multiple sperm from different donors, and keep the best.
Reply | Report Abuse | Link to thisSo logically, either evolution is not efficient, or evolution didn't intend for gang rape. (I know some of you scientisty types just luuuuuuuuuuve that gang rape theory.)
Gosh, isn't this fun.
it is wide world read your magazine, is it too much to ask the author who pretends to be a scientist, to use the metric system or at least use equivalences.Join the learned world, SA
Reply | Report Abuse | Link to thisSome of this conjecturing seems almos naive to the rational mind. It would seem at times that the theorists have no feel for number and how it plays out in the evolutionary scenario. To imagine that an episodic incident such as invasion of one tribe by another could have an influence on the evolution of the biology of homo sapiens is to have no feel for the science of large numbers. Firstly, a village that is invaded and pillaged even on a monthly basis is unlikely to have survived as a village for very long at all. Secondly, even in such a scenario, the incidence of normal coitus compared to the incidence of rape over CENTURIES would be minuscule. How could something that happened one thirtieth or less of the times interfere with the influence of something that happened 29 times out of 30?
Reply | Report Abuse | Link to thisIt is much more reasonable to suppose that especially in warm climates where loincloths did not conceal much, that just as strong bodies, regular features, high vitality appear attractive to females today, so too did large phaluses also affect the number of matings available to an active male. Clandestine encounters would have been easy and not as subject to moral qualms. Indeed there may even be a correspondence between phallic size and testosterone levels, which suggests that the more obviously male a person might be, then the more partners he was likely to have. Phallic size would have been seen as a component of maleness, and even though this is largely concealed these days, the other male attributes certainly affects a male's attractiveness to likely partners, even today.
Bravo! At last there is Eve's solution in this matter - which DOES matter! Charle Darwin already mentioned the role of ladies' choice!
Reply | Report Abuse | Link to thisThey come in all shapes and sizes; no "deja vu" there! evviva l' evoluzion!
Reply | Report Abuse | Link to thisSeveral of us want to establish an educational museum or display of Human penises and Human male reproductive systems. We want to display as many interesting facts as possible, along with actual plastinated Human penises, testicles and scrotums. We feel this can be done in a professional and educational way - even more so than the Iceland Penis Museum has done with animal penises (until the American penis, Elmo).
Reply | Report Abuse | Link to thisWe would like your support.
adroitbiological@hotmail.com
I have been looking into this a lot as I am not happy want to try <a href="http://www.sizegenetics.com">penis enlargement</a>but I wonder how this affects my future and wonder if I will develop abnormalities
Reply | Report Abuse | Link to thisThe author and all who responded seem to think reproduction as the only function of sex. Reproduction have been assigned to sex, as that is one activity of all living beings rarely done in excess thereby population do not explode threatening the very existence of the being. The shape of penis is linked to the 'pleasure' function of sex and the enhancements offered by different shapes is worth studying.
Reply | Report Abuse | Link to thisThe human body has evolved to be as any other mammals , to preserve the specie of us humans . The biology of the human female has been physiologically shaped to reproduce by impulse of chemical reactions, involuntary manner , driven by hormones , and chemistry reactions to an array of sensations , and feelings ,...
Reply | Report Abuse | Link to thisthose feelings are responses to incretion of those hormones that react to the environment , oround us .
With the only end , of preservation of the human race , with out knowledge of what we are unconsciously doing , ...
we attribute all that to, attraction, love , as a way of explaining our basic survival of the specie .
As we know the female is as a result biologically shaped to receive multiple partners , with secretion of acidity with in the womb to kill sperm of other males , once the egg is fertilized .
All behind that , cellulous , love, position, unger , are reactions, involuntary thoughts , nothing more , created by the same hormones in our brains .
To top all that . we are imperfect machines , that go wrong once in a while , and to make things more difficult , we try to regulate through laws of society , to be able to call us human , organized , civilized , orderly , not allowing our bodies impulses to take over to have sex openly as nature intended .
AL Bottini
The human body has evolved to be as any other mammals , to preserve the specie of us humans . The biology of the human female has been physiologically shaped to reproduce by impulse of chemical reactions, involuntary manner , driven by hormones , and chemistry reactions to an array of sensations , and feelings ,...
Reply | Report Abuse | Link to thisthose feelings are responses to incretion of those hormones that react to the environment , oround us .
With the only end , of preservation of the human race , with out knowledge of what we are unconsciously doing , ...
we attribute all that to, attraction, love , as a way of explaining our basic survival of the specie .
As we know the female is as a result biologically shaped to receive multiple partners , with secretion of acidity with in the womb to kill sperm of other males , once the egg is fertilized .
All behind that , cellulous , love, position, unger , are reactions, involuntary thoughts , nothing more , created by the same hormones in our brains .
To top all that . we are imperfect machines , that go wrong once in a while , and to make things more difficult , we try to regulate through laws of society , to be able to call us human , organized , civilized , orderly , not allowing our bodies impulses to take over to have sex openly as nature intended .
AL BOTTINI
All this seems plausible (Gallup's research), but he still has to explain why, a) male chimpanzee penises are not bigger, wider and ridged, as chimp females are notoriously promiscuous during an estrous cycle and mate with many males, and b) why humans have so many other traits that suggest an increasing commitment to monogamy-like mating patterns over the course of our evolution (moderate sexual dimorphism; increased paternal investment; etc) yet still this one very potent "weapon" of rampant polygyny. I'm also a primatologist who has studied chimps, and maybe this says something about how I view my own penis, but male chimp penises always seemed very long to me, but very thin. I really think there's more to the story here than what Gallup and Bering suggest.
Reply | Report Abuse | Link to thisThat's why we use condoms people; so a "hypothetical" scenario like the one mentioned doesn't happen to anyone. Very great read, I am impressed with the evolutionary aspect of the penis and almost have a newfound respect for it. But what about the thickness of a shaft? Does that have any evolutionary benefit?
Reply | Report Abuse | Link to thisI just read this article through a link with the Wall Street Journal. It reminded me of a joke we used to tell many years ago in Special Forces about our brethern in the Airborne and Ranger units. I think you'll appreciate its relevence to evolutionary psychology. It also adapts nicely to less, shall we say, well respected professions.
Reply | Report Abuse | Link to thisThe military, in its infinite wisdom, wanted to know why the head of the penis was larger than the shaft. It gave 10 million dollars to the 82d Airborne Division and told them to report back in 5 years with the answer. 8 years later and 5 million dollars over budget, the 82d finally reported back. The head was larger than the shaft in order to give the women more pleasure during intercourse.
Thinking there may be another explanation, a Ranger Battalion were given 5 million dollars and three years to investigate. The Rangers were six months late and one million dollars over budget, but reported that the reason for the discrepancy was to give the man more pleasure during intercourse.
Faced with two different answers, the military turned to the Green Berets. They gave a 12 man Special Forces A-Team one million dollars and a year's time to solve the conundrum. Special Forces reported back at dawn the next day. They also returned the entire one million dollars less the cost of a keg of beer. The reason the head of the penis was larger than the shaft was to keep your hand from slipping off.
Case closed!
Yes , theories so fine and proved beyond doubt.# but an other aspect i found:= Re the shape of the phallus:if you looked into and at the shape of the opened external genitals of the femme, it is shallow boat shaped, wide/narrow/juicy slippery/smooth/ and attractive pink. A man;s erect rod shape usually takes a bit of time grinding to find the entrance, and the glory round tip of the pestle glides so well attempting entry into the hole in the eager mortar. and this also helps the fem to lube and tumesce herself with the gels in and around.# in the knee-elbow position the entry is straight thru the diamond between the bums and the thighs, into the hole of the vagina, and the sperm shoots direct into and thru the mucous plug of the cervix.# semen displacement comes in for just the 1% cases of polyandry.=
Reply | Report Abuse | Link to thisuh. Like wow.
Reply | Report Abuse | Link to thisAnother interesting argument for polywoggery.
Yep, it is only size that matters. And it is just for introductions to many years invested in child rearing.
Reply | Report Abuse | Link to thisBering ignores the prevailing worldwide cultural and emotional norm throughout history that monogamous women are the most successful in procreation. That is because the survival of her children is in large part dependent on the father's commitment to raising them. And the father's commitment is largely based on the certain knowledge from his mate's behavior that her children are his children.
Bering's discovery is pure coincidence.
"For the evolutionary psychologist, the pressing questions are, essentially, why is it like that? and what is that for? The answer isnt always that its a biological adaptationthat it solved some evolutionary problem and therefore gave our ancestors a competitive edge in terms of their reproductive success."
Reply | Report Abuse | Link to thisSounds like a just so story to me without some empirical data.
"For the evolutionary psychologist, the pressing questions are, essentially, why is it like that? and what is that for? The answer isnt always that its a biological adaptationthat it solved some evolutionary problem and therefore gave our ancestors a competitive edge in terms of their reproductive success."
Reply | Report Abuse | Link to thisSounds like a just so story to me without some empirical data.
This is very poor science. The author posits a 'theory' of 'semen displacement', then attempts to prove it with circumstantial evidence. It's nonsense.
Reply | Report Abuse | Link to thisPeurile prose doesn't help if this writer wishes to be taken seriously. I mean 'don't go West young man, go deep' - what the hell is that if not adolescent humour? Jesse - grow up, go back to school, then try again.
Interesting, but it might all seem silly in 50 years when the scientific community has another few paradigm shifts in their thinking and methods. Just like when they used to tell us that the solution to pollution is dilution.
Reply | Report Abuse | Link to thisnice blog se at http://www.penisenlargement-pills.org
Reply | Report Abuse | Link to thisIts not what the male thinks.The female who isn't treated right ,in the end won't produce offspring.So the point is if you don't stick around it doesn't matter what your penis looks like.The next male who stays around will kill your offspring, so your size and appearance doesn't matter.How well you take care of her does.
Reply | Report Abuse | Link to thisAre you serious? How on earth can anyone conflate manual activity with SEX TOYS as being representative of what goes on in human sex, except in the most broad outline?
Reply | Report Abuse | Link to thisJust goes to show the usual quality of "science" that is prevalent in the evo psych world.
This was the most fascinating article I have ever read! I'm totally gonna look up your book. I would love to sit and decipher how Scientific American can compete with the sales of like-the-omg-number-one-selling-magazine-out-there: Cosmo-like-yeah-ok-lol, all day long. I am in love with all things psychology, as far as it reaches in every field from astrology to penis pumps to criminal justice/cival rights.
Reply | Report Abuse | Link to thisAll-in-all I would first love to congratulate you again (as cliche` and "gay"-now that's a whole new topic, that may sound) on all your accomplishments so far in your career.
For the record, I would like to point out that, I by-no-means meant disrespect in my previous mention of the topic "gay"; I truly hope to attain a response back from you or Scientific American, in fact, on this post to you.
Isn't that a different topic: The Fairy Tale of A Career Come True. I ponder perhaps if you, doctor, actually psycho- dyagnose your fans, foes, and colleagues responses to your elaborate theories peppered with facts that spiral down into a dozen other univers- relevant topics. How would you ever leave your computer screen, if you are part- taking in the very act that is consuming your life, right now?
Any way, I hope that you can plainly see that I'm entirely sincere in this post to you. Oh, and before I end this note, I wanted to mention that your skill in conveying letters of eternal meaning are very powerful, probably more so than your aware of. Also, please consider that of responding to me intentively. Why We Ramble: A Guide to Understanding Communication among the most Intellectually Complicated Creatures in Existence That We Are Aware Of, that would be a funny title of a psychology article, in case you were wondering and only if you caught the joke. I love to be cliche`; I believe so much can be revealed in the written words of other souls. Or am I only studying an elaborate but poorly- understood exspression of an evolutionary extent of chemical make-up? Did I just bring up Religion? The scandal, the controversy, the ignorance, and last but not least- those of us that have been cast in this exile- blindly heaving forward on one good leg and what we have of war...
Thank You for listening and Good Night.
Serina Jean Grimes
Serinajean@gmail.com
Wo wo wo - hold up! Only gang rape? Please. As an unattached female, I can tell you in those three days around ovulation when I am extremely randy, I have on several occasions in my life had sex with two different guys within three days. I am the only gal to do this in the past 3 million years? Given that I'm less likely to use birth control during that time, and less likely to use it with the random partner - I guess the size of those 'coronas' could still be evolving... ;-)
Reply | Report Abuse | Link to thisKosmiko - exactly the opposite! Doesn't reflect on men having multiple partners as much as it reflects on women having multiple partners ;) I've read some interesting data on the likelihood of one lone, unattached male impregnating a lot of female not attached to him (in one famous case a helpful priest!) - Probably not cheating and getting yourself home each night just to be sure is the best option?
Reply | Report Abuse | Link to thisI find it interesting that nothing in the article mentioned a comparison to any other mammals penis. Most mammals dont have bulbous penis. This comparison in the study needs to be of importance.
Reply | Report Abuse | Link to thisSo I am intrigued by the suction theory and the axiom of the phallic design being to ridding the vagina of foreign sperm, but I am wondering why other mammals are without this design since ridding the vagina of foreign sperm is as critical as with humans. Could it be in their case, the more sperm the merrier? Perhaps.
I have for some time thought the coronal ridge is unique with the human male for one purpose&. for the pleasure of the human female. Our maker made us unique in many ways and one very important way is the enjoyment in the sexual union of the man and the woman. I recognize the above studies are quite valid, however did those studies take place before the universal belief in the G spot or did those educators and scientists look only at the reproduction aspect of reproductive intercourse and not the pleasure of intercourse.
I would ask them if they feel the penis would so affect the G spot if the penis didnt have a coronal ridge. Other mammals have sexual intercourse for reproduction only. We have all seen dog penises& reproduction only.
The G spot is located just inside the vagina on the front or topside. Sexual intercourse In the missionary position the coronal ridge rubs exactly against the G spot. And indeed, do other female mammals have a G spot? Of course, I dont know the answer to that question or if anyone does, however my logical mind assumes that none do, or very few.
I would ask them to ask any female who has a sensitive G spot if she felt (no pun intended) having intercourse with male with a penis without a coronal ridge would be as enjoyable.
Come on women, chime in on this. Do you feel a difference in a large coronal ridge vs a small one? I realize that this is only part of the enjoyment of a sexual union therefore can be difficult to measure, however some women should have an opinion. Let's hear your thoughts.
Reply | Report Abuse | Link to thisI find it interesting that nothing in the article mentioned a comparison to any other mammals penis. Most mammals dont have bulbous penis. This comparison in the study needs to be of importance.
Reply | Report Abuse | Link to thisSo I am intrigued by the suction theory and the axiom of the phallic design being to ridding the vagina of foreign sperm, but I am wondering why other mammals are without this design since ridding the vagina of foreign sperm is as critical as with humans. Could it be in their case, the more sperm the merrier? Perhaps.
I have for some time thought the coronal ridge is unique with the human male for one purpose&. for the pleasure of the human female. Our maker made us unique in many ways and one very important way is the enjoyment in the sexual union of the man and the woman. I recognize the above studies are quite valid, however did those studies take place before the universal belief in the G spot or did those educators and scientists look only at the reproduction aspect of reproductive intercourse and not the pleasure of intercourse.
I would ask them if they feel the penis would so affect the G spot if the penis didnt have a coronal ridge. Other mammals have sexual intercourse for reproduction only. We have all seen dog penises& reproduction only.
The G spot is located just inside the vagina on the front or topside. Sexual intercourse In the missionary position the coronal ridge rubs exactly against the G spot. And indeed, do other female mammals have a G spot? Of course, I dont know the answer to that question or if anyone does, however my logical mind assumes that none do, or very few.
I would ask them to ask any female who has a sensitive G spot if she felt (no pun intended) having intercourse with male with a penis without a coronal ridge would be as enjoyable.
Product of evolution? Looks like a classic example of Intelligent Design to me. Where would a localized blind mindless natural selection mechanism, which hasn't the foggiest notion of where anything and everything is evolving to, or even why, ever get the perspective to produce this effective tool for a perfect match. I stand in awe!
Reply | Report Abuse | Link to thisThe penis shape was made to penetrate gracefully the vagina and deposit sperm to its most inward part. Thrust has nothing to do with vacuum of rival sperm why not watch nature nature! The worm stretch and pull itself to move forward.The only thing we have to consider is that the thrust of the penis with repetitive friction movement, arouse the woman and help the muscle of the vagina to expand and open up the access to the upper part of the uterus. I learn it from experience.
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Reply | Report Abuse | Link to thisThe more likely main function of the coronal ridge is to distribute a woman's natural lubricant down the length of the vaginal wall to maximize the enjoyment of the sexual partners.
Reply | Report Abuse | Link to thisThis study has no accurate evolutionary information because it does not account for the foreskin, which is not present on a dildo but which IS present on the natural penis - ergo humanity evolved with the foreskin. So studying the evolutionary purpose of the penis using an artificial penis that resembles an unnatural, surgically altered one.
Reply | Report Abuse | Link to thisAnd the prevailing theory among those who acknowledge the foreskin's evolutionary purpose says the coronal ridge's purpose is to gather the foreskin and keep it in place. And the foreskin's other purpose is to keep everything inside the vagina (vaginal secretions, semen, etc) so whether or not the coronal ridge displaces semen, everything is kept inside by the foreskin.
Gallup's
Reply | Report Abuse | Link to thisThere's one thing I have to wonder about Gallup; did he take into account circumcision?
Reply | Report Abuse | Link to this'Fraid to have to say it, but only circumcised penises have that coronal ridge description.
Gallup's theory falls appart when you take the foreskin into consideration, as the "pronounced shape" he talks about is not present in the anatomically correct penis.
The foreskin draws back and usually stays drawn back behind the corona and that hook-like shape that Gallup argues was used to "scoop out" other men's sperm? Disappears.
For Gallup's theory to be true, circumcision has to be proven to be as far back as cave men, and as widespread as it is in America. (World-wide, only about 25% to 30% of men are circumcised, and routine circumcision has only been around in America relatively recently, about a century or so, as opposed to the "thousands of years" in the Middle East.)
I would hardly call circumcision an "evolutionary" phenomenon, but a man-made, artificial one.
It's no surprise Gallup has such a view of the penis; he is/was most likely circumcised from birth, and thus that was all he knew all his life.
To summarize: The anatomically correct penis lacks the pronunced ridge that Gallup argues "scoops out" semen. It is a fallacy to assume all men in the world are circumcised simply because you are, and I'm afraid Gallup's theory has this downfall. Circumcision never was a wide-spread phenomenon, only an isolated one, limited to a specific ethnic group. The rest of the cave men had foreskins, preventing the "sperm extracting shape."
"Secrets of the Phallus: Why is the penis shaped like that?" - Answer: Because the doctor cut off your foreskin at birth. That's why.
Afterthought:
Reply | Report Abuse | Link to thisIt is a shame that Americans are lied to by omission concerning human anatomy.
Instead of showing anatomically correct genitalia, American textbooks usually portray the human penis as if it were natural to have an exposed glans without the foreskin.
Up until recently, the only description of the foreskin was something along the lines of "the extra bit of skin that covers the glans of the penis which is removed at circumcision."
Would we ever describe the labia and/or the clitoris as "those parts of female genitalia that are removed during an infibulation?"
Other words to describe the penis center around normalizing circumcision, such as the word "uncircumcised." We never call a woman with breasts "unmastectomied," or a woman with all her genitals "uninfibulated."
People don't know about the foreskin, or think about it as "extra" because that's what we are taught.
The only thing doctors are taught about the foreskin is how to cut it off.
The foreskin isn't "extra skin," it's standard equipment. The normal penis doesn't have "extra skin," the circumcised penis is MISSING parts. That's not normal.
Circumcision is a learned phenomenon. It's not "evolutionary," it is artificial. Man-made. Circumcision DESTROYS ages of evolutionary work.
Something needs to be done to update American curriculum on male genitalia; it's thousands of years old!
The foreskin is not a birth defect. Nor is it a genetic anomaly or a deformity. The foreskin is normal, healthy tissue with which each male child is born. Being born without a foreskin is the exception, not the rule; aposthia is the birth defect, and one that must be noted by nurses when it happens, like a cleft.
The foreskin is standard equipment. Circumcision is a contrived, invented, artificial phenomenon. The penis without a foreskin with the glans exposed is a beta-penis; a subversion of normal, natural male genitalia.
The main reason circumcision happens in America is that mothers in our country don't want to wash the foreskin of their sons and suffer the embarrassment of the erections that occur when doing so.
Reply | Report Abuse | Link to thisWell, these poor sexually mutilated people sure have shown the limitations of science.
Reply | Report Abuse | Link to thisThe foreskin bunches up over the coronal ridge during the outstroke of vaginal intercourse. The coronal ridge does not interact against the ribbed vaginal walls in natural sex. In fact, the coronal ridge scraping against the vaginal walls during mutilated sex is what causes dryness (it acts like a one-way pump without the foreskin bunching up behind it) and irritation to the vagina causing friction injuries. Sorry to burst your bubble.
Sure wish I lived in Europe where doctors don't give parents the right to mutilate their children's genitals. Thankfully, the rates have dropped nearly 25% in the last 4 years in the US. Way to catch up to the other 80% of the civilised world.
It is well known from the Paula Jones afair that in her
Reply | Report Abuse | Link to thisFederal court deposition she testified Clinton's to be
"Teeny weeny and bent like this"(bending her finger).
Is this a case of "The big man with a little member?"
Jesse writes his scientific stuff with a sense of humor thrown in. Very enjoyable. But I think there is one thing about the penis that he failed to mention. I explain in a story passed on to me by my engineer father:
Reply | Report Abuse | Link to thisA group of his buddies were discussing which kind of engineer helped God design the human male body.
One guy said it had to be an electrical engineer--just
look at the intricate nervious system. A second objected positing a mechanical engineer was the holy consultant--the muscle and joint structures with all the connecting ligaments and tendons is exquisite.
But a third fellow vehemently objected to the first two
claiming it clearly had to be a civil engineer--who else
would run a waste disposal line down the middle of an
amusement park?
While I agree that a lot of this article makes perfect sense, I have to wonder about my own personal experience going directly against a portion of it.
Reply | Report Abuse | Link to thisIts stated that within a minute of ejaculating your erection dissipates, and sexual intercourse becomes difficult for the rest of the day. For me however, I stay erect, sometimes for over an hour, and I have been known to ejaculate over 7 times in one day with plenty of intercourse throughout the day.
I don't know the exact mechanism that causes this, but its been like that since my youth...so I would like a more in-depth study to be done, or at very least this portion of the article to be retracted
I was just curious, why you would study and describe a circumcised penis? This is man made, not evolution! I think the whole study loses weight on that fact alone!
Reply | Report Abuse | Link to this"...the oddly shaped penis, with its bulbous glans (the “head” in common parlance), its long, rigid shaft, and the coronal ridge that forms a sort of umbrella-lip between these two parts—and work your way backward regarding how it came to look like that..."
Reply | Report Abuse | Link to thisIt came to look as you described through male-genital-mutilation, also known as circumcision. Evolution equipped human males with a foreskin-- perhaps that is where the study of the phallus should begin.
I've read a lot of comments about the importance of gang-rape in the evolution of the penis, but I'd like to point to female choice on this one. I've been with men with different penis sizes but there is no doubt whatsoever that the biggest, girthiest penis feels the best. Women also have the g-spot, and a relatively small clitoris. These seem to indicate that women have evolved to select for large penises that offer deeper stimulation. Male and female organs evolve in concert, so that the female genitalia are better able to distinguish the larger male penis. By receiving more pleasure, she is more likely to have an orgasm which increases the likelihood of fertilization. She is also more likely to have sex with a man repeatedly if she enjoys it more. Sorry boys, when women tell you size doesn't matter they're either trying to be nice or don't know any better. This leads to conflict of the sexes in which males attempt to limit female promiscuity, which if successful reduces selection for penis size. I'm curious to know if the people who evolved from sexually repressive cultures have the smallest penises, due to decreased competition. I suspect this may be true.
Reply | Report Abuse | Link to thisI can understand that you think that Monogamous men have tried to put a leash on women's sexual exploration because of cultural attitudes of european/asian's sexual insecurity or whatever, but how does women selecting the right extreme end that constitutes a smaller population being promisicuous? I never really understood this logic.
Reply | Report Abuse | Link to thisHaving a foreskin does not mean that the shape of the glans and coronal ridge is not reflected when the foreskin covers the glans on the backstroke. The foreskin is not that thick when extended over an erect penis. So the same principles will apply to non circumcised men.
Reply | Report Abuse | Link to thisIt's amazing to see the adaptation of nature to the need for evolution and gradually changing as per the need. As we can compare the shape and length of our ring and little finger with those of Apes. During the time when the need was lessened the length is gradually reducing . I think after thousand of years they may disappear like the tale of Apes. As far as the shape of Phallus is concerned it seems the phallus should act like a piston of a syringe to push the sperms from the seminal fluid towards the cervical opening.The broad portion of the phallus approximate with vagina to make the passage airtight like the piston and body of the syringe.It is very interesting to note this arrangement of the nature to the need of propogation of the human life.
Reply | Report Abuse | Link to thishere's my question then, would there then be a direct correlation between penis size and good genetics
Reply | Report Abuse | Link to thisCoincidentally, I've just been reading about penis size of the great apes in the book "Almost Chimpanzee" by Jon Cohen. Compare this information Pascal Gagneux's comparison of the penis sizes of chimpanzees and bonobos and his possible evolutionary explanations. One may argue that female chimps and bonobos are more likely than humans to have multiple partners during an estrous. Wouldn't sperm displacement be more important for them, in terms of evolutionary competition? Gagneux argues that longer penis size allows a male ape to deposit the sperm closer to the cervix... but then how does displacement figure into this, since ape penises have no coronal ridges? Or does displacement even matter?
Reply | Report Abuse | Link to thisI think it would be interesting to know whether Mike's sperm (on Josh's penis) would be 'alive' still when Josh has sex with Amy. Can we get a new article on this? This is a good topic, bring on the education!
Reply | Report Abuse | Link to thisI think it has nothing to do with the G-spot. if it were about giving more pleasure to the female, some changes might have happened to the structure of vagina, not the penis.
Reply | Report Abuse | Link to thisGallup's study has a serious flaw. The natural penis does not resemble a sex toy - it has a prepuce that moves during sex. Basically, on the pulling motion in sex the foreskin covers the glans and therefore the coronal ridge. Rather than the coronal ridge serving to remove semen, the foreskin covers up the glans in order to prevent excessive removal of lubricating fluid from the vagina during sex.
Reply | Report Abuse | Link to thisChimpanzees are plenty promiscuous, they just have different mechanisms. They have a bone in their penis (baculum or os penis) that enables them to copulate for very long periods of time. This serves to ensure that they fertilise the female and that no other male gets a chance.
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