A Chance to Read About Penises On Your Lunch Hour (Without Getting Fired)


Well, hopefully your bosses appreciate your yearnings for scientific knowledge. Because, did you know that scientists have only recently started asking themselves why the penis evolved the way it did? (Which is to say, the average human penis is approximately twice the size of chimps.) Probably because it’s harder for researches to get a grant that has “Objective: Looking at wangs over the last million years” written at the top. But at least one scientist, Gordon Gallup, is looking at the penis for what it truly is: a “tool” that, amazingly, is excellent in both form and function. Scientific American:

Gallup’s approach to studying the design of the human penis is a perfect example of of “reverse-engineering” as it’s used in the field of evolutionary psychology. This is a logico-deductive investigative technique for uncovering the adaptive purpose or function of existing (or “extant”) physical traits, psychological processes, or cognitive biases. 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 that forms a sort of umbrella-lip between these two parts—and work your way backward regarding how it came to look like that, the reverse-engineer is able to posit a set of function-based hypotheses derived from evolutionary theory.

And sorry gays, but when it comes to evolution, scientists will be looking at how the penis works with the vagina, not an anus. Despite our lobbying efforts.

Magnetic imaging studies of heterosexual couples having sex reveal that, during coitus, the typical penis completely expands and occupies the vaginal tract, and with full penetration can even reach the woman’s cervix and lift her uterus. This combined with the fact that human ejaculate is expelled with great force and considerable distance (up to two feet if not contained), suggests that men are designed to release sperm into the uppermost portion of the vagina possible. Thus, in a theoretical paper published in the journal Evolutionary Psychology in 2004, Gallup and coauthor, Rebecca Burch, conjecture that, “A longer penis would not only have been an advantage for leaving semen in a less accessible part of the vagina, but by filling and expanding the vagina it also would aid and abet the displacement of semen left by other males as a means of maximizing the likelihood of paternity.”

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.

There’s more.

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  • Samwise

    you know… while interesting and all… i dont think I want to be eating lunch while reading this.

  • huh?

    Why even put up al these facts? It only supports those who maintain an argument that “being gay” is unnatural because the penis and the vagina were made for each other, and the penis has no business in the anus. thus being unnatural.
    “men are designed to release sperm into the uppermost portion of the vagina possible”
    yeah, duh. straight men, right? any gay science out there?

  • QICM

    @huh?: “Huh” is right. I don’t think you need to deny the reproductive capacity of human beings, or ignore it, in order to support gays, or to think that homosexuality is perfectly natural. It isn’t exactly like oral and anal sex and mutual masturbation are unheard of among opposite-sex couples.

  • John Santos

    What a happy looking penis!

  • SaintCahier

    @HUH?: Attempts to find justification to queerness in natural sciences are misguided, I think… Why would gayness be more justified if it were a natural phenomenon than if it were a social one ?

    The fact the penis were designed to the vagine doesn’t in princple forbid us to pursue creative uses for it, does it ?

  • eagledancer4444

    Hey–remember me? Family Therapist and Sex Researcher here…it isn’t ONLY about reproduction. Some of the most recent research (which I think also showed up on Queerty) was how male chimps gave meat/food to females when they weren’t “in heat” which is being perceived as a bonding mechanism that may “pay off” with getting laid later on. When I was at a Board of Directors meeting for the Sexuality Information Education Council of the U.S. (, we had an anthropologist named Helen Fisher come in to present on her research (she got a lot more press for her work on the “chemistry of love,” looking at neurotransmitters) on Pygmy Chimps, or known more often these days, as Bonobos. She explained in her field work, it was common to see the same varieties of sexual behavior among the Bonobo as in humans, with the exception of whips and chains, most likely because it’s so hard to get whips and chains in their habitat. These behaviors include same-sex activity, orgies, and prostitution. Older male bonobos would offer sugar cane to females in exchange for sex.

    After she finished, I went up to her and asked if she ever saw a male bonobo offer sugar cane to another male in exchange for sex. She replied she saw it all the time, but didn’t mention it because often audience members were uncomfortable to find that out. This, by the way, is why it’s taken so long to actually have the same-sex slant available. There was an unwritten ban in the American Anthropological Association around cross-cultural same-sex issues. As a grad student, you were told if you ever tried to publish anything on the subject, you’d never be offered a job. The ban was broken with Herdt’s work on New Guinea males, where 100% of males had same-sex experience as part of their initiation rituals.

    Anyway–take a look at the video below–it’s not in English but you can just watch with the sound off if you’re English monolingual. Sit through a bunch of horny rams and buffalo humping each other to get to the bonobos.

    A) Notice the bonobo doesn’t need to be in heat to hump. There is a female with child “getting it on.” While nursing, primates (including humans) don’t tend to be fertile.
    B) Notice the use of sugar cane to get attention…makes you wonder if an alien Anthropologist would watch a male human give a female human a box of chocolate and write down “prostitution.”
    C)The other interesting thing (to me at least) that you can see in the vid–the bonobo is the only other primate besides the human that will do sex face to face.

    The point–the penis may be extremely well designed to impregnate, but it’s also been well designed to urinate. It’s multifunctional. Regardless of whether the penis is being pleasured by a vagina, a mouth, an anus, or a hand (or an apple pie) one of its functions is also to be stimulated. To see it as ONLY functioning to impregnate is very limited. Just as limited as expecting female humans to give up sex once they’ve gotten past the fertile stage of their lives.

  • eagledancer4444

    sorry–also meant to add the importance of social bonding that sex can bring about, whether it’s between male/female, female/female, male/male, or other genders. Fisher (the anthropologist I mentioned) when she puts on her neurotransmitter hat–might suggest the body and mind connection. There’s no question there is also some sort of physical expression of the emotional bonding, so it isn’t an “either/or” situation of it’s biological or it’s social. The social will have a component of the biological.

  • paul-e-wog

    If I was reading this in my formative teen years (instead of now at 37 years old), this article would have made me celibate for the rest of my life.

  • Monica Roberts

    How insensitive to those of us who have had our male genitalia snatched off and a artificial pussy installed.

    Where do WE fit into this biology. It is time you faced up to your OGP (original genital privilege).

    Sigh, I guess I will have to give another class on Tranniez 101 up in here.

  • Blucky

    I think it’s less about female promiscuity than about gang rape. In the olden days, when you conquered a city-state, your soldiers would “sack” the city. This entailed killing the men and raping the women, sometimes dozens, hundreds, or thousands of times.

  • james p. p.

    I think this is interesting. from an evolutionary standpoint, we have to think of the male and female parts going together as the “natural” means of continuing our species. as society grows and changes, the progress of science and technology let’s us have more options than what is “normal” or “natural”.

    case and point, under Natural Selection a woman who’s eggs do not drop cannot conceive or reproduce. 50 years ago, she would have no choice but to go childless and thus her bloodline would cease. now we have various different options for her to conceive a child… (someone who takes this progress too far? Octomom). Natural selection would weed out women with no maternal instincts, men with slow sperm, the obese, etc.

    but now, as INDIVIDUALS, we are open and allowed to have our individual choices about (1) making ourselves mentally happy and (2) choosing our own way of furthering the species. a lesbian can get impregnated and raise a child with her partner – option. a gay couple can adopt – option. a female to male transgendered person can get pregnant and give birth to a child (twice) – option.

    progress in science and in mental evolution begets individual choices that not only allow us to live happy, but also help the furthering of our species as we are no longer dictated by the simple grunt “penis in vagina” mechanics of reproduction.

    how will this evolutionary shift change our physical being? we will have to wait several hundred years to find out…..

    (SIDE POINT: sex is not unlike violence. violence is also “natural” – whether it’s the supernova in space or allowing retaliation killing in the bible, or modern day war. but as individuals, natural violence is no longer acceptable. we cannot beat up/kill each other as the “natural” order in the animal kingdom. we have progressed passed the “natural” inclinations of things, passed laws to protect us as individuals, and yet this is considered a GOOD thing. why should sex be any different of an evolutionary process?)

  • eagledancer4444

    Homosexuality as a “normal” thing didn’t make sense to some evolutionary biologists (breeding is the ultimate goal…dna is like beer–both invented human beings as a way of getting from one place to another) until one steps back and looks at a larger picture of passing on genes rather than on a one-to-one basis and how genes survive in a troop/pack/society.

    For example, I’m American Indian. Many of our traditional nations have a history of what we now call “Two-Spirit” people. The term indicates an alternative gender role. (Incidently, in some communities there are more than 3 genders–and in some NW communities, as many as 8 genders)

    In this situation, a Two-Spirit person may not sire or conceive a child, but may take on a caretaking role the way many contemporary non-Native gays and lesbians make incredible uncles and aunts. The non-reproducing individuals will share the genes of siblings, which means not only a percentage of the shared genes are passed on, but the survival rates of the nieces and nephews increase dramatically. Not only in Native American groups, but in many other traditional communities, children are raised within an extended family rather than the very recently eveloped nuclear family structure.

    Just so, many “high status” individuals (this was true of some of the better known “Chiefs” many non-Natives have read about) had multiple spouses. This didn’t have the same structure of a “harem” but reflected the responsibility of someone in a leadership capacity to provide for needy members of the whole group. Multiple spouses meant being able to process food and necessities (clothing, for example) and have enough “extra” to help out those who could not provide for themselves because of age or injury. A Two-Spirit person would often be a “second” spouse, since the ephasis on the “first” spouse would be on–tah dah! reproduction. In other words, this isn’t an “either/or” binary simplicity of reproducing or not, but is more complex. In a number of traditionally based societies, once an individual had reproduced, then he or she (or alternative gender) could focus on a partnership/relationship that was more desired. This is what we see in a lot of contemporary gay/lesbian people who were heterosexually involved, and are now divorced and in a same-sex relationship with their children.

    To put it in a way some reader here might understand, when I congratulated an ex on his marriage, he told me I could have always had a husband if I had wanted one. I replied, “Oh, I’ve had plenty of husbands…they just weren’t mine.”

    If you focus on the need of the genes to reproduce themselves, then it’s logical this doesn’t automatically mean it’s going to be the same combination of genes each time. In other words–if it’s your genes, maybe there will be more reproduction with multipole partners. That’s why so many primal communities are matrilineal. It doesn’t matter who the father is in these societies, since siblings share the same mother–and that’s never in doubt.

    Also remember in traditional societies another function of having a child is not just to pass down the genes, but to save your own ageing ass. In many traditional communities, a child is a type of “social security.” This is someone who will provide for you when you become an elder. Parenting tends to “skip” a generation, where grandparents raise grandchildren and parents have the “bread-winning” responsibility to provide for both grandparents and the grandchildren. In many Native American languages, “cousin” actually is the same word as “sibling,” since their relationship to the grandparents is the same. Indeed, the relationship to their aunts and uncles is also the same. Does that make sense? Think of a circle that contains “siblings” which includes first cousins. Now draw a larger circle to encompass this one and mark on it “grandparents/granduncles/grandaunts/clan elders (who may not be biologically related, but are socially related…godparents would also fit in here). There are also what anthropologists call “fictive kin.” Maybe you grew up with an “Aunt Betty” or an “Uncle Carl,” who wasn’t “really” related to you, but was the best friend of your mother or father. These individuals can have tremendous influence on the socialization of a chlid. But you can see where they don’t show up very easily when doing a geneology chart.

    Among a number of Native peoples, there are “seven sacred ceremonies,” one of which is “adoption.” If you didn’t have your own child–one you sired or conceived–or a niece or nephew, then you might be “assigned” an orphan, so both of your needs on a social level could be met. In my mom’s community, for example you’re not considered to be a “true” adult until you’ve parented. It’s irrelevant if you’ve parented your “own” child–helping parent a niece or nephew, or a clan relative will do just fine. Is this getting “too far away” from the original gene consideration? In my mom’s language, we have 28 different relationship terms to align us in our identity. For example, we distinguish between a maternal and a paternal grandmother. In English, there simply one word for both.

    I don’t want to go iinto violence as a “natural” issue at this time, but in many historical Native groups, after a conflict was over, “enemy” children (and often adults) would be integrated within the surviving/”winning” community. If you are raised with the concept adoption is a sacred ceremony, and the worldview that all is related, then it becomes easier to conceptualize membership within a larger context. More recent biological research amongst Native American groups would indicate a much closer and direct genetic connection between groups that are geographically distant. Perhaps this would indicate a more successful gene survival mechanism lol.

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