The Evolutionary function of the hymen.

  1. What is the evolutionary significance of the female hymen? How does it aid in the survival of the human race?
     
  2. jcsd
  3. Curious3141

    Curious3141 2,970
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    Not everything must have an evolutionary significance. Human (and other animals') anatomy is riddled with vestiges. I would say the hymen is an embryological vestige, nothing more. It can be a nuisance too, imperforate hymens can cause inability to menstruate normally.

    If you want to lump cultural "significance" in with evolutionary significance, then I suppose you could say all sorts of thing about this otherwise useless membrane.
     
  4. This is a wonderful question. You will find "one" answer on page 68 of the classic book, The Naked Ape (1967) by Desmond Morris. But, do not turn first to page 68, on the journey from pp. 1-67 you will learn much about the evolutionary significance of structures-functions in the primate called Homo sapiens.
     
  5. Ouabache

    Ouabache 1,323
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    Thanks Rade for your reference. For those who don't have a copy handy, a quote follows from page 82 of Desmond Morris’ The Naked Ape: A Zoologist’s Study of the Human Animal, 1st American ed., 1967.
    He suggests that the hymen has evolved as a protective mechanism so that a woman does not to rush into intercourse until a stronger pair-bond, with deep emotional commitment, has been established with a man. From a probability standpoint, this behavior allows a woman a greater likelihood, of the man sticking around to take care of her, their child and forming a family unit.
     
  6. honestrosewater

    honestrosewater 2,330
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    Can someone explain to me how that is supposed to work? Assuming that the hymen does contribute some significant amount of difficulty or pain to penetration, the female doesn't know this ahead of time, does she? (Or is he suggesting the hymen gave rise to a kind of 'losing your virginity is painful' meme?) So he's suggesting something like this: the first time that a female starts to have sex, she experiences enough pain that she tries to stop the male, she is successful (!) and avoids having sex again until some "deep emotional involvement" (?) somehow (?) provides a reason (?) for her to put up with the pain anyway. ??
     
  7. arildno

    arildno 12,015
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    Again, a blah-blah argument from that perverter of biology, Desmond Morris. He is just silly and presents personal fantasies as scientific hypotheses.

    His project is, in essence to "explain" modern, Western lifestyles as somehow "natural" (in this case, that women has an instinct for longtime pair-bonding), even though from a historical point of view, most of his ideas can be dismissed as necessarily wrong.
    He simply doesn't know enough about the variety of human cultures and lifestyles throughout history.
     
    Last edited: Mar 5, 2006
  8. Moonbear

    Moonbear 12,266
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    It doesn't stop anyone from having intercourse or getting pregnant, thus it really has no evolutionary significance. It's just there. In many species, vaginal opening occurs when quite young, but since there's nothing detrimental to species survival about it lasting until first intercourse, there's no selection pressure for or against. (It doesn't even last until first intercourse for many women; many normal activities can tear the hymen prior to intercourse, especially in very active/athletic women).
     
  9. arildno

    arildno 12,015
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    I think it is just like our tailbone:
    Some oddity that remains from a time when it had some function.
    (My guess is for a hygienic function)
     
    Last edited: Mar 6, 2006
  10. I do think Morris' statements are a bit farfetched. I don't think there is really any evidence to support his claims about abstaining form sex because it hurts. I think that can really be tossed out the window simply by looking at the typical sexual behavior of a teenager; there is a larger percentage of teens who are having sex but don't plan on marrying the person the are having sex with.

    ~Kitty
     
  11. You are much too harsh--Dr. Morris has a Ph.D. in animal behavior from Oxford University and his major adviser was famed Dutch ethologist Niko Tinbergen. Dr. Morris was also Curator of Mammals at the London Zoo.

    As to OP--I think it a valid, and open, scientific question.

    A variety of mammal species (including humans and other primates such as lemur and chimpanzees, plus elephants, mole rats, llamas, horses) have a hymen, but a very small percent of the total number of mammals--is it just a neutral phenotype in these few species ?--I am not convinced--I suggest it is an open question worthy of investigation. Is anyone aware of a thesis that reviews the presence-absence of hymen in mammals--I am not--but this seems to me to be a valid scientific investigation and would most likely yield interesting evolutionary patterns--I suggest both neutral and selective.

    Consider that some whale species, seals, manatees have a hymen--which can be adaptive if the hymen is imperforate (complete) and thus protects vagina from water environment. Consider that in guinea pigs the hymen dissolves when female is fertile, allowing mating to occur, and then grows back to completely cover vagina--this does not sound like a neutral genetic trait to me.

    I think Dr. Morris makes a reasonable hypothesis concerning potential adaptive value of hymen in humans--but his hypothesis may well need to include a cultural aspect, not just natural selection from female not wanting to engage in intercourse. I suggest a link to group selection (e.g. inclusive fitness, kin selection, etc.)--each population (e.g. tribe) of early humans can be viewed as a separate adaptive experiment. Today it is known that > 99 % of all human females are born with at least some trace of hymen. The embryology of hymen formation in humans is well known. More than a few females have a medical condition called the imperforate hymen, a medical danger for menses. Clearly there is no adaptive value to an imperforate hymen for humans that lasts past onset of menses.

    But, consider the hypothesis that in early human tribes the percentages were reversed, only 1 % with some type of hymen, 99 % without. Most primate species do not have hymen in any form (lemur and chimp and human are exceptions, not rule for primates). I would suggest these 1 % females could have been culturally selected by the tribe (group selection) as a way to form lasting male-female pair bonding for care of offspring to insure survival of tribe (that is, the presence of a clearly non damaged hymen used by elders of tribe as indication of virginity). Females without any hymen thus selected against (by tribe)--perhaps not allowed to mate, or offspring killed (?). From anthropology it is known that some tribes today put great importance on presence of intact hymen in young females before marriage. Along this line, it would be interesting to conduct a survey of change over time in frequency and type of hymen in various cultures and relate to views about cultural importance (or lack of) of virginity.
     
    Last edited by a moderator: Mar 8, 2006
  12. arildno

    arildno 12,015
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    He is presenting a personal fantasy, nothing else. He hasn't the slightest evidence for its correctness, which is the general case about his silly claims.

    In general, socio-biology is even less of a science than psychiatry.

    As a note, I couldn't care less if he were a multiple Nobel prize winner as long as his ideas are trash.
     
    Last edited: Mar 10, 2006
  13. Well, E. O. Wilson would certainly get a good laugh from this statement. So, your "silly biologist criterion" thus links D. Morris with E. O. Wilson--thus how silly for E. O. Wilson to have been awarded two Pulitzer Prises and position as distinqiushed Professor at Harvard University mostly for his philosophy that links socio-biology to human nature. I find all your hand waving about silly biologists as providing nothing of value to this thread. If you have a logical argument about the OP, please do present it.
     
  14. arildno

    arildno 12,015
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    Remember who's doing the hand-waving here:
    Desmond Morris with his totally unsubstantiated claim.
     
  15. arildno

    arildno 12,015
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    Hmm..so according to D. Morris, once the rupture of the hymen occurs, the female gets scared and stops having sex until she finds a male she wants to spend her life with?

    Sorry to enlighten you, but that is patently false.
     
  16. Sorry to disappoint: you have most certainly not enlightened me.

    I may be recalling Morris's hypothesis unclearly, as it is some time since I read it. However, your rendition of it does not match my recollection. Once the pain associated with the rupture of the hymen becomes generally known it acts as a disincentive for casual sex by pubescent females until they have acquired a mate who is likely to stick around.

    While that is certainly not a proven mechanism, it is certainly a plausible mechanism. Your erection (pun intended) of a strawman argument, do not detract from that plausibility.

    So, please be good enough to explain what is patently false about the correct version of Morris's hypothesis.
     
    Last edited by a moderator: Mar 12, 2006
  17. arildno

    arildno 12,015
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    Ask any woman of your acquaintance if they abstain from sex out of fear from the pain associated with hymen rupturing.
     
  18. arildno

    arildno 12,015
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    I have already mentioned one possible explanation of the evolutionary advantage of the hymen that seems a lot more plausible than the silliness forwarded by Morris:

    A hygienic function.

    If it is really necessary to spell it out, okay then:
    1. It is known that inflammation of the uterus may cause infertility in females.

    2. It seems probable that a (partial) closure of the vaginal opening as the hymen represents reduces the inflow of bacteria, and hence, reduces the risk for infection inside the female.

    3. In a species like homo sapiens, where the pre-pubescent and pre-sexual phase is extraordinarily long compared to other species, hindrance of severe vaginal infections prior to the time of sexual maturity would have an evolutionary advantage compared to that group of girls which are more exposed to contracting infertilizing infections before they had the chance to reproduce.

    Hymen retention seems an easy way to ensure that most girls will have their potential fertility undamaged until pubescence.
     
    Last edited: Mar 12, 2006
  19. OK, an hypothesis for sure, but please explain how "partial" closure protects reproductive organs of female against bacteria, fungi, etc. that have size much, much smaller than the hymen opening ? It just does not follow. Your hypothesis only makes sense if the hymen in humans was completely closed (e.g., imperforate) as found for example in whales, but the facts are the exact opposite, such condition is very rare in humans. Please understand, I have no time for or interest in name calling on this thread topic (e.g. silly this or that Ph.D. level biologist)--yet I find it fascinating that my recent search of > 3000 peer reviewed journals in science and not a single paper on the topic of evolutionary significance of hymen in mammals ! Why is this not a topic of interest ?
     
  20. arildno

    arildno 12,015
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    A very good counter-argument to my theory.
    As for whether my theory makes sense or not, it is at least falsifiable (by making an empirical study on the hymen's effectiveness as a barrier).

    That cannot be said about Dr. Morris' hypothesis, since he and his followers reject outright as a valid complaint that there are NO women at all who has abstained from sex out of fear of the pain associated by hymen rupturing.
    By retreating into their cosy, little realm defended by unfalsifiability, they have cut themselves off from the world of science.
     
  21. arildno

    arildno 12,015
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    As for other SCIENTIFIC hypotheses concerning the retention of the hymen (in contrast to Desmond Morris' unscientific, ideology-driven drivel),
    I'm sure there are plenty of good ideas about:
    Here's a couple of others:

    1) The presence of the hymen might preserve the proper level of humidity in the vaginal tract, so that dryness and ensuing risk of infection does not occur, i.e, maximizing the number of girls reaching puberty without infertilizing infections.
    This is, at least, a falsifiable theory.

    2) Since the female will always know whether a child is her own or not, but the male does not have that type of certainty, a (almost) sure proof of the virginity of a female might be enticing for a male who wants to ensure himself he's to raise his OWN children, rather than some other male's.
    Thus, the hymen may have been retained in the female as yet another feminine allurement of the male, i.e, a stratagem to get the male she wants "hooked". This theory does have some empirical support, in that male preoccupation with the virginity of prospective brides is historically well-attested, and some contemperaneous accounts seems to suggest that straight males have a peculiar fascination of, and attraction to, female virgins.
     
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