The Evolutionary function of the hymen.

[misogynisticfeminist]

What is the evolutionary significance of the female hymen? How does it aid in the survival of the human race?

 

[Curious3141]

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.

 

[Rade]

What is the evolutionary significance of the female hymen? How does it aid in the survival of the human race?

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.

 

[Ouabache]

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.

Another related feature, and one that appears to be unique to our speices, is the retention of the hymen or maidenhead in the female. In lower mammals it occurs as an embryonic stage in the development of the urogenital system, but as part of the naked ape’s neoteny it is retained. Its persistence means that the first copulation in the life of the female will meet with some difficulty. When evolution has gone to such lengths to render her as sexually responsive as possible, it is at first sight, strange that she should also be equipped with what amounts to an anti-copulatory device. But the situation is not as contradictory as it may appear. By making the first copulation attempt difficult and even painful, the hymen ensures that it will not be indulged in lightly. Clearly, during the adolescent phase, there is going to be a period of sexual experimentation, of ‘playing the field’ in search of a suitable partner. Young males at this time will have no good reason for stopping short of full copulation. If a pair-bond does not form, they have not committed themselves in any way and can move on until they find a suitable mate. But if young females were to go so far without pair-formation, they might very well find themselves pregnant and heading straight towards a parental situation with no partner to accompany them. By putting a partial brake on this trend in the female, the hymen demands that she shall have already developed a deep emotional involvement before taking the final step, an involvement strong enough to take the initial physical discomfort in its stride.

 

[honestrosewater]

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. ??

 

[arildno]

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.

 

[Moonbear]

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).

 

[arildno]

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)

 

[misskitty]

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

 

[Rade]

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

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.

To others

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.

 

[arildno]

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.

 

[Rade]

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

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.

 

[arildno]

Remember who's doing the hand-waving here:
Desmond Morris with his totally unsubstantiated claim.

 

[arildno]

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.

 

[Ophiolite]

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.

 

[arildno]

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

 

[arildno]

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.

 

[Rade]

I have already mentioned one possible explanation of the evolutionary advantage of the hymen ...A hygienic function..

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 ?

 

[arildno]

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.

 

[arildno]

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.

 

[selfAdjoint]

Well arildno, you finally got around to my hypothesis (your #2). I wasn't going to post it for fear of getting into a flame war with you over ideology.

In fact, of course human males have no inner need to stay around and help raise the kids, and giving them an ego/property right does tend to enhance that behavior, whatever one thinks of patriarchal cultures.

 

[Moonbear]

With regard to #2 in post #20, you'd have to show that men, as well as males of other species, actually bother checking for an intact hymen before engaging in intercourse to demonstrate that is involved.

I actually think the hygienic barrier function makes a bit more sense. Not as the hymen currently exists in women, but in an evolutionary sense. Since many species do have a completely closed vagina until reaching sexual maturity, it could just be that such selection has been relaxed in humans long enough that "imperfect" hymens were not selected against. That some girls are born with imperforate hymens, even if that's currently a bad thing, that may not have always been a bad thing, especially if something between the two current variants existed in ancestral humans.

When thinking about the evolutionary role of a particular feature, it's good to look at the variant forms present in other species and take a more comparative approach than to try to cobble together some hypothesis based solely on the modern-day function, which it may not have. Given the wide range of variation among various species, from the partially closed structure in humans to the structure in many rodents that is closed until puberty, to the structure in guinea pigs that opens and closes with every ovulatory cycle, it would indicate that any function it did have is not very important for survival in the modern world, and that there hasn't been much selection pressure for it in a very long time for such variation to exist.

One could also speculate it is the other way around, that it has never had a function, and is tissue that is "left over" during development of the reproductive tract , and that it would be better for the survival of the species not to have it, but as long as it is not impenetrable, it's not going to limit reproduction, thus was never selected against. Perhaps no different than the webbing between the fingers of the embryonic human that is supposed to be gone by the time the baby is born, but once in a while a baby is born with webbed fingers, except in the case of the hymen, it became more common because there was no social selection against it (by the time a potential mate discovers it, it's too late to opt to not reproduce).

 

[arildno]

Well arildno, you finally got around to my hypothesis (your #2). I wasn't going to post it for fear of getting into a flame war with you over ideology.

In fact, of course human males have no inner need to stay around and help raise the kids, and giving them an ego/property right does tend to enhance that behavior, whatever one thinks of patriarchal cultures.

Have no fear!
I hope I made it clear that what I dislike immensely with Morris' hypothesis is that
a) he does not bother to check whether there is empirical support for his hypothesis

b) That he cannot possibly talk about real humans, since that would imply that actual women abstained from sex out of fear from the pain of hymen rupture (which is not the case)

I find Moonbear's criticism very good, and to the point.

I'm not too sure whether this issue is unambiguously resolvable.

 

[Rade]

b) That he cannot possibly talk about real humans, since that would imply that actual women abstained from sex out of fear from the pain of hymen rupture (which is not the case)

Do you have the reference to the publication where this was statistically shown ? --I would like to see the form of the questionnaire that was used to reach this scientific conclusion. Clearly, if such a finding has been published, then Morris's hypothesis has been falsified--if so, I really do not understand the above statement that the hypothesis of Morris can never be falsified--seems to me you have knowledge of the study that has done so.

 

[Mk]

I think arildno has got it right. Up till now, I've always spelled it "arnildo." I hope you didn't mind too much. lol sorry. I thought it was spelled like that.

 

[SciFiGuy]

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.

While Morris's explanation has issues, you've just demonstrated some pretty severe bias of your own in your critique of Morris's bias.
It is in the best evolutionary interest of women to maintain a long-term pair bond. Clearly, pair-bonded women have access to more resources to raise their children. However, women who are bonded to the father of their children are better off than those who practice serial monogamy. Numerous studies have shown that step-children are more likely to be abused and eve killed than natural children. Step-children are also less likely to be financially supported - I seem to remember a massive gap in the percentage of natural children whose parents funded their college education versus step-children.
I'd also challenge this idea that it's all about being Western culture to talk about long term pair bonds - most cultures have marriage. Most cultures let men divorce, or take additional spouses, but not women. Interestingly, this fits well with men's ability to function as r-strategists, where women cannot (as effectively).
So, while Morris MAY be full of it, his explanation is based on real female optimal reproductive strategy, and deserves to be mocked only for the faults it actually possesses.