Skepchick Quickies, 9.7


Jen is a writer and web designer/developer in Columbus, Ohio. She spends too much time on Twitter at @antiheroine.

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  1. After reading about the evolutionary mystery of the female orgasm ‘baffling biologists’. I learned scientist have studied ‘orgasmic function in thousands of twins’ which has lead to a ‘furious scientific debate’. It turns out, ‘self-reported surveys aren’t methodologically airtight’.

  2. I’ve read Lloyd excellent book on the female orgasm. I cannot access the original publication of the twin study but described as it is, I have trouble understanding even the rationale of their study. How is this study supposed to test one of the central tenet of the by-product theory ?

    1. If opposite gender twins (who share between 25 and 50% of their mother’s DNA) were to report similar numbers WRT orgasm, then you could extrapolate that the female orgasm is likely a byproduct of the male orgasm (for which their is a clear and obvious evolutionary advantage).

      But they don’t, so that conclusion cannot be made …

  3. Jen: It looks like the third link, “7 tools to stay young forever (…in theory),” is pointed to the wrong article. Granted, it’s a quite interesting article nonetheless, about the suppression of science done in the name of oil interests.

  4. Re: the female orgasm study – why study twins, rather than siblings? Opposite sex twins aren’t any closer, genetically, than different aged siblings, are they? Or am I wrong that identical twins are always the same sex?

    1. We look at twins mostly because it is the best way to keep the environment constant. Even small changes in maternal diet/health during pregnancy can have huge effects on the baby, and between two siblings that will not always be as constant as it is between two twins.

      The basic idea behind twin studies for genetics is precisely that identical twins share all of their DNA while fraternal twins share only half on average (like you said, just like any other sibling). But both identical and fraternal twins share uterine environment and were probably raised together. So if something is genetic, identical twins will share it more often than fraternal twins. But if something is environmental, both kinds of twins will share it at about the same rates.

      The study asked two questions: first, to what extent is female orgasm genetic, and second, to what extent is female orgasm predictive of other traits, like being married or financially successful or liberal. The fact that we’re talking about twins is relevant only for the first question. The second question is independent of the relations between subjects.

      (Interestingly enough, it turns out that female orgasm is somewhat genetic in nature, but it doesn’t track with the other measured traits. That’s a problem for an evolutionary explanation because if having more orgasms doesn’t mean having more kids, then it’s not selective so much as lucky.)

    2. The identical twins (which are always the same sex, as they’re the result of an already fertilized egg splitting apart early on IIRC) are good for finding things that are caused by genetics (a high correlation between the siblings would indicate a genetic component).

      The study of non identical same-sex twins is a good way of testing the nurture component (as the twins aren’t genetically identical, but their upbringing usually is similar enough).

      As for the opposite-sex twins, I think that’s as close as you can get to the above two situations with two people of a different sex.

  5. The drive for mutual sexual satisfaction in both partners necessitates that the intercourse be prolonged and emotionally intimate. Such intimacy promotes social bonds and enhances the survival rate of the children. Problem solved. You’re welcome.

    1. The different pair-bond hypothesis of the female orgasm are quite well debunked in Lloyd’s book : one of the problems of these hypothesis is that they suppose that female always orgasm during penetrative intercourse which is simply flat false.

      1. I appreciate the information, but that’s completely not my point – which was about the fact that mutually satisfying intercourse promotes intimacy, which in itself helps to create an emotional and social bond. I didn’t say anything about penetration.

        1. Ok just to understand : are we talking about the potential adaptative value of intercourse or orgasm, here ? And does a “mutually satisfying intercourse” entail orgasm for women ?

          1. Look, I don’t know why this is so hard for you – it’s really pretty obvious. We are one of very few species that doesn’t need a mating cycle in order to copulate. As higher social animals, the drive to copulate is part of the complexity of our culture. And in fact, the very humanity that we share is enhanced by sexual intimacy – the benefits are a type of emotional closeness that helps to preserve not just our genes but our place in society. We are generally more confident, less frustrated, and feel more emotional security from having a sexual partner. Anything that prolongs the act and increases the physical pleasure of either partner is going to be selected for – I don’t know how you can escape that logic.

  6. I remember watching some show on the History channel late one night that talked about human sexuality. They had taken a special camera and inserted it into a woman’s vagina while she was having sex and when she orgasmed you could see the cervix dipping downwards and into the semen. The narrator and the researcher on the show pretty much claimed that that was the purpose of female orgasm.

    I think it was a BBC show. I wish I could remember what it was called.

    1. I saw that, and the same conclusion clicked for me. THAT makes perfect evolutionary sense. Women orgasm to increase the chances of getting pregnant. I wonder if anyone could do a study on that hypothesis.

      1. From Elisabeth Lloyd’s FAQ on her book :

        Q: “I have seen video on the discovery channel of what happens during a female orgasm. The cervix dips into the semen pool and sucks in the sperm into the womb, hence helping to reproduce. So what are you talking about?”

        A: Don’t be sucked in. This is not actually a film of “sperm upsuck” into the cervix, as the narrator claims in the film. This seems to be a case of showing one thing, and describing another, according to an endowed chair in sexual physiology at a top research institution who was involved in the production of the show. The cervix does move during the uterine contractions of orgasm, and thus can be seen here moving further into the ‘tenting’ that develops at the end of the vagina just before orgasm. So you see the moving cervix; the narrator supplies a description that is not verified – saying that the cervix is sucking the semen in, at the same time that you see it dipping.

        If that film really had shown sperm upsuck, as it said – or, in fact, anything at all suggesting a correlation involving orgasm and fertility – it would have created a sensation in the world of sex research and evolutionary studies. People have been trying unsuccessfully to demonstrate sperm upsuck since 1950 (Lloyd 2005, pp. 179-219), and such a decisive finding would have been celebrated. The film was deceptively narrated, and unfortunately the audience had no way of knowing that it did not show what it purported to show. I cannot estimate how many emails from around the world I have received telling me that I am ‘stupid’ or worse, based on this deceptive TV show!

      2. I saw this documentary, it was on Discovery channel under curiosity day.
        i think the actual video of the inside of the vagina was a CGI animation rather than actual camera placed there.

        As they explained it it made perfect sense. That the contractions men and women share at the moment of the orgasm will push the sperm for males and will have a sucking effect for females.
        They actually showed some compelling evidence for that.
        But now after reading the comment above im conpletly baffled…

        Neh sometimes being a skeptic can lead to a boring truth.

    2. Despite having been debunked already, that theory doesn’t explain why female orgasm would therefore evolve to be pleasurable, or why it would not occur in all women, or every time.

      In fact, from an evolutionary point of view, women who did have that contraction occuring wouldn’t necessarily need an orgasm, whereas women with whom it doesn’t happen would need the experience to be enjoyable in order to increase the amount of intercourse and the chances of conception.
      As such, this theory doesn’t really explain much …

  7. As a lady who enjoys the heck out of sex and has never had a problem orgasming, I have to ask, must the female orgasm have a purpose? I mean, sure, just about everything else we’ve classified and studied has some discoverable function. But would it be so bad if this didn’t have some ultimate end beyond just feeling freaking fantastic (and maybe being a source of stress relief)?

    I suppose I’m just hopeful.

    Anyway, I’d be much more pleased to see a bunch of *women* scientists studying this. As it is, the study has an odor about it, an acrid mustiness of trying to tease out the “real” reason it’s important women enjoy themselves during sex. And if they do find a reason, the female orgasm will just be pigeonholed even further; this time not as some ineffable mystery, but as something just as weirdly sacred for its potential connection to some delicate and mundane process.

    Can’t we just agree that female orgasms make the world a better place and leave it at that?

  8. There’s a book I read that hypothesized that the female orgasm is the way it is to encourage multiple couplings in a single mating. The book’s argument was that human sexuality is inherently promiscuous (more like chimpanzees and bonobos), citing also examples of hunter-gatherer cultures that are highly open sexually. The notion that humans are natural monogamists is, according to the authors, an artifact of agricultural civilization and the hang-ups about sex and property it created.

    The argument regarding the female orgasm goes like this: genital and penis size in human males indicates a sperm-competition strategy in mating. Our reproductive organs are far larger than those of monogamous or polygnous species, like gibbons (monogamous) or gorillas (polygnous). These species mate only to reproduce, and males ensure their legacy by attracting the attentions of a single female or controlling a harem of females.

    Humans are different. Like chimps and bonobos, we have sex for fun and for socialization as well. Adapted, as we are, for small tribes in which hierarchies would destroy social cohesion, sexual competition has to occur in another fashion. That is through sperm competition, which occurs when multiple men have sex with the same woman. Both the volume of human ejaculate, as well as the chemical composition of pre- and post-ejaculate, indicate that we are evolved for sperm competition. The slow-burn of female orgasm is to encourage human women to have sex with multiple partners, ensuring that sperm competition takes place. Though my explanation is long-winded, I find the concept an elegant solution.

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