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Cunnilingus-assisted orgasm may not be such a big mystery

This week I’ve been wrestling with a particularly large writing project which has kept me away from posting in this column. But, staring into my Twitter feed in procrastination, I spotted much outrage about a paper on the adaptive basis of cunnilingus-assisted orgasm. I had to head over to the journal Evolutionary Psychology to take a look.

The authors, Michael N. Pham, Todd K. Shackelford, Yael Sela and Lisa L. M. Welling, all of Oakland University in Michigan report the results of a simple survey they administered to 243 men in committed, heterosexual relationships. They predicted that, in their own words:

among men who perform cunnilingus on their partner, those at greater risk of sperm competition are more likely to perform cunnilingus until their partner achieves orgasm (Prediction 1), and that, among men who ejaculate during penile-vaginal intercourse and whose partner experiences a cunnilingus-assisted orgasm, ejaculation will occur during the brief period in which female orgasm might function to retain sperm (Prediction 2).

It would be too easy to sneer at the rather joyless prose, here and throughout the paper, as some popular commentators have done. And it would also be wrong. We expect scientists working on other less sensitive questions to make clear predictions that avoid imputing value or emotion. And so should it be with predictions about oral sex.

This paper is part of a rich vein of research in Evolutionary Psychology on the function of the female orgasm. In particular, it tests an idea - one enthusiastically championed by Todd Shackleford’s group - that orgasm functions to enhance the chance of conception.

One mechanism by which this could occur is by inducing uterine contractions which draw sperm toward the egg, shortening the distance sperm have to travel. This is one formulation of an old idea, colourfully called the “upsuck hypothesis”. As Mary Roach points out in point six of the video below, evidence supporting “upsuck” is equivocal.

Enjoy Mary Roach’s hilarious talk, reviewing some interesting things she discovered when writing her book on orgasm

Legion studies provide circumstantial evidence consistent with the idea of orgasm as a form of after-the-fact mate choice (“use the sperm of the guy who made you come”). Women with wealthy partners report having more orgasms. More masculine and more attractive men tend to give their female partners more orgasms.

But when would women need to discriminate among men’s ejaculates? When they mate with more than one man over a fertility cycle.

Studies on other animals, particularly insects, suggest that competition among males doesn’t stop at copulation, but continues between the ejaculates when the female mates in reasonably close succession with two or more males. And that females can differentially use the sperm of some males over others.

Studying these questions in humans is, understandably, ethically fraught, and so the evidence for sperm competition is less direct. The size of men’s testes and the volume of their ejaculate suggests that human sperm competition is important but by no means rampant.

That is consistent with the evidence that while humans show an intriguing capacity for monogamy, we are also often enthusiastically promiscuous.

So, returning to the paper in question, what do Pham and colleagues mean when they talk about “men at greater risk of sperm competition”? Did they secretly ask those men’s partners if they had been furtively mating with somebody else? Nope. Turns out their measure, which they rather clinically name “recurrent risk of sperm competition” constitutes “the mean of four variables: how sexually and physically attractive the participant views his partner, and how sexually and physically attractive the participant believes other men view his partner.”

So they asked men, four different ways, how attractive they thought their partners were. Attractive partners, by their logic, are at greater risk of having recently mated with other men.

And they found that men who rated their partners as highly attractive tended more often to have orally brought them to orgasm. Add this to another paper, recently published by Pham and Shackleford showing that men who rate their partners as attractive express greater interest in, and spend more time performing, oral sex on their partner.

Being a defender of evolutionary psychology isn’t always easy. Most research in this field is conceptually interesting, well-replicated and generally robust science. But the stuff that breaks into the news cycle and infests the Twittersphere so often tends to come from the weakest science the field has to offer. And I have to confess I find these studies among the most underwhelming I have recently read.

We biologists tend to forget that talk about sperm competition and cunnilingus-assisted orgasm induces many folks to squirm. It isn’t the squirm factor here that gets my goat.

It’s the way in which the investigator’s favoured hypotheses don’t attract the sceptical self-scrutiny they deserve. And in which alternative ideas aren’t duly considered.

And this includes considering the question from the woman’s point of view. Perhaps gathering data from women. These weaknesses play helplessly into the worst stereotypes that critics of evolutionary psychology deploy to dismiss the biological study of human behaviour.

Have you asked the womenfolk?

Evolutionary explanations for the function of orgasm tend either to see orgasm as a form of mate choice or as a by-product of the male capacity to orgasm at ejaculation. A recent review of the evolutionary literature came down in greater favour of “mate choice” hypothesis than the by-product hypothesis.

The idea that men who view their partners positively might also be more interested in pleasuring them orally doesn’t get the nuanced exploration is probably deserves. Giving and receiving of sexual pleasure is part of the complex social-biological interplay that defines relationships.

Kind men who care enough about their partners to please them sexually may also tend to view them as attractive. Men with attractive partners might work extra-hard to keep them sexually interested. Because those partners have better options should they leave.

My point is not that Pham et al are wrong. Their favoured explanation, cloaked here in the psuedo-objective language of a dry hypothesis, may well prove robust to more critical scrutiny. But there are a wealth of possible alternative explanations, some more likely than the favoured one. I trust the Conversation’s busy commentators will, in typical fashion, identify them all.

One of the things that irritates me about this paper is the way in which the paper considers one explanation among hundreds, finds evidence in support of it, and then ignores the more complex context of the behaviour. Female orgasm and oral sex are indeed rich subjects for study. I would love to know more about why not all women orgasm, why those that do do so in different ways. And why oral sex practices vary so wildly among times, places and individuals.

It is this concession of the complex, social dimensions that concedes the most interesting aspects of behaviour to those who blur it in social constructionist and post-structural mumbo-jumbo.

I wish my evolutionary colleagues would get stuck in to the much more complex social aspects of orgasm and sexual pleasure.

Double standard, much?

Bizarrely, while the function of the female orgasm gets treated as a mystery, the male orgasm seldom gets an equal workout (cue whingeing from both sides of gender political spectrum). Because male orgasm so often accompanies ejaculation, should we think of it as a mere reward for depositing sperm, motivating men to become rampant sowers-of-oats?

Likewise, I don’t see a lot of head-scratching about the functions of fellatio. And other practices that cause seed to be spilled in places other than a vagina connected to an ovulating uterus. We leave the ultraconservative nutbags to worry about these questions. So many of us stop uncritically at the assertion that sex, for men, is fun.

Why is sex fun? The answer, to so many of us, is obvious. But when Jared Diamond asked this question he exposed many far more intriguing questions that lurk beneath.

Anyone can conjure superficial answers to questions like “why do women have orgasms?”, “why don’t all women have orgasms?”, “why do men orgasm when they ejaculate” and “what is the function of oral sex?”. Good answers based on solid science are much, much harder to come by.

But that shouldn’t stop us from trying.

Join the conversation

30 Comments sorted by

  1. Dale Bloom

    Analyst

    I am now coming to the conclusion that evolutionary biology really has no benefit to anyone other than keeping evolutionary biologists employed.

    Or, evolutionary biology could be the modern day equivalent of people sitting around a camp fire at night, and making up stories and myths.

    Now men are being compared to insects in this article, as an evolutionary biologist scratches their head wondering what story to make up next at the camp fire.

    All stories and myths developed by an evolutionary biologist should be applied to evolutionary biologists first.

    So, one mechanism by which this could occur is by inducing uterine contractions in the female evolutionary biologist, which draws sperm from the male evolutionary biologist toward the egg, shortening the distance sperm have to travel.

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    1. David Collett

      IT Application Developer at Web Generation

      In reply to Dale Bloom

      "Or, evolutionary biology could be the modern day equivalent of people sitting around a camp fire at night, and making up stories and myths."

      Isn't that what you do as an Analyst? Make up stories and myths to explain the data you see?

      Could you be projecting? That is, rejecting your own unacceptable attributes by ascribing them to persons in the outside world. http://en.wikipedia.org/wiki/Psychological_projection

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    2. Dale Bloom

      Analyst

      In reply to David Collett

      I was actually a laboratory analyst.

      But, as a human, I do not want to be compared to an insect, and I don't think an insect would want to be compared to a human.

      Which makes evolutionary biology even less relevant, if that is at all possible.

      The article may make it into some gossip media somewhere.

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    3. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Dale Bloom

      There seems to be an interesting split between the progressives and those on the right about the value of this type of research.

      To the right this is a waste of time, but to the progressives this is something we want to know more about.

      The article brings out the nonsense (non-science) aspects of this study as well as the science and where science can find out more.

      To the right we should be spending money on making more money. But to the progressives the purpose of making money is so that we can have a good life - and part of a good life is sitting around the camp fire telling stories.

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    4. Dale Bloom

      Analyst

      In reply to Michael Wilbur-Ham (MWH)

      I’m not sure that insects give oral sex.

      But you could go through the Encyclopaedia of Life, and find a species you think would be good for a story or myth, and then say men are similar.

      http://eol.org/

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    5. Stuart Wigby

      Research Fellow

      In reply to Dale Bloom

      You may not want to be compared to insects Dale, but I' afraid you're pretty similar to them. Like humans, insects are animals, and consist of two sexes, males that produce sperm and females that make eggs. You share about 60% of your genes with a fruit fly. And yes, male fruit flies lick the genitalia of females prior to copulation. Much like humans, we don't really understand the function of this behaviour.

      My hunch is you think that evolutionary PSYCHOLOGY is dubious in it's benefits. I know other's who would agree, although I can see it's value. Evolutionary BIOLOGY

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    6. Stuart Wigby

      Research Fellow

      In reply to Stuart Wigby

      (whoops).... Evolutionary BIOLOGY as a whole covers a lot more ground and it's benefits are clear to anyone who cares to think about disease, pest control, conservation etc...

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    7. Dale Bloom

      Analyst

      In reply to Stuart Wigby

      So I am similar to a fruit fly.

      But previously the author said men were similar to lions, and also deer and also killer whales.

      Difficult for men to be all that at once, and I think the author is just making it all up, as a form of sensationalist journalism.

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    8. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Dale Bloom

      It wouldn't be at all difficult for you Dale if you just understood high school level science.

      What puzzles me is why you spend so much time on this website when the wonders of knowledge discovered by rationality and science seems so foreign to you.

      But your pride in ignorance goes a long way to explaining why some are so dismissive of the science behind climate change - it doesn't agree with their politics so it must be wrong.

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    9. Dale Bloom

      Analyst

      In reply to Michael Wilbur-Ham (MWH)

      There is no science in evolutionary biology, just a multitude of theories that are never proven.

      But have a look in a mirror, and see if you look like an insect, a killer whale or a lion.

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    10. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Dale Bloom

      And if you learn about science you will discover that me, you, a lion, a killer whale, and even an insect, all share a common ancestor.

      Add some physics and astronomy and you discover that we are all made from elements created in the explosions of stars - we are literally made from star dust.

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    11. Stuart Wigby

      Research Fellow

      In reply to Dale Bloom

      It's pretty easy to test an evolutionary theory actually. Evolution is just a change in gene frequency over generations. One can often make strong predictions about which genes should increase or decrease in frequency in a population under certain conditions. For example, that a gene for antibiotic resistance should increase in frequency when bacteria are exposed to antibiotics. There are numerous excellent examples of this type fo work published, if you'd care to lok for it.

      I love the what-you-look-like-in-the-mirror logic though. Brilliant.

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    12. Dale Bloom

      Analyst

      In reply to Stuart Wigby

      Here you can take your subjective pick.

      http://eol.org/

      What animal do you want to be compared to the most?

      Paralabrax auroguttatus, or perhaps Cernuella virgata, or maybe Molothrus bonariensis

      You can also make up an evolutionary biology theory to suit your preferences.

      It would just be another subjective theory.

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    13. Michael Wilbur-Ham (MWH)

      Writer (ex telecommunications engineer)

      In reply to Dale Bloom

      And thus Dale Bloom shows his total ignorance of science and leaves us all puzzled as to why he bothers to read a website which aims to promote rational thought.

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    14. Dale Bloom

      Analyst

      In reply to Michael Wilbur-Ham (MWH)

      You are very scary. You could make up a really good story around the camp fire at night.

      Like how men could turn into insects, or killer whales or lions, or whatever you think could make a good scary story.

      Try the woman has orgasms because it makes her more predisposed towards sex, and an increased amount of sex produces more children.

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  2. Michael Wilbur-Ham (MWH)

    Writer (ex telecommunications engineer)

    The theory that female orgasm helps move the sperm inside the woman to make conception more likely, and thus a man bringing his partner to orgasm via cunnilingus is done to make his sperm more likely to be the sperm which is used, must rely on the cunnilingus being performed AFTER the man has ejaculated inside her.

    I love to give a parter oral, but I always do this BEFORE I ejaculate. Is there any data which shows that I'm unusual and that many or most men perform this after they have ejaculated inside her?

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  3. Antony Eagle

    Senior Lecturer in Philosophy at University of Adelaide

    Brooks makes an apt criticism of this paper: "the paper considers one explanation among hundreds, finds evidence in support of it, and then ignores the more complex context of the behaviour." This is an instance of an epistemically flawed procedure: accept a hypothesis on the basis of supporting evidence, while ignoring the fact that the very same evidence supports a rival hypothesis even more.

    But this paper demonstrates another sort of epistemic flaw, one that is sadly apparently especially…

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  4. Pat Moore

    gardener

    Hmmm Rob, you have been quiet lately, but here's an interesting subject from the evolutionary lab's(!) slab. The 'womenfolk' don't seem to be taking the bait yet..in the interests of research....maybe it's the recent downer(!) re revelations re HPV & throat cancer...rather an orally prohibitive thought.

    Thanks for Mary Roach link, she is remarkably unabashed and candidly, refreshingly brazen, in that scientifically removed way....the pig inseminator was interesting. Need there be an evolutionary…

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  5. Tim Benham

    Student of Statistics

    > among men who ejaculate during penile-vaginal intercourse and whose partner experiences a cunnilingus-assisted orgasm, ejaculation will occur during the brief period in which female orgasm might function to retain sperm

    I don't think female orgasm continues for minutes after the cessation of stimulation, so do the men ejaculate on penetration or are they flexible enough to perform cunnilingus during intercourse?

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    1. Pat Moore

      gardener

      In reply to Tim Benham

      One word & image springs to mind...goose neck....your mother told you to do yoga for a good reason. But yes there seems to be an unexplained anomaly here unless there is a nanosecond delay between stopwatch timed procedures which all sounds so laborious & clinical unless they're talking about a group type situation? Ask your ladybirds?

      Regarding my question re possible devolution Rob...as a part of destroying the biosphere we are also kicking out from beneath ourselves the ladder which we fancy?/scientifically know? and identify to be the steps of our evolution. So with mass species extermination below us are we being left high & dry evolutionarily speaking?

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    2. Grendelus Malleolus

      Senior Nerd

      In reply to Pat Moore

      I suspect that what is being postulated is that cunnilingus-assisted orgasm occurs when cunnilingus is used to enhance arousal so that during penetrative intercourse orgasm in the female partner is more likely to be achieved. It may also refer to the substantial possibility of multiple orgasms experienced by the female partner, commencing during cunnilingus and again during penetrative intercourse.

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    1. Stephen Ralph

      carer

      In reply to Kate Rowan-Robinson

      Hi Kate

      in one sense with the world's population and the diminshing resources, we should be studying - abstainiology.

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    2. Grendelus Malleolus

      Senior Nerd

      In reply to Stephen Ralph

      Abstaining is not as effective as contraception - at least in a policy sense. It is actually nearly impossible to get people to abstain from sex (at a broad population level) but quite simple to encourage use of contraceptives.

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    3. Stephen Ralph

      carer

      In reply to Grendelus Malleolus

      I was joking ........

      b.t.w.

      the world should be thanking homosexuality for existing - there's 10% of the population not breeding - a billion less a year.

      Perhaps the lifestyle should be promoted - religions please note....

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    4. Kate Rowan-Robinson
      Kate Rowan-Robinson is a Friend of The Conversation.

      Registered Nurse/Sexology Student

      In reply to Stephen Ralph

      LOL But hasn't that been studied by most religious bodies for thousands of years?

      On a serious note I do believe we need to teach people different ways of having sex. There is so much more than just stock-standard penile-vaginal intercourse. It would solve a lot of issues.

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  6. Luftmensch

    logged in via Twitter

    Doesn't really explain the practice in same sex attracted folk though does it.

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  7. Rob Kennedy

    Co-Editor & Writer at Guys Read Gals

    What a great article; what a great website.

    What Michael N. Pham, Todd K. Shackelford, Yael Sela and Lisa L. M. Welling say, is true for me, but only because I'm old.

    OK, I'm going to be rude here, so move on if you feel this might offend you.

    I love a good lick job. I love the taste of my partner. (She'll kill me if she read this) It's like music and poetry, it's those unsaid and forbidden things that make cunnilingus feel so good. I hope no one ever removes the mystique.

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