The female orgasm: An evolutionary adaptation, or a happy accident?

The female orgasm is a funny thing. We’re never taught about it in school, no one ever brings it up in conversation and so girls everywhere must inevitably rely on the wisdom of film and TV to gain information on this elusive phenomenon, from which it becomes clear that women consistently have an orgasm approximately 1-2 minutes after a man climbs on top of her and moves back and forward a bit (you only have to presume his penis is involved somewhere, but this is all guesswork since we never see that, either). Then when it comes to actually losing your virginity, you are genuinely confused as to why you weren’t left trembling and glowing with pleasure and desperately wondering how anyone can enjoy having a penis anywhere near them.

See? She’s having a great time.

But even once we’ve cracked what the reality of this ultimate height of female sexual pleasure actually is, there is still a significant air of mystery surrounding the female orgasm, particularly for evolutionary biologists. This is a two sided debate: is the female orgasm an evolutionary adaptation in its own right, or is it just an evolutionary by-product of the undeniably functional male orgasm?

The by-product hypothesis

It’s fairly easy to see how the male orgasm can be explained away as being an evolutionary adaptation. Males tend to (but not always, mind) orgasm as they ejaculate. Ejaculation = the transfer of sperm into the female’s reproductive tract, thus increasing the likelihood of sperm meeting egg and making a baby and BOOM you have passed on your genes. Darwin would be proud, you fitty. Orgasm is universally accepted to be a totally sweet experience. All sorts of lovely chemicals are released in your brain and you generally feel pretty awesome. If you orgasm at the same as you ejaculate, the chances are that you are going to want to repeat that whole process again because it feels GOOD. This will probably lead to more babies. You see how this works.

The female orgasm is not so easy to explain in its own evolutionary right. Orgasm is not required to release an egg or for fertilisation. Therefore some researchers argue that the female orgasm is simply an analogous case to male nipples – a result of the shared ontogeny between males and females at the early stages of fetal development. Nipples are obviously very important in females of all mammals for milk production, and so develop in both sexes JUST IN CASE. After all, most females reach orgasm through (masturbatory) clitoral stimulation, not through penile penetration, and the clitoris can be viewed as the sensitive head of an underdeveloped penis, since the genitals begin to develop homogeneously before a sex is assigned to any fetus.

It does look suspiciously like a cock.

This all seems quite logical, I guess we can all just accept that the female orgasm is, in the words of biologist Elisabeth Lloyd who wrote a book on the subject, a “happy accident”.

BUT WAIT!

There are some hypotheses that may contradict this by-product hypothesis (there are quite a lot out there, I’ll just give you a taster).

The “upsuck hypothesis”

This hypothesis has actually been largely discredited now, but with a name like “upsuck” I couldn’t help but discuss it just a little bit. This hypothesis hypothesises what it says on the tin, really. It is the theory that a female orgasm triggers funky muscle contractions and uterine suckage (nom), and that these help deliver the freshly-ejaculated sperm up the reproductive tract, closer to her eggs. M’aawwww, isn’t that cute? (By the way, it’s worth noting that this hypothesis apparently came about in the 1960s when a doctor reported how his female patient climaxed so hard that her uterus sucked the condom right off her lover’s penis and got stuck in her cervix. I have no idea if that’s true, but I happen to think that’s a pretty awesome yet terrifying anecdote). So (30 years later – you can’t rush science) this intriguing hypothesis was tested with an equally brilliantly-named technique: the flowback method. Seriously, I love this shit, how can anyone not want to be a scientist? Anyway, this involves a man ejaculating into a lady who may or may not have had an orgasm (the times of each orgasm were recorded by each couple) and collecting the the semen within the vaginal flowback (I’m sure you worked this out yourself – but that’s the stuff that emerges from the vagina a few hours after sex).

The researchers concluded that when a woman climaxes up to 45 minutes after her lover ejaculates, she retains significantly more sperm than she does after non-orgasmic sex. When she doesn’t orgasm, or she does so more than a minute before her male partner, little sperm is retained. I don’t know how common it is that a male will continue with the love-making for 45 minutes after he has ejaculated. Just saying.

Pair bonding

It is worth noting that we are not the only species to experience orgasm – female climax has also been documented in bonobos,chimpanzees and Japanese macaques. Anthropologist- primatologist Sarah Blaffer Hrdy draws on this information and suggests that “It is possible that as in baboons and chimps the pleasurable sensations of sexual climax once functioned to condition females to seek sustained clitoral stimulation by mating with successive partners, one right after the other, and that orgasms have since become secondarily enlisted by humans to serve other ends (such as enhancing pair-bonds).”  Hrdy suggests that the female orgasm may have evolved in our non-human ancestors in order to encourage females to have sex with multiple males as some sort of reward system or as an anti-infanticide strategy (if the male thinks any offspring may be his, he is less likely to kill them), but it may have evolved in humans to maintain monogamous pair bonds. After all, just because a trait may evolve for one reason does not mean it cannot then be employed for another. But there is little evidence to support this theory.

Heritable orgasms

This may not be something you necessarily want to think about ladies, but you can thank your mum (or not) for your ability to orgasm. A recent study examining the “orgasmability” of identical twins versus non-identical twins found that genes do indeed play a role in orgasm. On the face of it, this finding appears to be in line with the by-product hypothesis. HOWEVER. Contrary to the expectations of the by-product scenario, the researchers found that opposite-sex twins and siblings had virtually no correlation in orgasmability. So despite sharing the same amount of genetic material, it looks like the underlying genetics, and thus the underlying evolutionary pressures, appear to differ between the sexes. (Note: The methodology of this study is a bit dodgy, it is self-report and asks different questions to males and females, but the results are interesting nonetheless).

There you have it. Some thoughts on the female orgasm from an evolutionary perspective. What do you think? I think I need to change careers and investigate things like “upsuck” and “flowback” all in the name of SEXY SCIENCE.

Until better designed experiments take us closer to the answer, let us for now just appreciate the female orgasm for what it is. I wish you all happy orgasms this weekend.

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7 thoughts on “The female orgasm: An evolutionary adaptation, or a happy accident?

  1. Love this post, really enjoyed reading it. Thanks!

  2. David Marjanović says:

    *wave* Just wanted to say that I finally found your blog via Jadehawk’s twitter feed, after you fell off the Internet maybe two years ago. 🙂

    Also, I’ll link to this beautifully detailed post next time the topic comes up on Pharyngula (it regularly does).

  3. solongand says:

    Interesting read! I’ve often wondered myself if there is an evolutionary purpose. I suppose as humans we’d like to think that it’s for ‘pair bonding’ and having a man that can give you an orgasm is the sign that you’ve ‘hit the jackpot’ as it were. (Incidentally I think ‘hitting the jackpot’ sounds like another way of saying ‘spanking the monkey’, but I digress)

    But I imagine it may be just a happy coincidence. What often interests me the most when I’ve talked to other women about it is that there seems to be a great variance in what women require to actually reach orgasm. Some have never had one, not even when trying themselves, and others only need to have a bumpy (but very happy) bus ride.

    Also there’s the question of the different levels of orgasm. A lot of people focus on the clitoris but there’s also the infamous g-spot (which I think some scientists are still convinced is some myth that women made up)

    Anyway it’s all very fascinating, and certainly one of the perks of being a woman!

    PS: Out of curiosity I just typed ‘orgasm’ into the scholar.google.co.uk search and limited the search to anything before 1950. It’s entertained me for a while 🙂

  4. Anneliese says:

    If the sperm is significantly more retained, then why has the upsuck theory been discredited?

  5. Adam Darr says:

    I love it when I find chicks who have clueless significant others, who have no knowledge of how to pleasure women.. It’s great because I feel needed 😉

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