The human clitoris. Bigger than commonly supposed

It’s a mystery worthy of Miss Marple herself. The clitoris vanishes every few generations and then needs to be rediscovered. Sometimes, this rescue from obscurity is to considerable fanfare. Why does this keep happening?

First, don’t panic. A vital anatomical structure is not really vanishing--it just disappears from anatomical textbooks every so often. Second—don’t just take my word for it--test this for yourself. Go into any decent bookshop and check out the medical anatomy section. Look up “clitoris” in the pictorial index. I guarantee that roughly half of the medical textbooks—ones that are used to train doctors--will disagree with the other half. One half will label, as if complete, a structure they will call the clitoris that is actually a wholly external organ. This is in fact the clitoral glans--a highly sensitive part of the clitoris—but definitely not the whole thing. The remaining textbooks will detail a far more complex structure, about four inches in length, mostly internal, and with a variety of nerve pathways, complex mapping onto the sensory cortex of the brain, and a host of integrated organelles. Are half the female population notably different from the other half? No, they are not.

I have heard it said that the clitoris was invented in the 1960s, but this is just a joke playing on the sexual ignorance of a sexually repressed previous generation. In the sixteenth century Fallopia described clitoral structure--while Galen denied it existed. In modern medicine the complex, and largely internal, structure of the clitoris was documented (1) in 1851. Moving forward a hundred years, clitoral complexity was re-described in 1949 - showing a large organ that wrapped around a (potentially) inserted penis (2). However, many textbooks have been slow to catch up with research. In the early part of this century Helen O’Connell’s team (3) produced beautifully rendered MRI scans showing the size and complexity of the clitoris in three dimensions, now examinable in state of actual arousal (figure 1).

Every time this happens there is much excitement—and sometimes opposition. I have regularly given talks to interested folk—some of whom are biologists—who tell me that this is the first that they have heard of clitoral size and complexity. On a roughly monthly cycle I return a proposed paper on a peer-reviewed journal--where I am one of the reviewing peers—for making this omission, and direct the authors to relevant texts.

The eminent physiologist Roy Levin once told me that the clitoris was an “Iceberg organ, 7/8th s of it is always hidden”. Levin is one of the world’s leading scholars on this topic (4). Any work that does not reference him here has been very poorly researched. Why then is the size and complexity of the clitoris not more widely known? I think I know part of the reason.

Flowers at Midnight

Men want a magic button that will make their partners satisfied — i.e. orgasm during sex--and when this doesn’t happen there is a tendency to regard the female as somehow broken or inferior. Sigmund Freud was responsible for some of this mischief with his notion that clitoral (glans) orgasms were somehow immature. Sometimes, this view of females as imperfect copies of males in sexual terms can extend to a general theory about female sexuality.

This is because what works for men does not work for women, at least not every time. It’s as if I found some flowers at midnight and concluded that they must be faulty because the petals were closed. This 'flowers at midnight' view finds its fullest expression in the by - product theory of female orgasm.

The appearance of complex design in nature is explained by adaptation — the gradual fitting to the environment of traits that increase reproductive success. Some complex structures are the result of direct Darwinian selection. Some others exist because they piggy back on other adaptations. These structures have no functions in their own right, they make no contribution to fitness. The by-product theory of female orgasm argues that female orgasm exists only as a by-product of male orgasm and an analogy is drawn here with male nipples.

It’s a well-known factoid that we all start as female embryos and structures that will eventually grow into breasts remain vestigial in males. The by-product just-so story then proceeds to argue that because males (allegedly) needed sensitive penises to reward sexual behaviour, females then got a free ride (as it were) with an enjoyable but functionless clitoris. The late palaeontologist Steven Jay Gould (5) and his protégé Lloyd (6) championed the idea, first proposed by Symons (7), that female orgasm stands in relation to male orgasm as male nipples do to female ones.

But this analogy stinks. A nipple is a structure, whereas an orgasm is an event. Often, quite a dramatic event. The great biologist Bob Trivers once quipped that “One has to wonder how often Steve [Gould] has witnessed this blessed event to regard it as by-product”. That comment may be a tad unkind. However, a relevant point was raised. Male nipples are small functionless structures and the by-product account invites us to think of clitorises as smaller non-functional penises. But this is wrong on several counts.

"No man should marry until he has studied anatomy and dissected at least one woman." Honore de Balzac.

First, the clitoris is not a tiny vestigial penis — it is larger than an (unerect) penis and, as I have emphasised, it is also a complex organ with at least eighteen distinct interacting functional parts including muscular, erectile, and sensitive tissues. The nerves in question map to their own specific regions in the female brain’s somatosensory cortex — which is not at all like those of male brains (8). Nothing like this can be said of male nipples. Second, clitorises do things. They are the seat of female orgasm. The difference can be put this way; men never demand nipples.

Are orgasms important things? The by-product account says no, these things are not biologically important. In fact, by-product advocates claim that women are lucky to ever get orgasms at all (6, 7). Frustrated women are set aside - according to the by-product account the clitoris did not evolve under its own selection pressure and can therefore not be expected to work properly.

But perhaps these scholars are mistaken. Perhaps the clitoris is not a broken or imitation penis, but instead is a highly sensitive, beautifully designed, measuring instrument. Knowledge of its true complex structure prompts this view, especially its nature when aroused - as depicted in three - dimensional sonography in 2009 by Buisson and Foldés (9 and figure 1).

At this point an advocate of the by-product account is likely to bring up the fact that penetrative intercourse, without additional stimulation, is inefficient in generating orgasm in females. Well, this argument does not bear close examination either. As Carol Wade is reported to have said, “Sex is not a soccer game — the use of hands is permitted” (10). It might be noted in passing that the use of hands during sex to please partners is common in our primate relatives as well (11).

If the female sexual system is choosy about when, where and how orgasm occurs then we need to pay attention to that choosiness (12). It might tell us important things about our biology, as well as helping individuals to be happier in their sex lives. It is also vital to have good scientific knowledge to help combat the confusion and pain associated with female genital mutilation in its many forms — and to help us understand some of the reasons prompting these mutilations.

One thing that science seems to tell us is that females evolved under their own selection pressures and are not simply inadequate versions of males.

Even if we have cleared up the event/structure confusion—does that prove that female orgasms do something and if so, what? No, not yet. This is where things become a lot less certain and is a topic deserving of separate treatment.


1) Kobelt, G. L. (1851). De l'appareil du sens génital des deux sexes dans l'espèce humaine et dans quelques mammifères, au point de vue anatomique et physiologique, traduit de l’allemand par Kaula H, Berger-Levrault et fils, Strasbourg et Paris (1851) (1re éd. allemande: 1844).

2) Dickinson, R. L. (1949). Human sex anatomy: A topographical hand atlas.

3) O'Connell, H. E., Sanjeevan, K. V., & Hutson, J. M. (2005). Anatomy of the clitoris. The Journal of urology, 174(4), 1189-1195.

4) Levin, R. J. (2004). An orgasm is… who defines what an orgasm is?. Sexual and Relationship therapy, 19(1), 101-107.

5) Gould, S. J. (1991). Male nipples and clitoral ripples. Bully for brontosaurus, 124-38

6) Lloyd, E. A. (2005). The case of the female orgasm: Bias in the science of evolution. Harvard University Press.

7) Symons, D. (1979). The evolution of human sexuality.

8) Di Noto, P. M., Newman, L., Wall, S., & Einstein, G. (2013). The Hermunculus: What Is Known about the Representation of the Female Body in the Brain? Cerebral Cortex, 23(5), 1005-1013.

9) Foldes, P., & Buisson, O. (2009). REVIEWS: The Clitoral Complex: A Dynamic Sonographic Study. The journal of sexual medicine, 6 (5), 1223-1231.

10) Tavris, C. (1993). The mismeasure of woman. Feminism & Psychology, 3(2), 149-168.

11) Dixon, A. F. (2012). Primate Sexuality: Comparative studies of the Prosimians, Monkeys, Apes and Human Beings. 2nd Edition.

12) King, R., & Belsky, J. (2012). A typological approach to testing the evolutionary functions of human female orgasm. Archives of sexual behavior, 41(5), 1145-1160.

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