It seems remarkable to me that well into the twenty-first century we still have so much to learn about many parts of the human body.
Organs we’re all very familiar with - ones we take for granted - still have the power to surprise, in terms of new discoveries about their structure, function or evolution.
Top of the list of the most misunderstood of organs must surely be the clitoris? A structure whose function seems to be entirely about providing sexual pleasure to its bearer.
Incredibly, the structure of the clitoris was hotly debated by anatomists until just a decade ago when it was found that the organ was a lot more complicated than had been thought.
The text books had to be thrown out the window because this organ - really an anatomical constellation - actually comprises the opening to the vagina and the front part of the urethra, as well as the organ formally known as the ‘clitoris’.
French researchers have recently made a 3D printed model of the clitoris that’s going to be used in schools to help educate children about sex. This has prompted some in the media to proclaim that it heralds the start of a new sexual revolution.
The 3D print of the clitoris is a thing of beauty. At first glance, it reminded me of a ‘my little pony’ toy my daughter once owned.
As I looked for longer I saw a bright pink stick insect, then a penguin, and the reproductive organs of a beautiful orchid.
The model shows us just how complicated the clitoris really is, and how it’s woefully misleading to describe it as simply the female equivalent of a penis. It’s not.
Now, if we take a perspective centred entirely within the human experience, it may be right that the clitoris functions only to provide sexual pleasure. After all, research shows that stimulation of the clitoris is the main way women achieve orgasm.
But the complexity of it’s structure shows us that there must be a lot more to this organ than meets the eye. Is it an organ of pleasure for other animals as well?
It might come as a surprise to learn that not only is the clitoris found across the mammals, it’s also found in birds. Just within our own group of mammals - the primates - its size, shape and function vary enormously.
Compared to our cousins, it’s externally rather small, the head (glans) sitting within the lips (labia), and all of it hidden beneath a hood, until it is aroused.
Still, I suspect the human clitoris is a lot more sensitive to stimulation, especially given that we’ve still no idea if any other mammal enjoys female orgasm.
Now, contrast this with the spider (or squirrel) monkey of South America. Their clitoris dangles between the legs - all five centimetres of it - being longer even than the penis.
Why is the spider monkey clitoris so long? Well, it plays a social role in the species, which has a rather peculiar way of organising itself socially compared to other primates.
Spider and squirrel monkey societies are sex-segregated: males travel and interact in all-male groups, while females reject males and travel alone or only with their offspring.
Scientists have even observed that dominant females will display their clitoris in a manner similar to the way males expose their penis, as a sign of dominance over other group members.
What about our closest cousins the gorillas and chimpanzees? Is their clitoris just like ours?
Gorilla clitorises are also quite long, but don’t extend much beyond the labia. They’re enclosed in a foreskin, and are long and hollowed out, not barrel shaped like ours.
Just why is the gorilla clitoris hollow? Um, well, one suggestion is that it makes it easier to scent mark territory using urine (think drip, drip, drip…)
What about our closest cousins the chimpanzees? In common chimps and bonobos the clitoris is also a cylinder, and hidden beneath a hood, just like ours. But, it’s a lot larger than a human’s.
Even more remarkable, the bonobo clitoris sits in a different spot to both common chimpanzees and humans: it’s found between the legs, not towards the front of the body, which aids sexual stimulation.
Bonobos have a rich and varied sex life that’s strikingly different to common chimpanzees, and in many ways, strikingly like our own.
They engage in face-to-face copulation - the ‘missionary position’ - undertake manual and oral stimulation, and even kiss on the lips. Sexual activity happens between the sexes and within the sexes.
A clitoris placed between the legs ensures it’s stimulated when in missionary mode.
Sex is used by bonobos to get food, to form political alliances, to shift positions in the power hierarchy, and seemingly, just for fun.
The human clitoris continues to be an object of beauty, pleasure, of mystery and intrigue; and sadly, sometimes of derision and exploitation.
But’s surely it’s function is no secret? It’s used across the primates to procreate, subjugate, and even to entertain.
I can’t understand why we don’t celebrate the important role the clitoris plays in our lives. I’d like to see a massive sculpture of the new 3D printed organ erected inside every science museum in the world!
Authors: Darren Curnoe, Director of the Palaeontology, Geobiology and Earth Archives Research Centre (PANGEA), UNSW Australia