He suspected some female animals could have babies without males, and noticed some animals had no males or females, that is, no sexes at all. But Aristotle may have worked out this theory by observing animals in which it is extremely difficult to tell the males and females apart, just by eye. For instance, some vultures, where the males and females have identically coloured feathers so that the sexes appear exactly the same, as opposed, say, to peacocks and peahens, where the sex is very evident.
While living on Lesbos, Aristotle had made sure to include hyenas in his animal studies. His great interest in the animal had been piqued by the rumour that ‘every hyena is furnished with the organ both of the male and the female’ – that they were hermaphrodites. Today, the reason for the rumour is plain: the female hyena has a clitoris so grossly enlarged that it looks, to the casual observer, much like a penis, especially when the clitoris is fully erect, when it can protrude to seven inches. Spotted hyenas are, in fact, the only female mammals that urinate, mate, and give birth through the tip of a clitoris. (Keep in mind that the hyenas give birth to infants that weigh between 1 and 1.5 kilograms – and sometimes to two infants at once.) The female hyena lacks an external vagina; in place of the labia majora, the fleshy folds that normally flank the vagina, it has a fused sac of skin, something like a scrotum. If you were to look inside the female’s ‘penis’, however, you would find a urinary and genital system far more typical of any other female mammal.
Aristotle studied his hyenas carefully. His were not the spotted variety, but striped, as were found throughout the Mediterranean region of his day. And like their spotted cousins, male and female striped hyenas look remarkably similar. Both have manes that are erected when the animal is threatened – manes so large that Aristotle described them as running ‘all along the spine’. The females had the same enlarged, penis-like clitoris as the spotted hyena, and the males appeared to have a large opening near the anus, looking much like a vagina. When it came time to dissect the specimens of hyena that he had collected, Aristotle soon realized that the rumour that the animals were hermaphrodites was untrue. In addition to noting the differences between the clitoris in the female and the penis in the male, he identified the opening in the male’s anus as a sweat gland. By virtue of its position, this structure, he explained, could easily be confused with a vagina. Behind the opening, however, he did not observe any plumbing that might allow it to be used as a passage through which fertilization might happen.
It was an obvious case, in Aristotle’s view, of mistaken identity, the external appearances hiding the significant differences in what was going on inside the animals’ bodies. And so these dissections reinforced in him the belief that the male and the female must play very different roles in reproduction. Why else would they have such very different reproductive organs? The more important question was: what exactly was the difference between the male and the female role in reproduction?
One of the influential philosophies at the time was atomism, the idea that everything in the world is comprised of very small, indivisible, fundamental units – the intellectual birth of the atom. In terms of making babies, atomism was interpreted to mean that the male and female bodily fluids contained a miniature, perfectly formed version of the adult body of the respective sex, broken into parts, down to a pair of little arms and little legs, a compact torso, and a tiny head. When the male and female fluids mixed together during sex, these small parts simply assembled into a small body, which grew larger once it was sown in the fertile ground of a woman’s body – the foetus. Conveniently, atomism explained how a child could resemble both mother and father, which made the concept quite popular among classical thinkers.
Aristotle did not agree with this atomistic view of the world. This was not, after all, what he saw happening in his experiments with birds. He had observed that hens would mate with more than one rooster. Yet, ‘even when the hen is trodden by two males the offspring does not have two such parts, one from each male’ – the only logical reproductive outcome, if you held to atomism. If the male bird supplied a miniature body part to each female with which it had sex, ‘the offspring should have had a double portion’, Aristotle argued, ‘but it does not’. When it came to chickens and other birds, this meant the ‘male supplies nothing material’. Likewise, of course, a woman who conceives after having sex with two men does not normally have a two-headed, four-limbed baby as a result. She isn’t even very likely to have two babies, unless she happened to have twins. These were facts of life that Aristotle could also observe.
In On the Generation of Animals, Aristotle put forward an improvement in the reasoning for why there was a sexual division in reproduction, one that had nothing to do with the male and the female both providing the offspring’s parts. In his scientific opinion, there were always two sexes in a species, because the male contributes the form and
