Like a Virgin by Prasad, Aarathi (recommended reading txt) 📕

To Leeuwenhoek, eggs existed so that the preformed embryos in sperm could be implanted in them. His stubbornness is all the more surprising when you consider that in addition to the discovery of sperm, the Dutchman is credited with the discovery of parthenogenesis, the development of the egg into a new individual being without fertilization by sperm. If you weren’t too sure that eggs existed, as Leeuwenhoek said he wasn’t, you might say that this process amounts to a female bearing offspring with no lasting input from a male – the equivalent of a virgin birth. And Leeuwenhoek was the first scientist to notice that female aphids had virgin births all the time.

An avid gardener, in the summer of 1695 he became somewhat concerned that the leaves of his gooseberry, cherry, and peach trees were damaged. At first he thought the mutilations were the work of ravenous ants, but on closer inspection, he spied aphids. Leeuwenhoek did with the aphids what he did best: he pulled out a microscope and, as had become his custom, he searched for the eggs of this new species. He found none. He then dissected what he guessed were the females. He found no eggs in them either. But he did find miniature, preformed aphids. The first specimen he dissected contained four young, and he removed as many as sixty from another.

This should have put an end to the idea that male semen, or sperm, was the sole instigator of new life. But there again, Leeuwenhoek had chanced upon an organism in which reproduction is by no means straightforward. The sexual tactics employed by female aphids are tricky and complex. Two hundred million years ago, the insects evolved a reproductive strategy that allows them to practise reproduction by parthenogenesis – in cycles. This means that female aphids do have eggs, and both the fertilized and unfertilized eggs of a female are capable of forming embryos. The small aphids that Leeuwenhoek observed when he cut open his female – those born live as a result of parthenogenesis – were exclusively female. What is more, a single female generated by parthenogenesis may contain three generations within her body: the numerous embryos of her unborn daughters and, within them, her granddaughters-to-be in the early stages of development. For aphids this amounts to a brilliant strategy for rapidly producing an immense population; a virgin female can, in theory, produce billions of offspring in a lifespan of roughly one month. Here was a stack of Russian dolls, miniature yet fully formed creatures in ever smaller packages, just waiting to be born – a perfect preformed embryo, but from a female.

Despite this finding, and von Baer’s production of the elusive mammalian egg from a dog, the egg continued to be considered the lesser element of reproduction into the Victorian age. In 1849, Richard Owen, who had classified spermatozoa as parasites, delivered a talk at the Royal College of Surgeons entitled ‘On Parthenogenesis, or The Successive Production of Procreating Individuals from a Single Ovum (Egg)’. Owen had coined the word ‘parthenogenesis’, yet he could not extricate from his mind the influence of sperm over the process. Instead of the potential of eggs to self-reproduce, his lecture expounded on the virtue of sperm. For him, a ‘virgin birth’ could only ever follow an original fertilization event – and fertilization required sperm. What he called ‘spermatic virtue’ was a power contained in sperm that could be divided equally among countless offspring. He told his audience that the development of an embryo by parthenogenesis differed from a normal fertilization involving sperm ‘only in... non-essential particulars’, by which he meant that the power of sperm was the absolute requirement.

In the late nineteenth century, Owen would come under fire for this explanation. His critics were formidable – among them Darwin and Darwin’s ‘bulldog’ supporter, Thomas Henry Huxley. Huxley was professor of general natural history at London’s Imperial College and had contributed substantial knowledge to the growing field of comparative anatomy and palaeontology. He levelled great criticism at Owen’s science and methods; in return, Owen published cloaked insults about Huxley’s own work. It’s fair to say that their earlier friendship had dissolved by this time. A colleague of Huxley’s even advised him to shoot Owen in a duel. The two scientists had running arguments on anatomy, aphids, and parthenogenesis. Huxley particularly attacked Owen’s references to a non-descript spermatic virtue or ‘force’ that could be retained through generations of aphid females, calling such speculations ‘ignorance writ large’. For his part, Darwin egged on Huxley to challenge Owen on this point.

Meanwhile, in Germany another distinguished professor of comparative anatomy, Karl Ernst von Siebold, also ridiculed the belief in all-powerful sperm. Siebold did not respond by producing more speculation, but by performing exhaustive experiments to investigate ‘true parthenogenesis’. This was, in contrast to Owen’s definition, the development of an egg that was perfectly capable of being fertilized by sperm but which had not been. For his test subjects, Siebold turned to aphids, bees, and moths. He knew the conviction that eggs must be exposed to spermatozoa before they can develop was very deeply rooted; he himself had once been a strong opponent of the existence of parthenogenesis.

In 1857, after years of study, Siebold published his findings on bees and Psyche and Solenobia moths; in a nod to Richard Owen, he entitled his text On a True Parthenogenesis. In his exacting observations, Siebold had noted that the unfertilized eggs of his moths produced female offspring, but that queen bees produced male drones through parthenogenesis and female offspring from eggs fertilized by sperm. Contrary to Owen’s definition, it was clear that new organisms could develop solely from eggs. Siebold also uncovered that not only can eggs develop into fully formed animals quite without any fertilization event but also that parthenogenesis