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Posts Tagged ‘reproduction

22 – sex, reproduction, science, bonobos

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the act, depicted by Leonardo, along with his intriguing mirror writing

Thinking on dolphins again, I remember reading claims about sophisticated dolphin language, at a vocal range beyond human hearing, and I’ve also read scientific dismissals of such claims. I’m thinking again about these questions (the communications of some birds also comes to mind) because the communicative complexity of language would have enabled human apes to, among other things, be species-aware of the connection between sex and reproduction – though unfortunately failures in that communication still result in unwanted teenage pregnancies. 

But I don’t seriously imagine that any other species – on this planet at least – knows that the joys of rump-pumpy lead to the much-later popping out of wee human replicants. For one thing, Matthew Cobb’s book The egg & sperm race provides an account of how confused we humans were, even at the time of Leonardo, about ‘the exact relationship between male, female and offspring’. They were particularly confused with regard to non-human generation. Ideas about barnacle geese being hatched from barnacles, mice being generated from wheat and vipers from dust were entertained at the highest level, even at the Royal Society in the 17th century. The spontaneous generation of the tiniest creatures was essentially a given for millennia. But human generation was also much of a mystery until relatively recently. Here’s a little summary from Cobb:

Although the real situation now appears obvious, discovering exactly what goes on was a long, complicated process. Even what might seem to be the most obvious step in generation – the link between sexual intercourse and pregnancy in humans – is really quite difficult to demonstrate. Part of the problem is that the clear signs of pregnancy do not immediately follow the sexual act. Even menstruation does not necessarily appear to be directly linked to pregnancy: although women stop menstruating when they are pregnant, some women always have irregular periods, while teenage girls can get pregnant without ever having menstruated. The link between sex and generation is so unobvious that in the 20th-century the Trobriand Islanders in the Pacific Ocean were said to be very surprised to learn that there is a connection between the two. All around the world, folktales of conception taking place in the most astonishing ways, such as by eating fruit (mango, lemon, apple, orange, peach ..), accidentally swallowing crane dung, or, more politically, being touched by the rays of a dragon.

The late 17th century, however, was the period in Europe when most of this confusion was cleared up, at least in the so-called developed world, thanks mainly to the work of four gifteded individuals, Francesco Redi (1626-97), Jan Swammerdam (1637-80), Nicolas Steno (1638-86) and Reinier de Graaf (1641-1673). Much of this work took place in the Netherlands, a major progressive and scientific nation in this period, backed by massive profits from the spice and slave trades. Of course another power of the period was England, and one of the most important figures in researching ‘generation’, as the problem of sorting out the reproductive process was then called, was William Harvey, famous mostly for working out the role of the heart in circulating the blood. Harvey was a pioneering experimentalist, and his approach to the issues was essentially correct, and quite revolutionary, but he lacked the necessary to work out the detail of generation. In particular, he lacked a microscope. His late work, de generatione animalium (1651), though mostly a restatement of Aristotelian doctrine, was inspirational in that he emphasised, through experiment, the importance of the egg in generation, regardless of species. Without a microscope, however, this claim couldn’t be fully verified. Microscopes, or magnifiers of various kinds, had been used since antiquity, but their full development came only after the invention of the telescope. Galileo built his own compound microscope in the 1620s but they remained largely a novelty until later in the 17th century, with the founding of scientific societies and academies, and the sharing of scientific experiments and tools. 

The four above-mentioned intellectuals (the word scientist didn’t gain currency until the nineteenth century) – one Italian and three Dutch – were friends, colleagues, and sometimes frenemies at a time when being first with scientific breakthroughs was even more important than during the covid19 era. There were no professional researchers of course, so you had to publish to get recognition and encourage patronage (and you often needed patronage to get published).

Francesco Redi, who combined a more rigorous experimentalism than was common at the time with the wit and urbanity that made him a mainstay at the court of Grand Duke Ferdinando II of Tuscany, to whom he acted as physician among other things, carried out careful research on insects which proved that they weren’t generated spontaneously in rotting foodstuff or anything else. His interest in the subject was inspired by Steno who had come to Tuscany from his studies in Leiden, via Paris, with a reputation as an expert in dissection and cutting-edge experimentation. Steno was in turn influenced by the greater mathematical rigour of the intellectuals at Ferdinando’s court. The two worked together on fossils and geology as well as animal anatomy. Steno was interested in the difference between viviparous and oviparous reproduction – that’s to say, between creatures who produce live young and those who lay eggs – and stumbled on a new, decisive insight, that female ‘testicles’, at the time believed to be internalised versions of male testicles, were in fact ovaries, a housing for the female’s eggs. This was an insight from observation, rather than experiment, but it was of course correct, and revolutionary.

Steno, Swammerdam and de Graaf had all met in Leiden where they engaged in their first adult studies (Leiden University in the mid 17th century had more student enrolments than Cambridge and was one of the most progressive learning institutes in Europe), and Steno and Swammerdam, being in the same year, became firm friends and collaborators there. After their Leiden studies, all three went to to France, a common destination for young Dutch intellectuals. Swammerdam and Steno were attracted there by an extraordinary French polymath, Melchisédech Thévenot, who had visited Leiden during their studies there, and who was head of a private academy in Paris, which eventually morphed into the Académie Royale des Sciences. 

But I’m getting bogged down in fascinating detail. Read Cobb’s The egg & sperm race for the story of how these individuals, and others, sorted out the story of ovaries, testes, semen and the equal contribution of males and females to offspring production. It’s a story of collaboration, rivalry and the struggle for both knowledge and recognition that captures much of scientific activity, then and now. 

The point of all this is to recognise how difficult it was for even the most complex species on the planet to work out the relationship between the pleasures of sex and the rather more mixed experience of childbirth – deadly for many, including my own grandmother. 

And yet, bonobos do it for pleasure and relief, openly, and manage to avoid having endless pregnancies, unlike  Anne Stuart, queen of Great Britain (18 pregnancies, none surviving to adulthood) and Maria Theresia, empress of Austria, and many other regions (16 pregnancies, only 3 of whom died in infancy), not to mention a horde of less ’eminent’ catholic martyrs to the world’s peopling. Bonobos have between five and seven infants, on average, in a lifetime, which is certainly more than enough. I’m not sure of the survival rate of offspring, but it would probably be higher if not for human depradations. 

References

Matthew Cobb, The egg & sperm race 

https://en.wikipedia.org/wiki/Melchisédech_Thévenot

https://www.britannica.com/animal/bonobo

Written by stewart henderson

January 18, 2021 at 7:18 pm