“So daddy, where do babies come from?”
(cough) Well the stork delivers them!
Of course we laugh when we think about such questions…and answers. Everyone knows where babies come from and why. At some point in your life you learned e answer, getting the information from parents (I didn’t!), a “hygiene” class at school (I didn’t!) or a more knowledgeable friend (I did!). Usually such information from your friends was chock full of errors of imagination.
Reproduction seems so obvious to us now. Even if we don’t know the details, we know about the birds and bees. For humans and an overwhelming number of other species, both male and female contribute “stuff” that, together transforms itself into a baby. These days we take our understanding of the baby making process so much for granted that it’s amusing to look back at the intellectual struggles of early scientists as they tried tofigure it all out.
Besides, getting there is way more than half the fun anyway!
There was a great deal of the absurdity behind the discovery of the facts of life – how men in the 16th through 18th centuries groped, sometimes brilliantly, sometimes not, for answers to the burning questions about where babies come from. One part of the saga stands out above the rest because it involves sewing tiny taffeta pants for frogs.
Although the simple answer to the question ‘where do babies come from?’ is fairly obvious – they come out of the female vagina – arriving at an explanation of how the baby got there in the ﬁrst place proved quite diﬃcult.
“It seems very likely that early human populations did not know that intercourse led to babies. There are number of reasons for thinking this. Firstly, how could they know? The link between intercourse and pregnancy is not at all clear or immediate – people can easily have intercourse without the woman getting pregnant and the ﬁrst signs of pregnancy may not be seen for weeks after the act. This surprising supposition is supported by the widespread existence of matrilineal communities in hunter-gatherer societies, which suggests that men’s role in generation was uncertain.”
It has been argued that the male role was not revealed until the domestication of animals which only have intercourse during estrus. The role of the male (and thus the human man) in the reproduction then became obvious. No male, no mating, no calves.
Which raised the question -how did the baby get in there in the first plac?
Aristotle divided all animals into two kinds – the ‘bloodless’ animals (insects and so on), which generated spontaneously, and the remainder, in which mating played a decisive role. For Aristotle, the woman (or the female animal) provided the ‘matter’ for the baby, through her menstrual blood, while the male’s semen gave that ‘matter’ form, like a seal stamping hot wax. Another analogy, which echoes down to the present day, was that semen was like a seed (‘semen’ means ‘seed’), which was sowed on fertile ground.
And so it was for 1,500 years or so.
The idea pf preformation, or “preprogrammed encasement of successive generations,” reigned during the 16th century. Basically, preformation was appealing because it held that all humans are related, sharing a common ancestor. Scientifically, preformation was appealing because it seemed t explain the continuity between generations and the similarities between parent and offspring.
All egg-laying animals, but also all viviparous (live-born) ones like us, were assumed to come from an egg inside the female, which was the equivalent of a seed for plants. Inside that egg was a preformed body with another egg. Inside that egg was a preformed body and so on back in time, all the way back to Eve. The pull of the egg was strong and for the earliest supporters of preformation, it was easy to believe that every being – present and future-was made at the time of creation, with the first female containing all the future bodies of her descendants.
Kind of like those Russian dolls. The other problem of course is that no one had ever seen a woman’s egg.
Yet with all the emphasis on eggs and the female role in reproduction, clearly something about the male mattered too. And it was common for preformationists to believe that males contributed a “seminal liquor” -a sort of procreative potion.
Thanks to Antonie van Leeuwenhoek’s adventurous spirit and his microscope, history marks him as the first person to actually see “seminal worms” – as sperm was often called (with capital letters no less) in 1677.
Leeuwenhoek had been the first to see bacteria and microbes in water.
in autumn 1677, a young medical student from Leiden, Johann Ham, brought Leeuwenhoek some pus mixed with semen to examine. Ham claimed that this had been produced by a ‘friend’ who had ‘lain with an unclean woman’. When Ham had looked at the sample under his microscope, he had noticed many ‘animalcules’ in it; alarmed or enthused (it is not clear which),
Ham brought the sample to Leeuwenhoek, who conﬁrmed the observation and did the obvious thing: he looked at his own semen. To his amazement, Leeuwenhoek saw there were millions of tiny animalcules thrashing about in the sample. These things were eventually given the name by which they are still known today, and which completely misclassiﬁes them: ‘spermatozoa’ – semen animals.
Leeuwenhoek thought that the spermatozoa were merely another example of the ‘animalcules’ he could see everywhere he pointed his microscope. He was much more interested in a tangled mass of tiny vessels which he saw in ‘the denser substance of the semen’. This structure led Leeuwenhoek to claim without the slightest evidence that ‘it is exclusively the male semen that forms the fetus and that all the woman may contribute served only to receive the semen and feed it’.
Leeuwenhoek did not immediately grasp the signiﬁcance of his discovery of animalcules in semen.
This created a new revolutionary idea – some preformists now concluded that each of those seminal worms contained the preformed us thus beginning the debate between the “ovists” and the “spermists.” It was of course revolutionary considering babies came out of women and there could be no babies with sperm alone. Something was clearly going on in the oven.
For nearly 150 years, thinking about generation was dominated by either ‘ovist’ or ‘spermist’ views. Each approach considered that only one of the two parental components provided the stuﬀ of which new life was made, with the other component was either food (as the spermists saw the egg), or an immaterial force that merely ‘awoke’ the egg (as the ovists saw the spermatozoa).
Enter Lazzaro Spallanzani (1729 – 1977) and his frog experiments. Spallanzani (called Magnifico!) proved that life doesn’t arise spontaneously from “meat juices”, that there are microbes which can exist without air, found that saliva aids digestion and paved the way for the first narrowly focused scientific papers (as opposed to the book long “papers” which had existed previously).
Within the ovist-spermist debate of his time, he created the first frog contraception, by crafting little taffeta silk pants for his male subjects to test whether or not semen was essential for reproduction.
Spallanzani’s tiny frog pants allowed the animals to assume mating behaviors but blocked the exchange of fluids, whatever those fluids were believed to be. And what happened of course was that no frog babies were made. However, when he collected the semen hat the frogs had deposited in their pants and then artificially fertilized the frog eggs, voila, he ended up with new frogs. With this elegant and probably fun experiment, Spallanzani concluded that semen matters a great deal to baby making.
Naturally, once you’ve made frogs, you’re not going to stop there. So Spallanzani was the first to artificially inseminate a dog, demonstrating again with his success that semen matters to reproduction and strengthening the implication of this discovery for humans.
And then it gets funny.
After all the experiments and a life time of scientific thinking, Spallanzani came to the conclusion that the little worms swimming in liquid had nothing to do with fertilization. Everything he looked at under a low powered microscope had things swimming or crawling on it. Why should these worms be so important?.
The reason why late 17th-century thinkers did not realize what to us seems blindingly obvious–that both egg and sperm make equal contributions to the future oﬀspring – was that there was no compelling evidence to make them appreciate this.
It was not until the 19th century that the requisite combination of evidence and theory came together. The development of ‘cell theory’ gave an explanation for why egg and sperm were equivalent, despite their diﬀerences – they were both reproductive cells. The other factor was that realization that heredity had a biological content and that something was inherited, which was contained in egg and sperm, respectively.
Reproduction theory was ﬁnally given form in a monastery in Brno, where Gregor Mendel was just one of many people thinking about the nature of heredity. Oddly enough, by the time that the fusion of egg and sperm was observed for the ﬁrst time in the late 1870s, it was almost an anti-climax. People thought it was obvious.
Which in a way, it was, but getting to such a point had been anything but straightforward.
DNA was not discovered until my lifetime and it wasn’t until April 2003 that the International Human Genome project was completed.
But of course there are those who still think the earth is 5000 years old, flat and that climate change is just a hoax.