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Speaker spotlight - Dr Susannah Gibson

Dr Susannah Gibson, author of Animal, Vegetable, Mineral? introduces early experiments used to solve the mysteries of life and the fantastical creatures behind them, somersaulting polyps, suspicious sea sponges and frogs in trousers!

Susannah will be speaking at this year’s Festival during her event Animal, vegetable, mineral.

CSF: What made you want to write your book Animal, Vegetable, Mineral?

SG: The book grew out of some research I did for my PhD thesis. I realised that all the weird, and utterly engrossing, creatures I’d spent years reading about might make an interesting topic for a non-academic book. I think history of science makes for really engrossing reading: it’s got everything – quirky characters, dramatic experiments, big debates – all set against the backdrop of fascinating historical periods (the Enlightenment, in this case). Lots of the questions that were controversial then are still being debated today. So even though the experiments I study are more than 250 years old, the things they were designed to investigate (for example, how reproduction works) are still relevant to today’s society. 

CSF: What’s it about?

SG: It’s about how people have tried to understand, scientifically, the nature and meaning of life throughout history. Much of the book is set in the 18th century when people were obsessed with the idea of classifying all of nature into groups like ‘animal’, ‘vegetable’, and ‘mineral’. In this period, European empires were expanding and thousands of new creatures became known to western science. As naturalists studied more and more species from different parts of the world, they soon realised that lots of creatures don’t fit into these simple categories. To learn more, they conducted further experiments on things like corals, sponges, pond slime and the Venus fly-trap, and found that their results could lead people to question the existence of the soul, the role of God in creation, the existence of a ‘natural order’ and even the social order. It’s about how (seemingly) small questions can lead to very dramatic answers.

CSF: There are probably many weird and wonderful experiments scientists historically conducted. Which was the weirdest you came across? And which was the most controversial?

SG: One of the weirder experiments I came across involved an Italian clergyman named Lazzaro Spallanzani making tiny pairs of trousers for frogs as a way to investigate the theory of spontaneous generation. This was a theory that went back at least as far as Aristotle, and which was still widely believed in the mid-18th century. I don’t want to say too much now as I’ll talk more about this in my event on 18 March.

As well as experimenting on frogs (which are a perfectly good experimental subject, but not exactly novel), naturalists were extremely excited about experimenting on all of the new creatures being discovered around the world at this time. The Venus fly-trap was first seen by Europeans in the 1760s, and naturalists had a wonderful time trying to grow them in European gardens, and feeding them flies to figure out how they worked.

Some of the most controversial findings in this period came from quite straightforward experiments; for example, in the 1730s and ‘40s Abraham Trembley cut some fresh-water polyps in half (these are small green creatures that live in stagnant ponds) and watched as each part re-grew into a complete and fully-functioning individual. Cutting slimy little pond-dwellers in two doesn’t sound like a big deal, but Trembley’s results were startling: they seemed to prove that these creatures were half-plant and half-animal.

As well as destroying the idea of clear boundaries between the kingdoms, Trembley’s results made people speculate on bigger questions, such as: if you cut an individual in two, and each part regenerates, what happens to the soul? Have you cut the soul in two? Does this show that the soul is simply a function of matter? This experiment really made people think about how scientific results could affect, for example, religious beliefs.

CSF: What did these experiments prove, if anything?

SG: Lazzaro Spallanzani’s experiments on frogs in trousers proved that both the male and female parent contribute to conception; before this, the role of the male’s semen was debated, and many believed that only the female was essential to conception. The results of this series of experiments ruled out many of the prevailing theories of reproduction of the 18th century, including pre-formation theory. This theory stated that all the people, animals and plants that would ever exist had been created by God at the beginning of the world, then folded up in serial order and nested within its parent. These experiments also ruled out the possibility of spontaneous generation.

The experiments on Venus fly-traps and fresh-water polyps proved that the neat separation of all living things into just two categories, animal and vegetable, wasn’t always possible. These experiments and observations made people question the simple classifications that had been used for millennia, and raised the possibility of a new kingdom which was a hybrid between the plant and animal kingdoms. Today, scientists recognise dozens of different kingdoms, with the plant and animal kingdoms making up only a small percentage of life on Earth. These experiments also made people think about the similarities between living things, and it was in this period (a century before Charles Darwin published On the Origin of Species) that people began to speculate on the possibility of species transmuting into new species. 

CSF: How did it all affect or change society as a whole?

SG: These weren’t just scientific questions; they also had implications for theology, philosophy, politics and society at large. The Book of Genesis had described the creation of the earth and its plants and animals, and so most natural history followed the three-kingdom model (animal, vegetable, mineral). By suggesting that there were more than three kingdoms, naturalists were beginning to question the literal truth of the Bible. Fossils were particularly difficult to classify: they appeared to be made of stone, but looked like animals or plants. By speculating on their origins, naturalists found themselves doubting the account of the Creation given in Genesis. Of course, questioning the truth of biblical creation could lead to questions about, for example, the God-given power of monarchs, or the idea that society had been divinely ordered into upper and lower classes.

The 18th century was a period of Enlightenment; free thinking was encouraged, and interest in science was expanding rapidly. These kinds of questions fascinated Enlightenment thinkers; they were excited about the possibilities of using new ideas from science to question long-standing beliefs about the natural world, and the societies in which they lived.

CSF: So, what do you hope people take away from the book or talk?

SG: I hope that people will see that the questions we ask today about the meaning of ‘life’ are very similar to the questions asked throughout history (from at least the time of Aristotle), and that this questioning is a fundamental human activity. History of science is wonderful for letting us see science as a very human thing; it allows us to think about the bigger concerns that have always interested people. It acts as a mirror in which we see a part of ourselves that can sometimes be obscured by excessive detail: instead of asking, ‘what’s the result of this experiment?’ we ask, ‘why do humans experiment at all?’

I also hope that people will see how simple questions can become very complex very quickly; that curiosity is as important as knowing the ‘right’ answer. And that nature has created some truly extraordinary creatures.

CSF: What do you think your next book will be about?

SG: It’s in the early stages, so I don’t want to say too much yet, but there may be ectoplasm...