Learning from old science books: Part Two

Hello readers! In the last post, we dived into a Victorian science textbook: Charles Lyell’s Principles of Geology, from 1830. We explored the state of the geological sciences 200 years ago, and acquainted ourselves with the intellectual battle between the vulcanists and neptunists (which was a lot less science-fiction than it sounds, and fought with stratigraphic logs and pencil sketches). We pondered the difficulties of interpreting past processes from present-day rocks, and determined that “facts” are only the most logical solution to a problem currently available. In particular, we discussed Lyell’s views on climate, and how perceptions shifted when the theory of plate tectonics emerged.

This week, we’re dealing with fossils. Specifically, we’re going to dig into Lyell’s refusal to accept that life could evolve, and explore his paradoxical views on extinctions. We will see how stubbornness and bias can undermine scientific objectivity, and we will ask whether scientific research can ever be free from these shackles – especially when religion and reputation are involved.

But before we get ahead of ourselves, let’s set the scene. It’s 1830, and Principles of Geology has just been published. What did people know about fossils? And what did they know about the origin of species, before Darwin published On the Origin of Species (1859)?

The rocks don’t lie, but they can be misinterpreted

By the Victorian era, it was impossible for anyone to deny that life on Earth had changed throughout history. Thousands of fossils had been found and documented, creating a detailed record of new species arriving and old ones going extinct. Nobody could determine the timescales involved, but they knew that history was longer than the Bible suggested – and of course, this put strain on Christian beliefs. It was clear that each of these ancient species had thrived at different times, and that they hadn’t all arrived here on god’s first Friday. Trilobites, graptolites, ammonites and giant lizards came from a time before the Bible – and every one of these fossilised creatures was a testament to the inaccuracy of the Testaments.

Still, there were plenty of scientists who were happy to abandon the literal implications of the Bible while maintaining their Christian faith. By 1830, there was a widely-held view that life on Earth was becoming increasingly complex over time, and that there was a general “progression” towards greater intelligence. Scientists had noticed that fossils tended to be simpler lifeforms compared to animals today: they were mostly shells or plants, and sometimes the odd fish. Nobody was out there digging up fossilised giraffes – so people were starting to wonder whether life had been adapting over millions of years, shifting towards more complicated biological forms. However, these scientists couldn’t provide any feasible mechanism for their theory. It would be a few more decades before Darwin waded into the argument to put these ideas to rest.

Unfortunately for Lyell, the fact that life could change was a clear contradiction of his key idea: uniformitarianism. He believed that the present was the key to the past, and that the conditions at the Earth’s surface had always been broadly consistent. Using his method, rocks and fossils could be interpreted based on current, observable processes – and this theory worked well for sedimentary and volcanic deposits. For example, sandstones always have similar characteristics, no matter their age, and it makes sense that physical processes driven by wind or water will have always followed the same rules. However, Lyell’s key tenet of uniformitarianism was much harder to apply to the fossil record. All the evidence suggested that life on Earth was constantly changing in appearance and abundance – and Lyell saw this as the exact opposite of everything he had proposed.

Gospels, fossils, and unthinkable questions

Charles Lyell was a Christian. His book contains frequent references to a divine architect, and any attempts to interpret the fossil record are presented as a means to understand god’s plans, rather than as a means to undermine Biblical truths. Although Lyell was happy to disregard the absolute dates and ages presented in the Bible, he never questioned the existence of god. In fact, this is one of the key reasons that his book was so successful: he pushed the boundaries of Christianity, but he didn’t push them very far. The majority of Christians were comfortable with the aims of his work.

As we discussed in the previous post, the geology community in the early 19th century was split into two groups. The first group contained stubborn Christians, who were searching for geological evidence of the great flood. The second group contained stubborn atheists, who were arguing that the facts in the Bible were demonstrably false, and that the world had come into being of its own accord, long before humans had existed. By styling himself as both a Christian and a pragmatist, Lyell managed to bridge the gap between these groups. He presented his geological theories as simple, physical rules with no religious agenda, comparable to other sciences such as physics or chemistry. In fact, he likened geology to astronomy: just as astronomers had discovered the vastness of the universe, geologists had now discovered the vastness of Earth’s history.

Lyell’s reimagining of the geological sciences hinged on one, key idea: uniformitarianism. In his view, only present-day, observable processes could be sure to occur – so any inferences of great catastrophes in the ancient past were entirely baseless. He also believed that life on Earth should be governed by the same principle. According to him, all living creatures had been placed here by a divine architect, and they had all remained largely unchanged. This rigid conceptual framework guided his interpretation of the fossil record – and it meant that there were some questions that could never be asked. For example, Lyell never queried how humans came to be here. He stuck to his tenet of constancy: nobody had witnessed the birth of humanity, so there was no point trying to explain it, as no hypothesis could ever be proved.

Progression and evolution, according to Lyell:

The concept of progression bothered Lyell intensely, and he devoted multiple chapters to arguing against it. The idea that life could change gradually over time contravened his law of uniformitarianism – and rather than abandoning or modifying his idea, he insisted that the way of interpreting the fossil record should be changed.

One of Lyell’s most problematic assertions was that mammals had always existed. He insisted that they were an intrinsic part of life on Earth, even though it was well-established that there were virtually no mammals in the fossil record. The only large creatures preserved in rocks appeared to be lizards, fish or amphibians. Nobody had uncovered any fossilised hedgehogs, for instance. And they certainly hadn’t found any fossilised humans. How, then, could Lyell argue that mammals had always existed, without any evidence?

Lyell turned this question around. How could anyone argue that mammals hadn’t always existed, given that the fossil record was incomplete? He based his argument on the gaps in the evidence, rather than on the evidence itself. Most fossils, he pointed out, were clearly from the oceans, and not from land. He argued that because Europe had evidently been submerged for much of its history, no mammals could ever have lived there. The reason for the lack of mammal fossils was all thanks to geography: you can’t expect to find evidence of mammals if they never lived there. He suggested that while Europe was submerged, other regions of the Earth would have been uplifted – and that these ancient continents, no longer above the sea, would have housed all the mammals at that time.

The progression of life, in Lyell’s view, could also be disproved by the fluctuating complexity in the fossil record. By 1830, enough fossils had been documented and dated to show that Earth had witnessed periods of regression, where life became simpler and more sparse, rather than more complex. Even if someone dared to disagree with Lyell’s assertion that mammals had always existed, they would struggle to argue against the fossil record.

The fossil record from a modern perspective

Lyell’s standpoint is curious, to say the least. He wasn’t completely wrong, but he certainly wasn’t right, and his arguments were contradictory. For example, he was right to suggest that the fossil record is incomplete, because of course not every creature gets fossilised. Fossilisation requires a very specific combination of conditions: for a start, the body needs to remain solid enough to make a mark, and this favours bony, shelly creatures like ammonites more than soft, fleshy creatures like jellyfish. Even then, the body must be buried in one piece, without being torn apart by waves or other creatures. And once buried, the bones must be preserved somehow, and they must survive millions of years without being distorted or melted. Creatures are far more likely to be fossilised in the sea than on land, so Lyell was partially right: the fossil record is biassed towards ocean creatures. However, this is hardly convincing evidence for the eternal existence of land mammals.

To me, Lyell’s insistence on mammal persistence brings to mind a certain teapot in orbit. It is, as Bertrand Russell might have put it, an empirically unfalsifiable claim. If Lyell wanted to prove that mammals had existed since the dawn on time, he should have presented a mammal fossil from the dawn of time. Instead, he made an assertion, then argued that there was no way to disprove it.

Of course, this type of “logical” reasoning opens the door to all manner of fantastical possibilities. If Lyell could claim that life had remained largely unchanged for all of time, I could easily claim that in the Devonian period, the Earth had been riddled with hedgehogs. According to Lyell, there is no way to prove otherwise. There could have been billions of spiky critters scurrying around the prehistoric woodlands, and we would never know. So I’m going to keep believing in my Devonian hedgehogs, and you can’t stop me.

Also, had Lyell still been around today, I’d have liked to hear his opinions regarding whales. Because even if all the hedgehogs were hanging out on a continent that no longer exists, protecting themselves from being incorporated into the fossil record, I can’t help but wonder what all the whales were doing. Or all the other marine mammals, for that matter. I suppose they were probably swimming around in the sea – which does make you wonder why there aren’t any whale fossils. I mean, it’s not as if large animals can’t be fossilised: Mary Anning discovered a massive Ichthyosaur in 1819, over a decade before Lyell published his book. So, Charles – if mammals had always existed, where are the fossilised belugas? The fossilised orca teeth? Or the fossilised narwhal horns? Even hedgehogs could have made it to the middle of the ocean, Charles. They only had to run fast enough.

In the end, Lyell’s arguments were easy to dismantle. Darwin’s theory of natural selection soon explained the diversity of the fossil record, and the apparent regressions in the complexity and abundance of life were soon accepted to have been caused by mass extinction events. Fossils have now been collected around the world, and nobody has uncovered any evidence of Devonian hedgehogs, or of any mammal-like creatures before the late Carboniferous. That’s only 300 million years ago – and for reference, life has been around for about 3.5 billion years.

Life and extinction, according to Lyell:

While Lyell believed that the origin of life was due to the intervention of some divine creator, he viewed the extinction of species as an entirely natural process. He spent an entire chapter detailing the many ways in which humans had made thousands of species extinct around the world, and he even wrote about the recent, well-documented eradication of the Dodo. Extinction, in his view, was the natural way of the world, with no moral or religious implications. Even if god had created life, Lyell thought that it was perfectly reasonable for these lifeforms to compete and destroy each other.

The extinction chapters are unashamedly brutal, and heavily colonial. Lyell even devoted a paragraph to explaining how the native peoples of America and New Zealand would one day become extinct, having been out-competed (i.e., massacred, starved, infected) by European settlers. I’ll admit, I didn’t expect to find white supremacist ideals in an 1830 geology textbook – but in retrospect, that was a naïve assumption. I guess Charles Lyell would have argued that because racism exists in the present, it must have always existed in the past.

Aside from the violent and politically contentious drivers of extinction via competition, Lyell also presented several physical processes that might be responsible. All of them are associated with shifts in the distribution of land and resources: for example, the creation of new valleys might connect lands and seas that were originally separate, or lines of volcanoes might rise up to divide them. Lyell even described climate change as a driver for mass migrations, and acknowledged that species in hot or cold extremes would have nowhere to turn when temperatures shifted – a concept with which modern polar bears will be very familiar.

Overall, the chapters on extinction strike an uneasy balance between Christian views and solid evidence. There are also some baffling contradictions. For example, despite his constant insistence on uniformitarianism, Lyell was perfectly comfortable with the idea of mass extinction events, and even described them as being part of god’s plan. In one chapter, he described a “refrigeration” so severe that “scarcely any of the pre-existing races of animals would survive, and, unless it pleased the Author of Nature that the planet should be uninhabited, new species would be substituted in the room of the extinct.” Firstly, that’s one hell of a fridge. Secondly, this feels decidedly out of place, following his arguments for eternal mammals. If god can step in and alter Earth processes at any given moment, why would we assume uniformity since the dawn of time? You can’t argue for uniformitarianism while also arguing for divine intervention.

It is also interesting to see how Lyell justifies human brutality as being part of god’s plan. For all his talk of uniformitarianism, he never dared to explore the notion that humans were causing sudden and irreparable damage to the environment. He openly acknowledged that humans were responsible for wiping out the dodos, but he presented the information without pondering the implications. The dodos are dead – so what? You won’t catch those beaky landlubbers in the fossil record any time soon. And how might a new species rise up to take their place? Well, he left this as an exercise for the reader.

The only limit is your limited imagination

Interpreting evidence always takes a bit of imagination. Science is mostly problem solving, and we can only ever solve these problems with the tools that we have been given. It goes without saying that Charles Lyell had a different set of tools than the ones we use today – not just in terms of technology, but in terms of his internal analytical framework. His interpretations were guided by his Christian beliefs, some of which he treated as immutable facts, while others he viewed more as moral guidance, influencing his perception of the natural world.

Lyell’s assertion that mammals had always existed might seem crazy to a modern reader, but that’s because we learn about evolution from a young age. You probably can’t remember the first time that someone told you about humans being descended from apes, because it would have happened so early in your childhood. By the time you learnt about natural selection in school, you had probably picked up the basics already. The term “evolution” is used so frequently in popular culture that it has become an unshakeable fact, even to those who don’t understand its origins or significance.

Charles Lyell was raised within an entirely different framework. He had no in-built concept of evolution – just a hardwired certainty that the world had been deliberately crafted by a higher authority of unimaginable power and ambition. Although the fossil record in 1830 contained far fewer specimens than we have today, the main evidence was there – and yet the Victorian scientists came to starkly different conclusions. Their minds had been moulded by Christian teachings, and their imaginations had been limited in ways that they couldn’t perceive.

For me, Lyell’s chapters on fossils read as a cautionary tale on bias and mental conditioning. Lyell couldn’t admit that mammals were a recent phenomenon, because this would undermine his core tenet of uniformitarianism, as well as his deeply-held belief in a divine creator. The Bible states clearly, on numerous occasions, that men are superior to animals, and that humans are special – yet the fossil record suggests that we are just part of a long line of failed organisms. Lyell’s Christian upbringing made this prospect unthinkable, and so he cast it aside in favour of a theory that matched his understanding of the world.

The evolution of ideas

Principles was first published in 1830, but Lyell published many subsequent editions over the following decades. And in this time, there was a huge shift in our understanding of life on Earth.

At the time of the first edition, the evolutionary theories of Lamarck were starting to gain popularity around Europe. Lamarck’s idea (or at least, the one he popularised) was that animals would strengthen or lose characteristics in response to their environment, then pass these changes onto their children. Lyell disliked this idea intensely, and he argued increasingly strongly against evolution in every subsequent edition of Principles. In his private letters, which were published only recently, his disgust for the concept is expressed in even stronger terms; in fact, he appears quite obsessed with it. The notion that humans and apes could share an ancestor seriously rattled him – and I can only assume that this got worse over time, as the evidence piled up and he realised that he might have bet on the wrong horse.

When Charles Darwin published On the Origin of Species in 1859, he remarked on how influenced he had been by Principles of Geology. His theory of natural selection was controversial, and ruffled plenty of feathers, but the scientific tide was already starting to shift. In the tenth edition of Principles, in 1866, Charles Lyell finally softened his stance on evolution. He modified his fossil chapters, and conceded that it might (*might*) be possible for life to evolve over very long times.

Looking ahead

We can only ever interpret our surroundings based on laws that we believe to be true. This presents a fundamental obstacle to scientific advancement, because everyone nurtures a different set of laws. We can be informed by our observations, by our schooling, by our religious upbringing, or by our own ego – and this means that no interpretation can ever be free from bias. Present the same evidence to different people, from different parts of the world, different religions, or different times in history, and they might come to different conclusions. Truths are only determined by general consensus.

Although general consensus may be the best way to determine truth, it isn’t without its pitfalls. In this modern era of globalisation, our scientific biases are becoming more homogenised. Natural selection is now taught in schools around the world, and while I’m certainly not arguing that this is a bad thing, it means that we are all viewing the world through the same lens. So, what will happen to our scientific interpretations?

Every theory is born from gut instinct, and gut instinct is born from our life experiences. In a world where everyone learns the same maths, the same physics, and uses the same set of tools, interpretations will become more similar. Facts are only ever the most logical solution to a problem – but in order for any solution to be deemed the most logical, it must be singled out from a field of other, less viable solutions. So, if we narrow the scope of our interpretations by homogenising and enforcing our methodologies and beliefs, then our options for identifying truths will also be limited. Looking back to 1830, we can see that Lyell had been blinkered by his Christian upbringing, but he had no idea that this was the case. It makes you wonder how we might be blinkering ourselves in the modern age, limiting our scientific advancement.

In summary…

Objectivity is difficult. Bias is unavoidable. Science is a minefield. That being said, I hope you enjoyed this week’s post! The third and final instalment is on its way, and it’s all about igneous rocks and volcanoes. Hopefully these discussions on the nature of science don’t feel too out of place on a science fiction blog – although I should apologise to the people who came here for the medieval fantasy. Ordinary service will be resuming soon!

Happy reading, and have a lovely week!