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Decades before Darwin, there was a debate about transformism, the idea that species change over time.
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Two colleagues from the French natural history museum faced each other.
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They hoped to settle the debate by unpacking ancient mummies and comparing them to modern mummies.
Throughout the early 19th century, the question of whether animals could transform into new species was hotly debated in scientific circles.
In 1798, Napoleon Bonaparte brought with him a whole host of savants – geologists, engineers and other scientists – about his failed attempt to take over Egypt. A collection of mummified animals that the scientists brought back from Egypt seemed to hold the key to the question of species transformation.
Naturalists Georges Cuvier and Jean-Baptiste Lamarck, colleagues at the French Museum of Natural History, represented the two sides of the debate.
Cuvier mocked Lamarck in his obituary
In 1832, a spot eulogy was read at the French Academy of Sciences. The honoree, Lamarck, and the obituary writer, Cuvier, were both dead.
In acknowledging the death of a colleague who had written to Cuvier, one should both praise their “useful works” and at the same time draw attention to “more questionable” ideas that emerged from a “vivid imagination.”
In this case, Cuvier was bashing Lamarck’s theory of transformism. Lamarck thought that the simplest animals became more complex over a long period of time, turning into entirely new species. This was nonsense to Cuvier, who thought species could never change.
Naturalists Cuvier and Lamarck had first argued thirty years earlier when a mummified ibis arrived at the museum.
The ancient bird was indistinguishable from a modern bird, which seemed to prove Cuvier was right.
What is transformism?
In his elegy, Cuvier mocked Lamarck’s suggestion that a “desire” to swim causes webbed feet in a water bird or elongates the legs of another species that prefers not to get wet.
This was almost 60 years before Charles Darwin published his theory of natural selection. At the time, some of the biggest questions in natural history were why animals went extinct and new ones appeared after large gaps in the fossil record.
Lamarck is probably best known for writing that giraffes got their long necks by reaching for leaves and passing that trait on to their offspring. It wasn’t a completely new idea, but Lamarck was unique when he said that such behavior could gradually lead to a new species.
He wrote that species are an easy way for people to catalog living things. Because animals were constantly changing, a species was only a temporary category.
Cuvier, one of the founders of comparative anatomy, took a different view. Species were permanent. But he could not deny that at certain times new species of animals that never existed before appeared in the fossil record.
Every now and then a natural disaster led to a new ‘era’, Cuvier thought. Some species became extinct; others appeared suddenly. If Lamarck were right, Cuvier said, there would be all kinds of intermediate fossils, halfway between one species. and another.
Geoffroy finds mummies in Egypt
Mummified animals thousands of years old seemed a perfect starting point to look for evidence of change between ancient animals and their descendants.
Among Napoleon’s scholars was Etienne Geoffroy Saint-Hilairea naturalist who has discovered every mongoose, fox, crocodileand lungfish he could get his hands on.
The zoologist was enthusiastic about collecting animals, living and dead. While descending go inside In the ruins he saw his first mummies: ancient birds stacked like wine bottles in a cellar.
The ancient Egyptians revered many animals, including the ibis. To preserve the birds, they treated they dry salted and poured oil and resin over the remains before wrapping them and placing them in jars.
When Geoffroy returned from Egypt, he brought some of the packed ibises, cats, jackals, crocodiles and other animals with him. Cuvier was eager to investigate them. The mummification process worked so well that even some of the “smallest hairs‘were still intact.
When Cuvier compared the bones of long-dead ibises to modern birds, they looked very similar.
Lamarck agreed. But the mummies were only 3,000 years old. At the time, no one knew how old the planet was, but a few thousand years was “infinitesimally small‘ in the grand scheme of the earth, Lamarck said in a lecture to his students.
It would be strange to see a new species in a few millennia, he later wrote, “for the position and climate of Egypt are still almost what they were at that time.” It took both time and a unique environment to give rise to a new species, he thought.
However, Cuvier felt that his belief in the immutable nature of species was justified. “I have shown that it now looks exactly as it did in the time of the Pharaohs,” he later wrote of the mummified ibis. Time and climate were not enough to significantly change the species.
He was wrong, just as Lamarck was wrong about the mechanisms of heredity.
Darwin’s predecessor
The evidence from the mummies was not enough to overturn the case debate about transformism, despite Cuvier’s powerful reputation.
With the publication of Charles Darwin’s ‘On the Origin of Species’ in 1859, the whole debate flared up again, this time supported by the naturalist’s extensive observations and research.
More than twenty years after Lamarck’s death, Darwin called him as one of his predecessors, although he called his views ‘erroneous’. The creator of the theory of evolution by natural selection admitted he was far from the first to observe that ‘species undergo modification’.
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