Thomas Jefferson’s mammoth problem


Author of the Declaration of Independence, creator of the University of Virginia, a Founding Father and third president of the USA, Thomas Jefferson was a pioneer. Of this, you are undoubtedly aware. And, like most pioneers, Jefferson fostered an interest in virtually every aspect of science. This appetite for knowledge propelled him to organise the Lewis and Clark Expedition into the then-uncharted western area of the continent, brought under American governance by the Louisiana Purchase, which took place during his presidency. Considered an expert in civil engineering, anatomy, architecture, anthropology, physics, mechanics, meteorology, navigation, ethnology, botany and geography, it is not surprising that Jefferson was also a pioneer in our own field – palaeontology.

“Science is my passion,” Thomas Jefferson wrote, “politics is my duty”. It could almost be said that he was as much of a pioneer in science as in law and politics – indeed, although we may remember his political pursuits as his most historically-resonant, his scientific achievements were pretty admirable. “Nature intended me for the tranquil pursuits of science,” he wrote, “rendering them my supreme delight.” Christopher Hitchens thought that, were Jefferson born a decade later, he would have been one of the finest palaeontologists in history. However, as it was, Jefferson was still looking at mountains and asking how shells got so high up on the mountaintop.

The side project of many an eighteenth century American scientist was the study of mysterious teeth, bones and seven-foot tusks yielded by swamps and riverbeds. Millions of years of American history had been spent occupied by mighty mastodon and mammoths until the Pleistocene era, and they left plenty of forensic evidence in their wake. However, this knowledge was lost to the colonists. A giant molar “the size of a man’s fist” was discovered by a farmer in 1705, who promptly traded it with a politician in exchange for a bottle of rum. The politician sent it to Lord Cornbury, who described it as the “tooth of a Giant” following Biblical evidence. This “monstrous creature” became known as an ‘incognitum’ or an unknown species.


When similar teeth later turned up in South Carolina, slaves pointed out that they looked a lot like an African elephant’s. Early explorers also brought back whole tusks and bones from the Ohio River Valley. Americans soon started referring to the original incognitum as a “mammoth”, after the woolly mammoths then being dug out of the ice in Siberia. As it happened, the North American continent had been home to two similar species of pachyderm – the mastodon and the mammoth – and no one at the time knew the difference between them. Anatomists in Europe (at the request of Jefferson) were able to compare the incognitum with existing specimens, so the year 1806 saw French naturalist Georges Cuvier distinguish between the mastodon – a distant relative of the elephant – and the mammoth. In Paris, the incognitum became something of an attraction. Eminent men from all around visited – including the American ambassador, Benjamin Franklin, who suggested that the mastodon’s huge tusks would be an impediment when chasing prey, but its piercing molars would be useful “to grind the small branches of Trees”. Franklin, in this regard, was correct – the mammoth lived in Siberian grasslands, where its flat teeth were used to eat grass, but the mastodon came from the leafy forest areas east of the Mississippi River.

For Jefferson, the incognitum proved not only a fascinating creature. It also provided ammunition for him to deal the final blow in a scientific war against the eminent naturalist, the Comte de Buffon, who had suggested the ecology of the American continent had a degenerative effect on animals, which produced inferior, weaker species. Native Americans, Buffon wrote, were stupid, lazy savages, who degenerated for the same reason that animals did – the cold and the humidity.

These claims may as well have been engineered specifically to irritate Jefferson: proving de Buffon wrong became his great obsession while governing Virginia, through the War of Independence and as an ambassador in France. The statesman responded with a put-down in his Notes on the State of Virginia, stating sarcastically that de Buffon believed it was “as if both sides [of the globe] were not warmed by the same genial sun”. When visiting France, he brought with him a panther skin – but none of this could compare to the argument Jefferson made with his use of palaeontological evidence.

His refutation of de Buffon was made decisive by Jefferson sending to France a fossilised skeleton of the mastodon – a 2.5m tall behemoth that Europe surely could not match. Jefferson’s gift was not merely altruism – it was a declaration of the superiority of the New World over the Old – and consolidated palaeontology’s position as a respectable science in the newly-formed USA.

Comte de Buffon’s ‘theory of American degeneracy’ still influenced (and infuriated) Jefferson during his presidency. He soon sent Lewis and Clark on their expedition west. Along with many contemporaries, Thomas Jefferson believed that it was impossible for a species to become extinct. He expressed this idea in his “great chain of being”, which stated that nature was “finely-balanced” in such a way as to ensure all species existed permanently. “Such is the economy of nature, that no instance can be produced of her having permitted any one race of her animals to become extinct;” he wrote, “of her having formed any link in her great work so weak as to be broken.” As a result, when Lewis and Clark set out west, Jefferson asked them to keep one eye open for any living mastodon.

One of Lewis and Clark’s stops on their journey westward was in Ohio, where the explorers sent back mastodon fossils from Big Bone Lick. Unfortunately, these were lost in transit, but Jefferson did not stop there. In 1807, he financed William Clark’s return to Big Bone Lick, in the hope that he would find head and foot bones to complete Charles Wilson Peale’s mastodon exhibition.


The Founding Father made other contributions to palaeontology throughout his life. In 1796, Jefferson received some bones from Colonel John Stuart (including a femur fragment, an ulna, radius and foot bones). During his vice-presidency, he set to work on the bones and presented his analysis of them to the American Philosophical Society in Philadelphia. His paper theorised that these “Certain Bones” were that of an animal similar to the lion, which he named Megalonyx, or ‘giant claw’. Sticking to his long-held belief in the non-existence of extinction, Jefferson also made sure that Lewis and Clark would look out for his lion-like Megalonyx on their 1804-1806 expedition, insisting that it could still be found out west.

His analysis was entirely incorrect. In reality, the Megalonyx is more like a three-metre tall, one-thousand-kilogram giant sloth, with highly-developed claws for stripping leaves and branches off trees. However, when Dr Caspar Wistar discovered this in 1822, he remembered to secure Jefferson’s work on the Megalonyx for posterity by renaming the species Megalonyx jeffersonii. M. jeffersonii is still the most frequently found species of Megalonyx today.


Jefferson designed his house, Monticello, himself; and the great entrance-hall was soon filled with mastodon skeletons. During his White House years, the East Room was packed with an impressive collection of mastodon fossils strewn across the floor, as Jefferson dedicated himself to the mystery of the mastodon. However, perhaps Jefferson’s main contribution to the science was the introduction of vertebrate palaeontology to the fledgling USA, which still thrives today.


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