When President Thomas Jefferson sent the Lewis and Clark expedition to explore the far west of the fledgling United States in 1804, he hoped it would return with tidings of live mastodons. Jefferson had long been an enthusiast of the massive fossils found at sites scattered throughout the known parts of his country. He had devoted time to the study of mastodons (then known as the American incognitum) even in the midst of the revolution and he believed the giants that had left their remains in the east still roamed the unexplored west. The expeditionâs failure to find any trace of fossil monsters helped to shatter some of Jeffersonâs core beliefs about nature, and brought him to accept one of the great scientific advances of his time: the discovery of extinction.
LIKE many prominent 18th-century thinkers, Thomas Jefferson believed in a perfect creation under divine supervision, in which no new kind of animal could come into being and no living species be destroyed. âSuch is the economy of nature,â he wrote, âthat no instance can be produced, of her having permitted any one race of her animals to become extinct; of her having formed any link in her great work so weak as to be broken.â
Just days after his inauguration as vice-president of the United States in March 1797, Jefferson addressed the American Philosophical Society about a fossil brought to him from a cave in what is now West Virginia. The heavy humerus and long lower-arm bones ended in a menacing claw 20 centimetres long. Jefferson believed he had the remains of a giant cat that might still rule Americaâs unknown wilderness. He named the fossil Megalonyx, or âgreat clawâ. As Meriwether Lewis and William Clark prepared for their expedition in 1803, Jefferson wrote to French naturalist Bernard LacĂŠpède that it âwas not improbableâ they would return with news of mammoths and Megalonyx.
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Jefferson treasured large fossils as evidence of his countryâs boundless potential. He used them to refute the insulting theory of the prominent French naturalist George Louis Leclerc, Comte de Buffon, who claimed that America was a continent of lesser life forms, smaller and weaker than their European counterparts. Buffon suggested that a malign American climate sapped the vigour of man and beast alike, and described native American men as small, feeble and lacking âactivity of mindâ.
These ideas were embraced and expanded by other Old World intellectuals, including AbbĂŠ Raynal, who believed that Europeans too dwindled physically and mentally under the dread influences of wild America. âOne must be astonished,â Raynal wrote, âthat America has not yet produced one good poet, one able mathematician, one man of genius in a single art or a single science.â
Buffon died in 1788, but a decade later, when Jefferson first studied the remains of Megalonyx, he was still intent on vanquishing the concept of âAmerican degeneracyâ. So he was predisposed to romanticise the fossil arm, seeing its owner as a fearsome lion.
While Jefferson conjured up images of giant-clawed predators roaming Americaâs interior, in France the great comparative anatomist Georges Cuvier was creating the science of palaeontology. From his detailed studies of fossil and modern bones, Cuvier showed that many of Jeffersonâs ideas were as baseless as Buffonâs. The giant cat, for instance, proved to be a lumbering, defunct form of sloth. Jefferson quickly saw his mistake in classifying that particular beast, but it was years before he accepted the radical concept that Cuvier read in the big bones: some creatures that once walked the Earth had vanished forever.
In 1796 Cuvier published a memoir on his studies of living and fossil elephants. He quietly advanced his revolutionary observation: the teeth and jaws of the American incognitum (which Cuvier named Mastodon) were distinct from those of living elephants, and so must belong to a creature that no longer existed.
Cuvier left the analysis of his findings to others. But in a paper written later that year on the skeleton of a giant South American sloth larger than any modern bear, Cuvier was bolder in asserting his discovery of a community of extinct creatures. âThe animals of the ancient world all differ from those we see on Earth today. For it is scarcely probable that, if this animal still existed, such a remarkable species could hitherto have escaped the researches of naturalists.â
In Europe, which had been tamed for millennia, Cuvierâs conclusion seemed reasonable, and by the turn of the 19th century he had persuaded most European naturalists that extinction was a reality. Cuvierâs most compelling arguments were based on studies of fossil mastodons, mammoths and sloths from America â specimens that in some cases Jefferson had supplied. Jefferson, however, clung to his belief that giants still walked in the unexplored parts of his country. âOur entire ignorance of the immense country to the west and north-west does not authorise us to say what it does not contain,â he maintained.
Jefferson accepted the idea of extinction after Lewis and Clark returned without a single mastodon sighting to report. In 1823, he wrote to his long-time friend John Adams: âWe see, too, evident proofs of the necessity of a superintending power to maintain the Universe in its course and order. Stars, well known, have disappeared, new ones have come into view ⌠certain races of animals are become extinct; and, were there no restoring power all existences might extinguish successively, one by one, until all should be reduced to a shapeless chaos.â
âJefferson believed that giants still walked in the American westâ
Lewis and Clark did discover many creatures unknown to science, including the grizzly bear, pronghorn antelope, prairie dog and mountain goat and wrote of âimmence herds of Buffaloe â. Even so, what they were seeing was an impoverished fauna that had lost all its largest creatures, says Paul Martin, a palaeoecologist at the University of Arizona.
In a mass extinction at the end of the Pleistocene, some 11,000 years before, America had lost five species of elephant, as well as camels and horses, the long-horned bison and the stag moose, and the dire wolves and sabre-toothed cats that preyed on them. Martin and many other researchers now believe that the continentâs first settlers were responsible for the great die-off, hunting big herbivores into oblivion.
Now, two centuries after Jefferson surrendered his vision of elephants roaming the west, some scientists are suggesting it is time to resurrect it. Martin is one of a group of conservation biologists and palaeontologists who envision a wildly unconventional way to compensate for the loss of Americaâs mega-mammals. They propose to introduce elephants and large predators from Africa and Asia to the Great Plains as proxies for extinct mammoths, mastodons and American lions and cheetahs. Add a few species of wild horse and a camel and you have something resembling the fauna that lived there before the arrival of humans.
Many conservationists think âPleistocene re-wildingâ, as its proponents call it, is crackpot. They point out that trying to restore dwindling populations of native species is itself an uphill struggle: the Great Plains remain empty of wild bison, and prairie dogs occupy only 5 per cent of their historic range. Yet others see the idea as an important recognition of the need to redress the ecological damage humans caused long before European settlers drove the bison and wolf to near-extinction.
But proponents of Pleistocene re-wilding argue that it is a means not just of restoring Americaâs ecosystems, but also of conserving large and iconic species that are at risk of extinction in their own lands. They are prepared to take radical steps to stop the slide towards a world everywhere diminished by human meddling â a 21st-century version of Jeffersonâs âshapeless chaosâ.
In their eyes, African savannah, where elephants and cheetahs struggle to survive, resembles pristine North America more closely than any of the American westâs existing parks or preserves. Itâs impossible to recreate a Pleistocene Eden, but a return of the giants to the American plains could help keep a slice of ancient biodiversity alive. âWe donât know whether ecosystems are fundamentally changed when the largest animals disappear,â says palaeoecologist Anthony Barnosky of the University of California, Berkeley. âSo itâs a good idea to make sure that ecosystems with big mammals donât vanish from the face of the Earth.â
