Written in Stone: Evolution, the Fossil Record, and Our Place in Nature

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Written in Stone: Evolution, the Fossil Record, and Our Place in Nature Page 21

by Brian Switek


  —GILBERT IMLAY, Topographical Descriptions of the Western Territory, 1792

  The war was finally over. On September 3, 1783, representatives of the American Congress of the Confederation and a delegation representing King George III of England signed the Treaty of Paris, formally bringing an end to the war for American independence that had begun in 1775. It would take more than seven months until both parties had ratified the agreement, but by then the cannonade and musket fire that shook the nascent American nation had long ceased. With the war for freedom over, the United States of America now had to fight for the respect of the European powers that had allied with it and fought against it during the previous decade.

  Careful political maneuvering was pivotal to fostering the growth of the United States, but science would also have a role to play. This would bring one of America’s Founding Fathers, the polymath Thomas Jefferson, into direct conflict with one of the greatest naturalists of France, Georges-Louis Leclerc, Comte de Buffon. In this intellectual battle, in which natural history had everything to do with national pride, facts from zoology and paleontology would be essential elements in the arsenals of both parties.

  Buffon had fired the opening shot even before the onset of the American Revolution. The research required to write his great, multivolume series Historie naturelle had acquainted Buffon with the varied natural productions of the world, but when he looked from the Old World to the New he noticed a great disparity. The New World had none of the impressive animals that had for so long captivated the European imagination. In the ninth volume of the series, published in 1761, Buffon wrote of the Americas,In general, all the animals there are smaller than those of the old world, & there is not any animal in America that can be compared to the elephant, the rhinoceros, the hippopotamus, the dromedary [camel], the giraffe, the buffalo, the lion, the tiger, etc.

  Not only that, but in Buffon’s estimate the Americas were not even capable of supporting such prodigious beasts. The New World was a hemisphere marked by degeneracy, proved by the fate of the robust domestic animals European settlers had introduced to North America. They did not flourish, and Buffon suspected that an inhospitable climate was to blame for the corruption of the European breeds. Buffon pointed out that the most magnificent animals were found in hot, equatorial regions. Clearly the warm temperatures better stimulated the production of life, and Buffon reinforced his hypothesis with evidence from prehistory. Despite its present relatively cool climate, the petrified bones of tropical animals such as elephants, hippos, big cats, and rhinos had been discovered in western Europe. (The remains of the elephants were sometimes argued to have belonged to war elephants brought into Europe by conquering Romans during antiquity, but the same explanations could not be applied to the other animals.) Apparently they had flourished during a past time when Europe was much warmer.

  Buffon explained this climate change in his 1778 tome, Epoques de la nature. After conducting experiments with globes made of various metals that were heated white hot and then left to cool, Buffon proposed that the world was formed in a molten state and had been slowly cooling ever since.59 The fossil hippos, lions, rhinos, and other tropical beasts had inhabited Europe during a time when the world was still relatively warm but their ranges had subsequently shrunk as the earth continued to cool. That the New World did not harbor animals of equal stature meant that it was unlikely that they were present during the past, suggesting that it had always been a brutish, infertile place devoid of the great natural wonders of the Old World. And if this was the state of the natural world, what would become of the colonists who chose America as their home? Would they, too, degenerate into an inferior society?

  FIGURE 65 - Thomas Jefferson painted in 1800 by artist Rembrant Peale.

  Thomas Jefferson could not abide this insult. It mattered little that, after conversing with Benjamin Franklin on science, Buffon changed his views on American degeneracy. The New World, and North America in particular, was often denigrated as being inferior to Europe. Jefferson was driven to prove that America was as glorious, as wonderful a land as any other.

  Jefferson documented the natural richness of America, along with his views on politics and society, in Notes on the State of Virginia, a book that had its roots in a list of questions that had been given to representatives of each of the thirteen colonies by the secretary of the French delegation to the United States. The responsibility for responding on behalf of Virginia eventually found its way to Jefferson. Published in France in 1784, the book was his minutely detailed response to the French government and Buffon alike. Among the various descriptive passages was data on the size of North American animals like bear and deer, and though some of the reports were inflated (like domestic cows weighing over a ton), Jefferson provided ample evidence that America was just as vigorous and stimulating as anywhere else in the world.

  Jefferson sent a copy of Notes and the skin of an exceptionally large cougar to Buffon. This was enough to gain him an invitation to dine with the French naturalist at the city’s botanical garden, the Jardin du Roi. In conversation Jefferson found Buffon almost entirely unfamiliar with the large animals of America, and Jefferson soon wrote back to General John Sullivan, the governor of New Hampshire, asking that the skin and bones of the largest moose that could be found be sent directly to him in Paris.60

  But the moose was not the biggest animal that Jefferson herded into supporting his case for American robustness. Though no one had seen one alive, there were rumors that an even larger animal still roamed the largely uncharted expanses of the American interior. The only sign that it had ever existed were enormous bones, many of which had been found at what would come to be known as “Big Bone Lick,” in Jefferson’s home state of Virginia.61

  The graveyard of the enormous beasts in the Virginia backcountry had come to the attention of Europeans several decades before. In 1735, a small group of French-Canadian soldiers were marching from Quebec toward New Orleans with their Native American allies from the Abenaki tribe (who actually made up the bulk of the fighting force of over 400 men). Under the command of Charles le Moyne, their mission was to drive back the Chickasaws, a tribe allied with the English, who were threatening New Orleans and had made passage toward the port city along the Mississippi all but impossible.

  By summer the force was heading southwest along what is now known as the Ohio River. It was too long a trip to be covered by packed provisions, so Abenakis were often dispatched from the group to bring back game. One night, at dusk, as the army was camped along the river not far beyond where the city of Cincinnati, Ohio, would one day be founded, the hunters brought back not only meat, but several enormous teeth, a femur nearly as tall as they were, and dark-colored tusks. The bones were not entirely unfamiliar to the Abenakis. Their legends told of ancient monsters vanquished by heroes, enormous elk, and water monsters. The French-Canadian soldiers did not believe these stories, but recognized that the bones might be valuable and carried them along.

  Eventually the army arrived at their destination on the rim of the Gulf of Mexico, and from there in 1740 Charles le Moyne brought the fossil bones with him to France. When the French anatomist Louis Daubenton presented his conclusions about the fossils to the French Royal Academy in 1762, he asserted that the bones belonged to at least two different animals. Clearly the tusk and the femur belonged to some kind of elephant, but the molars, similar to the molars of hippos from Africa, seemed better suited to pulverizing flesh and bone than grinding grass.62 This would give any would-be explorers of North America’s interior cause for alarm, since both the elephant and the meat-eating hippo probably still lurked somewhere in the American wilderness.

  That this type of molar tooth and tusks had often been found together led Jefferson to doubt Daubenton’s assessment, but he did agree that the species was still alive somewhere west of the Mississippi. “Such is the economy of nature,” Jefferson wrote, “that no instance can be produced of her having permitted any one race of her animals
to become extinct; or her having formed any link in her great work so weak as to be broken.”

  FIGURE 66 - The molar tooth of an American mastodon, originally known as the “American Incognitum.” The rough bumps and ridges of the teeth led some eighteenth and nineteenth century naturalists to believe that the mastodon was a carnivore.

  Jefferson could also appeal to the fact that many Native American tribes, including the Abenakis, passed down legends about monstrous creatures bigger than the biggest bison. The only conclusion could be that Native Americans had seen them during recent history, though where the creatures had gone was unknown. Even so, if the “American Incognitum” was still alive then it certainly rivaled or surpassed even the largest animals of the Old World. Jefferson could not provide a living specimen or its pelt, but he could convincingly use it to deflect any remaining remarks about American “degeneracy.”

  Jefferson was not only interested in the animal for political reasons. He was an avid naturalist and was fascinated by fossils. That the Incognitum might still live only added to the mystery of the Louisiana Territory, which Jefferson acquired for the United States during his first presidential term in 1803. When Jefferson sent Meriwether Lewis and William Clark to explore the purchased land, among other things he told them to keep an eye out for the lumbering Incognitum as well as any interesting fossils that he could add to his collection in what would become the East Room of the White House.

  If Lewis and Clark did bump into the elephantine beast, naturalists believed, they would be lucky to escape with their lives. It was generally agreed that the molars and tusks of the kind Moyne found belonged to one animal, but Daubenton’s interpretation that the molars indicated an animal of carnivorous habits stuck. This interpretation was most colorfully argued by the naturalist George Turner during a 1799 meeting of the American Philosophical Society in Philadelphia. Said Turner of the carnivorous elephant:May it not be inferred, too, that as the largest and swiftest quadrupeds were appointed for his food, he necessarily was endowed with great strength and activity? That, as the immense volume of the creature would unfit him for coursing after his prey through thickets and woods, Nature had furnished him with the power of taking it by a mighty leap? - That this power of springing a great distance was requisite to the more effectual concealment of his bulky volume while lying in wait for his prey?

  The image of a rapacious, bone-crushing elephant leaping out of the woods onto deer, bison, and even humans stretched credulity, but such were the ways of nature.63 If the Incognitum had teeth well suited to shearing flesh, then the rest of its body and habits would have been fine-tuned to make it a successful hunter. The existence of such a creature was not cruel but a sign of the beneficence of God or Nature. Such predators weeded out the old and the sick, and great appetites could not exist without the means to fill them.

  FIGURE 67 - The nearly complete skeleton of an American mastodon, as figured in Cuvier’s description of fossil elephants.

  Turner’s vision of the Incognitum was not to last. As the polymath Benjamin Franklin commented when he saw the hefty molars of the beast in 1768, such teeth “might be as useful to grind the small branches of Trees, as to chaw Flesh.” Debate on this point went back and forth for years, but it was eventually determined that the creature was an herbivore and not a bloodthirsty elephant. It crushed tree branches in its jaws rather than limb bones. Even so, this did not change the interpretation that it was a creature perfectly molded by nature that would not be allowed to disappear. It would be Georges Cuvier who would destabilize the “economy of nature” that other naturalists of the time fervently believed in.

  By the close of the eighteenth century several ill-defined species of elephant were recognized. There were the living African and Asian varieties, the American Incognitum, and another type of fossil elephant often found in the permafrost of Siberia. This latter animal, like its American counterpart, was surrounded by myth and legend, but the bones were often thought to have belonged to one of the living types that had wandered further north when the world was still warm.

  In 1796, Cuvier set about determining, once and for all, whether these types separated by time and space were really just one species or several. He presented his results in what would become a landmark paper, “Memoirs on the Species of Elephants, Both Living and Fossil.” Incredibly, Cuvier concluded that each type was a distinct species. Through comparative anatomy he was able to determine that the African and Asian elephants were distinct from each other, and the fossil types differed just as strongly. The North American creature, identified by the breastlike bumps of its teeth, would later be named Mastodon by Cuvier. The creature from Siberia, on the other hand, would be called the mammoth, and Cuvier’s identification would be supported three years later when the Russian botanist Mikhail Ivanovich Adams discovered the skeleton of a mammoth—with tatters of flesh still clinging to it—near the mouth of the Lena River in Siberia. While the mammoth showed some resemblance to the Asian elephant, Adams’s specimen revealed that the living animal had been covered in a coarse, shaggy coat that seemed better adapted to the modern frozen tundra than the past global hothouse Buffon had proposed. What puzzled naturalists, however, is where these elephants had come from and what had become of them.

  The bones of the mastodon and the mammoth were both found in places elephants did not inhabit in Cuvier’s time, and none of the traditional explanations for this disparity held up to scrutiny. No staunch biblical literalist would like to admit that Noah had decided to leave some species behind, and the bones were too different from those of living species to make credible Buffon’s proposal that they were the remains of living species that had once inhabited different parts of the world during warmer times. Likewise, it was difficult to take seriously Jefferson’s belief that such animals might still be living in unexplored parts of the globe. In an age of expansion, exploration, and empire there were few places left in the world for such large animals to hide. Extinction was the only reasonable explanation for the pattern Cuvier saw:All these facts, consistent among themselves, and not opposed by any report, seem to me to prove the existence of a world previous to ours, destroyed by some kind of catastrophe. But what was this primitive earth? What was this nature that was not subject to man’s dominion? And what revolution was able to wipe it out, to the point of leaving no trace of it except some halfdecomposed bones?

  This was a bold statement for the young anatomist to make. Even though the concept that there might be “lost species” had been toyed with previously, Cuvier had finally presented evidence for it.

  While Cuvier’s belief that there was nowhere left for previously unknown large animals to hide was premature, those who held out hope that prehistoric species might still be found had their faith eroded by the discovery of even stranger fossil creatures. Among other distinct fossil species Cuvier also described the crocodilelike “Monster of Maastricht” he called Mosasaurus and an enormous sloth from Buenos Aires, Argentina, he christened Megatherium.64

  Even Jefferson reconsidered the disappearance of species. In an 1823 letter to his friend and rival, John Adams, Jefferson couched extinction within his belief of an orderly, regulated natural universe.

  It is impossible, I say, for the human mind not to believe that there is, in all this, design, cause and effect, up to an ultimate cause, a fabricator of all things from matter and motion, their preserver and regulator while permitted to exist in their present forms, and their regenerator into new and other forms. We 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, comets, in their incalculable courses, may run foul of suns and planets and require renovation under other laws; 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 shapeless chaos.

  Though beautiful, the universe was not perfect, and
in Jefferson’s view it required some preserving force to fix what had become damaged and replace what had been lost. Whatever this force was, whether it was deity or natural law, it acted as a tinkerer, never putting things back exactly as they were.

  With the science of paleontology established, European naturalists began to search their own backyards for more fossils. What they found was that their countries were founded upon vast accumulations of elephant bones. Where living and fossil types had been lumped into one species, there was now an explosion of proposed extinct types, such as a predecessor to the mammoth, Elephas meridionalis, and another widespread form, Elephas priscus. Cuvier and his English counterpart Richard Owen doubted the validity of some of these new species, but even so, the abundance of extinct elephants in Europe was remarkable.

  Even more fossil elephants were found in distant territories controlled by European powers. In 1830, the young botanist and paleontologist Hugh Falconer left England to act as an assistant surgeon for the British East Asia Company in India. While most of his time was occupied by his duties as a doctor, or in the botanical gardens at Suharunpoor, when he had a few moments to spare he picked up the fossils that littered the nearby Siwalik Hills. Many of the deposits Falconer traversed were Cenozoic in age, or represented the Age of Mammals which succeeded the previous age in which reptiles swarmed over the globe. Falconer was hardly the first to find fossils here. Local legends held that the bones of giants were embedded in the hills, and like the bones found by the Abenakis along the Ohio River these remains had come from numerous prehistoric elephants. Falconer wrote:What a glorious privilege it would be, could we live back—if only for an instant—into those ancient times when the extinct animals peopled the earth! To see them all congregated together in one grand natural menagerie—these Mastodons and Elephants, so numerous in species, toiling their ponderous forms trumpeting their march in countless herds through the swamps and reedy forests!

 

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