The Best American Science and Nature Writing 2014 (24 page)

“What has become of these two enormous animals of which one no longer finds any living traces?” Cuvier asked his audience. The question was more than rhetorical. Just a few months earlier, Cuvier had received sketches of a skeleton that had been discovered in Argentina. The skeleton was twelve feet long and six feet high; the sketches showed it to have sharp claws, flattish feet, and a short muzzle. On the basis of the sketches, Cuvier had identified its owner—correctly—as an oversized sloth. He named it
Megatherium
, meaning “great beast.” Though he had never been to Argentina or, for that matter, anywhere farther than Stuttgart, Cuvier was convinced that the
Megatherium
was no longer to be found lumbering through the jungles of South America. It, too, had disappeared. Like the mammoth's and the mastodon's, its bones hinted at events both strange and terrible. They “seem to me,” Cuvier said, “to prove the existence of a world previous to ours, destroyed by some kind of catastrophe.”

 

Extinction may be the first scientific idea that children today have to grapple with. We give one-year-olds dinosaurs to play with, and two-year-olds understand, in a vague sort of way, at least, that these small plastic creatures represent very large animals that once existed in the flesh. If they're quick learners, kids still in diapers can explain that there were once many kinds of dinosaurs and that they lived long ago. (My own sons, as toddlers, used to spend hours over a set of dinosaurs that could be arranged on a plastic mat depicting a forest from the Cretaceous. The scene featured a lava-spewing volcano, and when you pressed the mat in the right spot it emitted a delightfully terrifying roar.) All of which is to say that extinction strikes us as an extremely obvious idea. It isn't.

Aristotle wrote a ten-book
History of Animals
without considering the possibility that animals actually had a history. Pliny's
Natural History
includes descriptions of animals that are real and animals that are fabulous, but no descriptions of animals that are extinct. The idea did not crop up during the Middle Ages or during the Renaissance, when the word “fossil” was used to refer to anything dug up from the ground (hence the term “fossil fuel”). During the Enlightenment, the prevailing view was that every species was a link in a great, unbreakable “chain of being.” As Alexander Pope put it in his
Essay on Man:

 

All are but parts of one stupendous whole,

Whose body nature is, and God the soul.

 

When Carolus Linnaeus introduced his system of binomial nomenclature, he made no distinction between the living and the dead, because, in his view, none was required. The tenth edition of his
Systema Naturae
, published in 1758, lists sixty-three species of scarab beetle, thirty-five species of cone snail, and fifteen species of flat fish. And yet in the
Systema Naturae
there is really only one kind of animal—those that exist.

This view persisted despite a growing body of evidence to the contrary. Cabinets of curiosity in London, Paris, and Berlin were filled with traces of strange marine creatures that no one had ever seen—the remains of what would now be identified as trilobites, belemnites, and ammonites. Some of the last were so large that their fossilized shells approached the size of wagon wheels. But the seas were vast and mostly unexplored, and so it was assumed that the creatures must be out there somewhere.

With his lecture on “the species of elephants, both living and fossil,” Cuvier finally put an end to this way of thinking. Much as Charles Darwin is often credited with having come up with the theory of evolution—his real insight, of course, involved finding a mechanism for evolution—so Cuvier can be said to have theorized extinction.

Darwin's story has been recited (and re-recited) countless times by now. Entire books have been devoted to the few months he spent in Australia; to his mysterious and quite possibly psychosomatic illness; to the death of his oldest daughter; and to his decade-long study of barnacles. (This last subject is one that Darwin himself seems to have found tedious.) In 2009, when the two hundredth anniversary of Darwin's birth rolled around, the occasion was marked by scores of events, including an “evolution festival” in Vancouver, an uninterrupted reading of
On the Origin of Species
in Barcelona, and the construction of a massive Darwin doll for the Carnival parade in Recife. That same year, a full-length biopic, starring Jennifer Connelly as Darwin's wife (and first cousin), Emma, was released.

Cuvier, though, is very nearly forgotten. Many of his papers have still not been translated into English, and in studies of professional paleontology Cuvier is routinely slighted, even as he is acknowledged to be the founder of the discipline. Unless the situation changes dramatically, the two hundred fiftieth anniversary of his birth, in 2019, will pass without notice.

Darwin's work is inconceivable without Cuvier's discoveries. And yet Cuvier's obscurity is directly linked to Darwin's fame. Darwin's theory of extinction—that it was a routine side effect of evolution—contradicted Cuvier's, which held that species died out as a result of catastrophes, or, as he also put it, “revolutions on the surface of the earth.” Darwin's view prevailed, Cuvier's was discredited, and for more than a century Cuvier was ignored. More recent discoveries, however, have tended to support the theories of Cuvier's that were most thoroughly vilified. Very occasionally, it turns out, the earth has indeed been wracked by catastrophe and, much as Cuvier imagined, “living organisms without number” have been their victims. This vindication of Cuvier would be of interest mainly to paleontologists and intellectual historians were it not for the fact that many scientists believe we are in the midst of such an event right now.

 

Since Cuvier's day, the National Museum of Natural History has grown into a sprawling institution with outposts all over France. Its main buildings, though, are still in Paris, on the site of the old royal gardens in the Fifth Arrondissement. Cuvier worked at the museum for most of his life and lived there, too, in a large stucco house that's been converted into office space. Next door to the house, there's a restaurant, and next to that a menagerie, where, on the day I visited, some wallabies were sunning themselves on the grass. Across the gardens, a large hall houses the museum's paleontology collection.

Pascal Tassy is a professor at the museum who specializes in proboscideans, the group that includes elephants and their lost cousins—mammoths, mastodons, and gomphotheres, to name just a few. He'd promised to show me the bones that Cuvier had examined when he came up with the theory of extinction. I found Tassy in his dimly lit office in the basement under the paleontology hall, sitting amid a mortuary's worth of old skulls. The walls of the office were decorated with covers from old
Tintin
comic books. Tassy told me he decided to become a paleontologist when he was seven, after reading a Tintin adventure about a dig.

We chatted about proboscideans for a while. “They're a fascinating group,” he told me. “For instance, the trunk, which is a change of anatomy in the facial area that is truly extraordinary. It evolved separately five times. Two times—yes, that's surprising. But it happened
five
times, independently! We are forced to accept this by looking at the fossils.” So far, Tassy said, some 170 proboscidean species have been identified, going back some 55 million years. “And this is far from complete, I am sure.”

We headed upstairs to an annex attached to the back of the paleontology hall like a caboose. Tassy unlocked a small room crowded with metal cabinets. Just inside the door, partly wrapped in plastic, stood something resembling a hairy umbrella stand. This, he explained, was the leg of a woolly mammoth, which had been found, frozen and desiccated, on an island off Siberia. When I looked at it more closely, I could see that the skin of the leg had been stitched together like a moccasin. The hair was a very dark brown and seemed, even after more than ten thousand years, to be almost perfectly preserved.

Tassy opened one of the metal cabinets and placed its contents on a wooden table. These were some of the mastodon teeth that Cuvier had handled. The teeth had been found in the Ohio River Valley in 1739 by French soldiers, and, though they were there to fight a war, the soldiers had lugged the teeth down the Mississippi and put them on a boat to Paris.

“This is the
Mona Lisa
of paleontology,” Tassy said, pointing to the largest of the group. “The beginning of everything. It's incredible, because Cuvier himself made the drawing of this tooth. So he looked at it very carefully.” I picked it up in both hands. It was indeed a remarkable object. It was around 8 inches long and 4 across—about the size of a brick, and nearly as heavy. The cusps—four sets—were pointy, and the enamel was still largely intact. The roots, as thick as ropes, formed a solid mass the color of mahogany.

What particularly intrigued Cuvier about the mastodon teeth—and perplexed his predecessors—was that although they'd been found alongside a giant tusk, they didn't look anything like elephant teeth. Instead, they looked as though they could have belonged to an enormous human. (A mastodon molar that was sent to London in another eighteenth-century shipment was labeled “Tooth of a Giant.”) In evolutionary terms, the explanation for this is simple: about 30 million years ago, the proboscidean line that would lead to mastodons split off from the line that would lead to elephants and also mammoths. The latter would eventually develop its more sophisticated teeth, which have ridges on the surface rather than cusps. (This arrangement is a lot tougher, and it allows elephants—and used to allow mammoths—to consume an unusually abrasive diet.)

Mastodons, meanwhile, retained their relatively primitive molars (as did humans) and just kept chomping away. Of course, as Tassy pointed out, the evolutionary perspective is precisely what Cuvier lacked, which in some ways makes his achievements that much more impressive.

“Sure, he made errors,” Tassy said. “But his technical works—most of them are splendid. He was a real fantastic anatomist.”

After we had examined the teeth a while longer, Tassy took me up to the paleontology hall. Just beyond the entrance, a giant femur, also sent from the Ohio River Valley to Paris, was displayed, mounted on a pedestal. It was as wide around as a fence post. French schoolchildren were streaming past us, yelling excitedly. Tassy had a large ring of keys, which he used to open various drawers underneath the glass display cases. He showed me a mammoth tooth that had been examined by Cuvier, and bits of various other extinct species that Cuvier had been the first to identify. Then we looked at one of the world's most famous fossils, known as the Maastricht animal—an enormous pointy jaw studded with sharklike teeth. In the eighteenth century, the Maastricht fossil was thought by some to belong to a strange crocodile and by others to be from a snaggletoothed whale. Cuvier attributed it, yet again correctly, to a marine reptile. (The creature was later dubbed a mosasaur.)

Around lunchtime, I walked Tassy back to his office and then wandered through the gardens to the restaurant next to Cuvier's old house. Because it seemed like the thing to do, I ordered the Menu Cuvier—your choice of entrée plus dessert. As I was working my way through the second course—a cream-filled tart—I began to feel uncomfortably full. I was reminded of a description I had read of the anatomist's anatomy. During the revolution, Cuvier was thin. In the years he lived on the museum grounds, he grew stouter and stouter until, toward the end of his life, he became enormously fat.

 

With his lecture on “the species of elephants, both living and fossil,” Cuvier had succeeded in establishing extinction as a fact. But his most extravagant assertion—that there had existed a whole lost world, filled with lost species—remained just that. If there had indeed been such a world, then it ought to be possible to find traces of other extinct animals. So Cuvier set out to find them.

Paris in the 1790s was a fine place to be a paleontologist. The hills to the north of the city were riddled with quarries that were actively producing gypsum, the main ingredient of plaster of Paris. (The capital grew so quickly over so many mines that cave-ins were a major concern.) Not infrequently, quarriers came upon weird bones, which were prized by collectors even though they had no real idea what they were collecting. With the help of one such enthusiast, Cuvier soon assembled the pieces of another extinct animal, which he described as
l'animal moyen de Montmartre
—“the medium-sized animal from Montmartre.”

By 1800, four years after the elephant paper, Cuvier's fossil zoo had expanded to include twenty-three species that he deemed to be extinct. Among these were a pygmy hippopotamus, whose remains he found in a storeroom at the Paris museum; an elk with enormous antlers, whose bones had been found in Ireland; and a large bear—what now would be known as a cave bear—from Germany. The Montmartre animal had, by this point, divided, or multiplied, into six separate species. (Even today, little is known about these species except that they were ungulates and lived some 30 to 40 million years ago.) “If so many lost species have been restored in so little time, how many must be supposed to exist still in the depths of the earth?” Cuvier asked.

Cuvier had a showman's flair and, long before the museum employed public relations professionals, knew how to grab attention. (“He was a man who could have been a star on television today,” Tassy told me.) At one point, the gypsum quarries around Paris yielded a fossil of a rabbit-size creature with a narrow body and a squarish head. Cuvier hypothesized, based on the shape of its teeth, that the fossil belonged to a marsupial. This was a bold claim, as there were no known marsupials in the Old World. To heighten the drama, Cuvier announced that he would put his identification to a public test. Marsupials have a distinctive pair of bones, now known as epipubic bones, that extend from their pelvis. Though these bones were not visible in the fossil as it was presented to Cuvier, he predicted that if he scratched around, the missing bones would be revealed. He invited Paris's scientific elite to gather and watch as he picked away at the fossil with a fine needle. Voilà, the bones appeared. (A cast of the marsupial fossil is on display in Paris in the paleontology hall, but the original is deemed too valuable to be exhibited and is kept in a special vault.)