quinta-feira, 4 de abril de 2019

The Lost World

The mastodon’s molars.

On April 4, 1796—or, according to the French Revolutionary calendar in use at the time, 15 Germinal, Year IV—Jean-Léopold-Nicholas-Frédéric Cuvier, known, after a brother who had died, simply as Georges, delivered his first public lecture at the National Institute of Science and Arts, in Paris. Cuvier, who was twenty-six, had arrived in the city a year earlier, shortly after the end of the Reign of Terror. He had wide-set gray eyes, a prominent nose, and a temperament that a friend compared to the exterior of the earth—generally cool, but capable of violent tremors and eruptions. Cuvier had grown up in a small town on the Swiss border and had almost no connections in the capital. Nevertheless, he had managed to secure a prestigious research position there, thanks to the passing of the ancien régime, on the one hand, and his own sublime self-regard, on the other. An older colleague later described him as popping up in the city “like a mushroom.”

For his inaugural lecture, Cuvier decided to speak about elephants. Although he left behind no record to explain his choice, it’s likely that it had to do with loot. France was in the midst of the military campaigns that would lead to the Napoleonic Wars, and had recently occupied Belgium and the Netherlands. Booty, in the form of art, jewels, seeds, machinery, and minerals, was streaming into Paris. As the historian of science Martin J. S. Rudwick relates, in “Bursting the Limits of Time” (2005), a hundred and fifty crates’ worth was delivered to the city’s National Museum of Natural History. Included among the rocks and dried plants were two elephant skulls, one from Ceylon—now Sri Lanka—and the other from the Cape of Good Hope, in present-day South Africa.
By this point, Europe was well acquainted with elephants; occasionally one of the animals had been brought to the Continent as a royal gift, or to travel with a fair. (One touring elephant, known as Hansken, was immortalized by Rembrandt.) Europeans knew that there were elephants in Africa, which were considered to be dangerous, and elephants in Asia, which were said to be more docile. Still, elephants were regarded as elephants, much as dogs were dogs, some gentle and others ferocious. Cuvier, in his first few months in Paris, had examined with care the plundered skulls and had reached his own conclusion. Asian and African elephants, he told his audience, represented two distinct species.

“It is clear that the elephant from Ceylon differs more from that of Africa than the horse from the ass or the goat from the sheep,” he declared. Among the animals’ many distinguishing characteristics were their teeth. The elephant from Ceylon had molars with wavy ridges on the surface, “like festooned ribbons,” while the elephant from the Cape of Good Hope had teeth with ridges arranged in the shape of diamonds. Looking at live animals would not have revealed this difference, as who would have the temerity to peer at an elephant’s molars? “It is to anatomy alone that zoology owes this interesting discovery,” Cuvier said.

Having successfully sliced the elephant in two, Cuvier continued with his dissection. Over the decades, the museum had acquired a variety of old bones that appeared elephantine. These included a three-and-a-half-foot-long femur, a tusk the size of a jousting lance, and several teeth that weighed more than five pounds each. Some of the bones came from Siberia, others from North America. Cuvier had studied these old bones as well. His conclusions, once again, were unequivocal. The bones were the fragmentary remains of two new species, which differed from both African and Asian elephants “as much as, or more than, the dog differs from the jackal.” Moreover—and here one imagines a hush falling over his audience—both creatures had vanished from the face of the earth. Cuvier referred to the first lost species as a mammoth, and the second as an “Ohio animal.” A decade later, he would invent a new name for the beast from Ohio; he would call it a mastodon.

“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 Carl 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 which 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 bio-pic, 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- and-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 hundred and seventy proboscidean species have been identified, going back some fifty-five 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 eight inches long and four 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 labelled “Tooth of a Giant.”) In evolutionary terms, the explanation for this is simple: about thirty 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 awhile 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 shark-like 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 seventeen-nineties 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 thirty to forty 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 élite 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.)
Cuvier staged a similar bit of paleontological performance art during a trip to the Netherlands. In a museum in Haarlem, he examined a specimen that consisted of a large semicircular skull attached to part of a spinal column. The fossil, three feet long, had been discovered nearly a century earlier and had been attributed—rather curiously, given the shape of the head—to a human. (It had even been assigned a scientific name: Homo diluvii testis, or “man who was witness to the Flood.”) To rebut this identification, Cuvier first found an ordinary salamander skeleton. Then, as Rudwick relates it, he began chipping away at the rock around the deluge man’s spine. When he uncovered the fossil animal’s forelimbs, they were, just as he had predicted, shaped like a salamander’s. The creature was not an antediluvian human but something far weirder: a giant amphibian.

The more extinct species Cuvier turned up, the more the nature of the beasts seemed to change. Cave bears, giant sloths, even giant salamanders—all these bore some relation to species that were still alive. But what to make of a bizarre fossil that had been found in a limestone formation in Bavaria? Cuvier received an engraving of this fossil from one of his many correspondents. It showed a tangle of bones, including what looked to be extremely long arms, skinny fingers, and a narrow beak. The first naturalist to examine it speculated that its owner had been a sea animal and had used its elongated arms as paddles. Cuvier, on the basis of the engraving, determined—shockingly—that the animal was actually a flying reptile. He called it a ptero-dactyle, meaning “wing-fingered.”
Cuvier’s proof of extinction—of “a world previous to ours”—was a sensational event, and news of it soon spread across the Atlantic. When a nearly complete giant skeleton was unearthed by some farmhands in Newburgh, New York, it was recognized as a find of great significance. Vice-President Thomas Jefferson made several attempts to get his hands on the bones. He failed. But a friend, the artist Charles Willson Peale, who’d recently established the nation’s first natural-history museum, in Philadelphia, succeeded.

Peale, perhaps an even more accomplished showman than Cuvier, spent months fitting together the bones he acquired from Newburgh, fashioning the missing pieces out of wood and papier-mâché. He presented the skeleton to the public on Christmas Eve, 1801. To publicize the exhibition, Peale had his black servant, Moses Williams, don an Indian headdress and ride through the streets of Philadelphia on a white horse. The reconstructed beast stood eleven feet high at the shoulder and more than seventeen feet long from tusks to tail, a somewhat exaggerated size. Visitors were charged fifty cents—quite a considerable sum at the time—for a viewing.

The beast, an American mastodon, at this point still lacked an agreed-upon name, and was variously referred to as an incognitum, an Ohio animal, and, most confusing of all, a mammoth. It became America’s first blockbuster exhibit, and set off a wave of “mammoth fever.” The town of Cheshire, Massachusetts, produced a twelve-hundred-and-thirty-pound “mammoth cheese”; a Philadelphia baker produced a “mammoth bread”; and the newspapers reported on a “mammoth parsnip,” a “mammoth peach tree,” and a mammoth eater, who “swallowed 42 eggs in ten minutes.” Peale also managed to piece together a second mastodon, out of additional bones found in Newburgh and a nearby town in the Hudson Valley. After a celebratory dinner held underneath the animal’s capacious rib cage, he dispatched this second skeleton to Europe with two of his sons, Rembrandt and Rubens. The skeleton was exhibited for several months in London, during which time the younger Peales decided that the animal’s tusks must have pointed downward, like a walrus’s. Their plan was to take the skeleton on to Paris and sell it to Cuvier. But while they were in London war broke out between Britain and France, making travel between the two countries impossible.
Cuvier finally gave the mastodonte its name in a paper published in Paris in 1806. The peculiar designation comes from the Greek, meaning “breast tooth”; the cusps on the animal’s molars apparently reminded him of nipples.
Despite the ongoing hostilities between the British and the French, Cuvier managed to obtain detailed drawings of the skeleton that Peale’s sons had taken to London, and these gave him a much better picture of the animal’s anatomy. He realized that the mastodon was far more distant from modern elephants than the mammoth was, and assigned it to a new genus. (Today, mastodons are given not only their own genus but their own family.) In addition to the American mastodon, Cuvier identified four other mastodon species, all “equally strange” to the earth today. Peale didn’t learn of Cuvier’s new name until 1809, and when he did he immediately seized on it. He wrote to Jefferson proposing a “christening” for the mastodon skeleton in his Philadelphia museum. Jefferson was lukewarm about the name Cuvier had come up with—it “may be as good as any other,” he replied—and didn’t deign to respond to the idea of a christening.
In 1812, Cuvier published a four-volume compendium of his work on fossil animals—“Recherches sur les Ossemens Fossiles de Quadrupèdes.” Before he began his “researches,” there had been zero vertebrates classified as extinct. Thanks for the most part to his own efforts, there were now at least forty-nine.
As Cuvier’s list grew, so did his renown. Few naturalists dared to announce their findings in public until he had vetted them. “Is not Cuvier the greatest poet of our century?” Balzac asked. “Our immortal naturalist has reconstructed worlds from a whitened bone; rebuilt, like Cadmus, cities from a tooth.” Cuvier was honored by Napoleon and, once the Napoleonic Wars finally ended, was invited to Britain, where he was presented at court.
The English were eager converts to Cuvier’s project. In the early years of the nineteenth century, fossil collecting became so popular among the upper classes that a whole new vocation sprang up. A “fossilist” was someone who made a living hunting up specimens for rich patrons. The year Cuvier published his “Recherches,” one such fossilist, a young woman named Mary Anning, discovered a particularly outlandish specimen. The creature’s skull, found in the limestone cliffs of Dorset, was nearly four feet long, with a jaw shaped like a pair of needle-nose pliers. Its eye sockets, peculiarly large, were covered with bony plates.
The fossil ended up in London at the Egyptian Hall, a privately owned museum not unlike Peale’s. It was put on exhibit as a fish and then as a relative of a platypus before being recognized as a new kind of reptile—an ichthyosaur, or “fish-lizard.” A few years later, other specimens collected by Anning yielded pieces of another, even wilder creature, dubbed a plesiosaur, or “almost-lizard.” Oxford’s geology expert, the Reverend William Buckland, described the plesiosaur as having a lizardlike head joined to a neck “resembling the body of a Serpent,” the “ribs of a Chameleon, and the paddles of a Whale.” Apprised of the find, Cuvier found the account of the plesiosaur so outrageous that he questioned whether the specimen had been doctored. When Anning uncovered another, nearly complete plesiosaur fossil, Cuvier had to acknowledge that he’d been wrong. “One shouldn’t anticipate anything more monstrous to emerge,” he wrote to one of his British correspondents. During Cuvier’s trip to England, he visited Oxford, where Buckland showed him yet another astonishing fossil—an enormous jaw with one curved tooth sticking up out of it like a scimitar. Cuvier recognized this animal, too, as some sort of lizard. A couple of decades later, the jaw was identified as belonging to a dinosaur.
The study of stratigraphy was in its infancy at this point, but it was already understood that different layers of rocks had been formed during different periods. The plesiosaur, the ichthyosaur, and the as yet unnamed dinosaur had all been found in limestone deposits that were attributed to what was then called the Secondary and is now known as the Mesozoic era. So, too, had the ptero-dactyle and the Maastricht animal. This pattern led Cuvier to another extraordinary insight about the history of life: it had a direction. Lost species whose remains could be found near the surface of the earth, like mastodons and cave bears, belonged to orders of creatures that were still alive. Dig back further and one found creatures, like the animals from Montmartre, that had no obvious modern counterparts. Keep digging, and mammals disappeared altogether from the fossil record. Eventually, one reached not just a world previous to ours but a world previous to that, dominated by giant reptiles.
Cuvier’s ideas about this history of life—that it was long, mutable, and full of fantastic creatures that no longer existed—would seem to have made him a natural advocate for evolution. But he opposed the concept of evolution, or transformisme, as it was known in Paris at the time, and he tried—generally, it seems, successfully—to humiliate any colleagues who advanced the theory. Curiously, it was the same skills that led him to discover extinction that made evolution appear to him preposterous, an affair as unlikely as alchemy.
As Cuvier liked to point out, he put his faith in anatomy; this was what had allowed him to distinguish the bones of a mammoth from those of an elephant and to recognize as a giant salamander what others took to be a man. At the heart of his understanding of anatomy was a notion that he termed “correlation of parts.” By this, he meant that the components of an animal all fit together and are optimally designed for its particular way of life; thus, a carnivore will have an intestinal system suited to digesting flesh. Its jaws will be “constructed for devouring prey; the claws, for seizing and tearing it; the teeth, for cutting and dividing its flesh; the entire system of its locomotive organs, for pursuing and catching it; its sense organs for detecting it from afar.”
Conversely, an animal with hooves must be an herbivore, since it has “no means of seizing prey.” It will have “teeth with a flat crown, to grind seeds and grasses,” and a jaw capable of lateral motion. Were any one of these parts to be altered, the functional integrity of the whole would be destroyed. An animal that was born with, say, teeth or sense organs that were somehow different from its parents’ would not be able to survive, let alone give rise to an entirely new kind of creature.

In Cuvier’s day, the most prominent proponent of transformisme was his senior colleague at the National Museum of Natural History, Jean-Baptiste Lamarck. According to Lamarck, there was a force—the “power of life”—that pushed organisms to become increasingly complex. At the same time, animals and also plants often had to cope with changes in their environment. They did so by adjusting their habits; these new habits, in turn, produced physical modifications that were then passed down to their offspring. Birds that sought prey in lakes spread out their toes when they hit the water, and eventually developed webbed feet and became ducks. Moles, having moved underground, stopped using their sight, and so over generations their eyes became small and weak. Lamarck adamantly opposed Cuvier’s idea of extinction; there was no process he could imagine that was capable of wiping an organism out entirely. (Interestingly, the only exception he entertained was humanity, which, Lamarck allowed, might be able to exterminate certain large and slow-to-reproduce animals.) What Cuvier interpreted as espèces perdues Lamarck claimed were simply those that had been most completely transformed.
The notion that animals could change their body types when convenient Cuvier found absurd. He lampooned the idea that “ducks by dint of diving became pikes; pikes by dint of happening upon dry land changed into ducks; hens searching for their food at the water’s edge, and striving not to get their thighs wet, succeeded so well in elongating their legs that they became herons or storks.” He discovered what was, to his mind at least, definitive proof against transformisme in a collection of mummies.
When Napoleon invaded Egypt, the French, as usual, seized whatever interested them. Among the crates of loot shipped back to Paris was an embalmed cat. Cuvier examined the mummy, looking for signs of transformation. He found none. The ancient Egyptian cat was, anatomically speaking, indistinguishable from a Parisian alley cat. This proved that species were fixed. Lamarck objected that the few thousand years that had elapsed since the Egyptian cat was embalmed represented “an infinitely small duration” relative to the vastness of time.
“I know that some naturalists rely a lot on the thousands of centuries that they pile up with a stroke of the pen,” Cuvier responded dismissively. Eventually, he was called upon to compose a eulogy for Lamarck, which he did very much in the spirit of burying rather than praising. Lamarck, according to Cuvier, was a fantasist. Like the “enchanted palaces of our old romances,” his theories were built on “imaginary foundations,” so that, while they might “amuse the imagination of a poet,” they could not “for a moment bear the examination of anyone who has dissected a hand, a viscus, or even a feather.”
Having dismissed transformisme, Cuvier was left with a gaping hole. He had no account of how new organisms could appear, or any explanation for how the world could have come to be populated by different groups of animals at different times. This doesn’t seem to have bothered him. His interest, after all, was not in the origin of species but in their demise.
The very first time he spoke about the subject, Cuvier intimated that he knew the driving force behind extinction, if not the exact mechanism. In his lecture on elephants, he proposed that the mastodon, the mammoth, and the Megatherium had all been wiped out “by some kind of catastrophe.” Cuvier hesitated to speculate about the precise nature of the calamity—“It is not for us to involve ourselves in the vast field of conjectures that these questions open up”—but, at that point, he seems to have believed that one disaster would have sufficed.

Later, as his list of extinct species grew, his position changed. There had, he decided, been multiple cataclysms. “Life on earth has often been disturbed by terrible events,” he wrote. “Living organisms without number have been the victims of these catastrophes.”

Like his view of transformisme, Cuvier’s belief in cataclysm fit with—indeed, could be said to follow from—his convictions about anatomy. Since animals were functional units, ideally suited to their circumstances, there was no reason, in the ordinary course of events, that they should die out. Not even the most devastating events known to occur in the contemporary world—volcanic eruptions, say, or forest fires—were sufficient to explain extinction; confronted with such changes, organisms simply moved on and survived. The changes that had caused extinctions must therefore have been of a much greater magnitude—so great that animals had been unable to cope with them. That such extreme events had never been observed by him or any other naturalist was another indication of nature’s mutability: in the past, it had operated differently—more intensely and more savagely—than it did at present.

“The thread of operations is broken,” Cuvier wrote. “Nature has changed course, and none of the agents she employs today would have been sufficient to produce her former works.” Cuvier spent several years studying the rock formations around Paris—together with a mineralogist friend, he produced the first stratigraphic map of the Paris Basin—and here, too, he saw signs of cataclysmic change. The rocks showed that, at various points, the region had been submerged. The shifts from one environment to another—from marine to terrestrial, or, at some points, from marine to freshwater—had, Cuvier decided, “not been slow at all”; rather, they had been brought about by those sudden “revolutions” on the surface of the earth. The latest of these revolutions must have occurred relatively recently, for traces of it were still everywhere apparent. This event, Cuvier believed, lay just beyond the edge of recorded history; he observed that many ancient myths and texts, including the Old Testament, allude to some sort of crisis—usually a deluge—that preceded the present order.

Cuvier’s ideas about a globe wracked periodically by cataclysm proved to be nearly as influential as his original discoveries. His major essay on the subject, which was published in Paris in 1812, was almost immediately reprinted in English and exported to America. It also appeared in German, Swedish, Italian, and Russian. But a good deal was lost, or, at least, misinterpreted in translation. Cuvier’s essay was pointedly secular. He cited the Bible as merely one of many ancient texts, alongside the Hindu Vedas and the Shujing. This sort of ecumenism was unacceptable to the Anglican clergy who made up the faculty at institutions like Oxford, and when the essay was translated into English it was construed by Buckland and others as offering proof of Noah’s flood.
By now, the empirical grounds of Cuvier’s theory have largely been disproved. The physical evidence that convinced him of a “revolution” just prior to recorded history (and that the English interpreted as proof of the Deluge) was in reality debris left behind by the last glaciation. The stratigraphy of the Paris Basin reflects not sudden “irruptions” of water but, rather, gradual changes in sea level and the effects of plate tectonics. On all these matters, Cuvier was, we now know, wrong.

Yet his wildest-sounding claims have turned out to be surprisingly accurate. Cataclysms happen. Nature does, on occasion, “change course,” and at such moments it is as if the “thread of operations” has been broken. The contemporary term for these cataclysms is “mass extinctions,” and the geological record suggests that, in the past half billion years, there have been five major ones and a dozen or more lesser ones. In the most severe of the so-called Big Five, at the end of the Permian period, some two hundred and fifty million years ago, something like ninety per cent of all species died off, and multicellular life came perilously close to being obliterated altogether. In the most recent, at the end of the Cretaceous, the dinosaurs were wiped out, along with the mosasaurs, the pterosaurs, the plesiosaurs, the ammonites, and two-thirds of all families of mammals, all in what, geologically speaking, amounted to an instant.

Meanwhile, as far as the American mastodon is concerned, Cuvier was to an almost uncanny extent correct. He decided that the beast had disappeared five or six thousand years ago, in the same “revolution” that had killed off the mammoth and the Megatherium. Actually, the American mastodon vanished around thirteen thousand years ago, in a wave of disappearances that has become known as the megafauna extinction. This wave coincided with the spread of modern humans, and, increasingly, is understood to have been a result of it. Humans are now so rapidly transforming the planet—changing the atmosphere, altering the chemistry of the oceans, reshuffling the biosphere—that many scientists argue that we’ve entered a whole new geological epoch: the Anthropocene. In this sense, the crisis that Cuvier discerned just beyond the edge of recorded history was us. ♦
(This is the first part of a two-part article.)
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