by Brian Switek
FIGURE 7 - The skeleton of the Buenos Aires Megatherium.
At the time, however, it could not be understood just how old these formations were. Their relative age could be determined by the succession of fossils, but their absolute age was a mystery.9 Hence Smith’s work focused on the correspondence between fossils and the strata that contained them, and this helped him to produce brilliant geological maps of England. Unfortunately, however, Smith did not have an academic sponsor to speak for him when his work was plagiarized, and this made it so difficult for Smith to make a living that he was eventually cast into the debtor’s prison at King’s Bench. It was not until 1819 that he was able to continue work as a surveyor in an attempt to eke out a living, and it would take another decade before his work would be recognized by his geological colleagues.
Like Smith, Cuvier also recognized the close association between fossils and divisions of time. In 1808, he and his peer Alexandre Brongniart published a report called “Essay on the Mineral Geography of the Paris Region,” in which they observed that the order of the strata surrounding the city could be understood by the distribution of fossils within the rock. The transitions were a little messy, specific forms were not locked just into one layer alone, but certain species showed spikes of prevalence only to dwindle in the next successive layer before disappearing entirely. This method worked over and over again for the identification of geological time and thus meant that fossils could be reliably used to not only differentiate between vast periods of ancient time but to separate one thin slice of earth history from another.
This allowed Cuvier and Brongniart to determine that the area around Paris had been subject to alternating inundation by seawater and freshwater on the basis of invertebrate fossils contained in the surrounding strata. Changes occurred cyclically but Cuvier considered them to have a more punctuated pattern than the steady state world Hutton proposed. The sea had rushed in, remained for a time, then quickly receded and was replaced by freshwater before the cycle started again. Such rapid change would surely destabilize environments and cause extinctions, so this regular alternation of catastrophic events could explain the various fossil accumulations, cordoned off by barriers of extinction, which Cuvier saw.
Cuvier most explicitly outlined the role of catastrophes during the earth’s history in his 1812 book Ossemens fossiles, a synthesis of the work he had begun two decades earlier. In the “Preliminary Discourse” that prefaced the work, Cuvier pontificated on the pattern of ruin and reform over time, and he identified the most recent catastrophe as occurring about 6,000 years ago. Cuvier derived this figure from looking at archaeological and historical evidence. In 1799 the French expedition that recovered the Rosetta Stone also found the mummified remains of birds and other animals in the tombs of Egypt. When carefully examined, these animals—though thousands of years old—were revealed to be identical to their living counterparts, confirming that the last great upheaval had happened before they lived. On the basis of such evidence, Cuvier concluded:In this revolution the countries in which men and the species of animals now best known previously lived, sank and disappeared; that conversely it laid dry the bed of the previous sea, and made it into the countries that are now inhabited; that since that revolution the small number of individuals spared by it have spread out and reproduced on the land newly laid dry; and that consequently it is only since that time that our societies have resumed progressive course, that they have formed institutions, erected monuments, collected facts of nature, and combined them into scientific systems.
Simply put, some parts of the previous world sank below the sea while today’s continents were thrust out of the water in almost an instant, and the few survivors of the last geological revolution repopulated the planet. New life did not spring up in the wake of extinction, but life was already present and migrated into new areas.
This was not a biblically based argument. Though Cuvier was a Protestant, he kept religion out of his scientific work. Even so, his discussion of a catastrophe, most likely caused by an encroaching sea during the last 6,000 years, was all too easily co-opted by those in England who required that geology conform to religious strictures.
Shortly after it was published in French, the “Preliminary Discourse” was translated into English under the title Essay on the Theory of the Earth by Robert Jameson, a Scottish naturalist who subscribed to the idea known as Neptunism which held that the earth’s rocks had precipitated out of oceans.10 The biblical Flood fit well with this geological view, and through a new introduction, end notes, and several revised editions Jameson asserted that Cuvier’s work supported the reality of a Deluge that had wiped the world clean during recent history. Jameson’s English translation introduced readers to Cuvier as what we would currently call a young earth creationist.11
But Jameson’s co-option of Cuvier’s “Preliminary Discourse” was not the only resource drawn upon to marry the science of geology and Christian theology. William Buckland was a Church of England reverend who was a popular lecturer in geology and paleontology at the time Cuvier’s introduction was translated into English. He had a deep love and respect for scripture, yet he was not exactly a literalist. He was perfectly comfortable with the idea that the world’s age was inestimably longer than the 6,000 years of biblical chronologies but he was steadfast on the historicity of Biblical events. Buckland believed that there certainly had been a Flood, but it would have been so short that almost no sign of it could be seen in the geological column.12
Still, Buckland was willing to change his ideas in the face of new evidence. In 1822 he began to investigate the fossil bones of Kirkdale Cave in Yorkshire. Many of those bones bore tooth marks and were scattered among a collection of chalk-white coprolites, or fossilized feces—sure signs that the cave had once been a hyena den. To confirm that cave hyenas were responsible for this damage Buckland devised a simple, but ingenious, experiment. Working with their keeper, he gave bones to the hyenas of a local zoo and compared the marks the living hyenas made with the ones of the ancient bones. Through the comparison of the fossil bones with the freshly chewed bones and the collection of prehistoric poop, Buckland was able to conclusively demonstrate that the hyenas had actually lived inside the cave during some ancient period and had not just been washed in by the Deluge.
It was a simple discovery, but during a ceremony awarding Buckland the Copely medal for his work, the president of the Royal Society, Humphry Davy, said it presented “a point fixed from which our researches may be pursued through the immensity of ages.” Encouraged by his peers, Buckland continued his research into the world before the Flood. He presented these findings in his 1823 work Reliquiae diluvianae, or, Observations on the Organic Remains Attesting the Action of a Universal Deluge.
In “Relics of the Deluge,” Buckland strained to find balance between two different sets of expectations. The idea that the Deluge had done most of the work in forming the present world was no longer taken seriously by most naturalists, yet Buckland believed that there was evidence for such an event. Caves filled with mammal bones were like time capsules that preserved a record of life before the catastrophe. Once the makeup of this lost fauna was identified their remains could be traced across the countryside, and often these bones were found in deposits of gravel, sand, and clay—materials that were easily transported by water. The bones of hippos, rhinos, lions, hyenas, and elephants in these “superficial deposits” attested to a recent inundation, Buckland believed, which replaced the tropical climate with a milder one.
FIGURE 8 - In a cartoon drawn by his friend Henry de la Beche, a young William Buckland uses the light of science to unravel the mysteries of Kirkdale Cave.
The weakness of Buckland’s hypothesis, however, was that he had presumed that all the cave strata and gravel deposits he examined were of the same age and therefore recorded a single event. As these deposits were probed further it was discovered that they had been formed at different times, and despite his book’s popularity its con
clusions were contested.13 The geological pattern did not appear to follow the hurryup-and-wait cycle of stability punctuated by disasters, and it was at this time that Hutton’s view of a cyclical, orderly earth was coming out of hibernation.
The geological revolutions of naturalists such as Cuvier and Buckland required geological events so devastating as to be almost supernatural. Everyone knew of floods, but no one had ever recorded one continent becoming inundated while another rose from the sea. Faced with this dilemma, some geologists began to return to Hutton’s view of ongoing, gradual change.14 The Scottish geologist Charles Lyell, through his three-volume series Principles of Geology, would become the champion of this idea and transform the discipline.
FIGURE 9 - A portrait of Charles Lyell, drawn later in his life.
Lyell proposed that while the earth was constantly in flux it was also in balance. A river might erode rock and transport it to the sea, but this destruction was counteracted by volcanoes spewing new rock onto the surface. Every geological process had its counterpart, and the planet was constantly reforming itself in a slow and steady fashion. In the introduction to chapter five of the first volume of Principles of Geology, published in 1830, Lyell wrote:The first observers conceived that the monuments which the geologist endeavours to decipher, relate to a period when the physical constitution of the earth differed entirely from the present, and that, even after the creation of living beings, there have been causes in action distinct in kind or degree from those now forming part of the economy of nature. These views have been gradually modified, and some of them entirely abandoned in proportion as observations have been multiplied, and the signs of former mutations more skilfully interpreted. Many appearances, which for a long time were regarded as indicating mysterious and extraordinary agency, are finally recognized as the necessary result of the laws now governing the material world; and the discovery of this unlooked for conformity has induced some geologists to infer that there has never been any interruption to the same uniform order of physical events. The same assemblage of general causes, they conceive, may have been sufficient to produce, by their various combinations, the endless diversity of effects, of which the shell of the earth has preserved the memorials, and, consistently with these principles, the recurrence of analogous changes is expected by them in time to come.
Even the terrifying earthquake was simple a mechanism by which the earth’s uniformity could be maintained. “This cause, so often the source of death and terror to the inhabitants of the globe, which visits, in succession, every zone, and fills the earth with monuments of ruin and disorder,” Lyell wrote, “is, nevertheless, a conservative principle in the highest degree, and, above all others, essential to the stability of the system.”
But Lyell knew that he not only had to show why he was right but why the opposition, naturalists who favored Cuvier’s “revolutions,” were wrong. There was no reason to think that geological phenomena had been more severe in the past than now, and Jameson’s biblically tinged translation of Cuvier’s work allowed Lyell to cast those who favored changes caused by catastrophes as fundamentalists who read scripture too narrowly. Through a rereading of evidence and force of argument, Lyell fostered the view of earth history Hutton had conceived three decades before.
As the earth changed, however, so did life. Paleontologists had clearly shown that the life of the past was different from that of the present, and if the movements of planets and the shifting of the earth proceeded by natural laws then the formation of life should be no different. Hutton himself had considered this in his immense, three-volume monograph of 1794 called An Investigation of the Principles of Knowledge. He wrote:If an organised body is not in the situation and circumstances best adapted to its sustenance and propagation, then, in conceiving an indefinite variety among the individuals of that species, we must be assured, that, on the one hand, those which depart most from the best adapted constitution, will be most liable to perish, while, on the other hand, those organised bodies, which most approach to the best constitution for the present circumstances, will be best adapted to continue, in preserving themselves and multiplying the individuals of their race.
The culling of organisms ill-adapted to their local conditions would cause species to become altered over the course of generations—but Hutton did not ascribe much power to this mechanism. Despite the Creator’s benevolence in allowing organisms to become adapted to shifting conditions there was no reason to think that these changes ever lead to the origin of new species. Some variation and change was expected, but all according to a set of natural laws that maintained the created order.
Naturalists on the continent, and specifically in France, had been willing to go a bit further than Hutton. There were most certainly orderly natural laws that affected biological entities, but they could cause those forms to break the boundaries that were thought to limit what a species might become. The most prominent exponent of this view was Seven Years War veteran Jean-Baptiste Lamarck.
Lamarck had not initially set out to be a naturalist. His family had a strong military tradition, and at the age of sixteen he joined the French army to battle Prussia. Despite his age he was quickly commissioned as an officer, but when one of his fellow soldiers lifted Lamarck up by his head during horseplay it caused the young officer’s lymphatic glands to become inflamed. Lamarck had to go to Paris for treatment, and afterward he was given a quiet, but not very well-paid, post in Monaco. Then, after a failed bout studying medicine, Lamarck turned his attention to botany. Both on his own and under the tutelage of the French naturalist Bernard de Jussieu, Lamarck familiarized himself with the flora of France, culminating in his 1778 book Flora française.
FIGURE 10 - Jean-Baptiste Lamarck in his later years.
This work drew the attention of Paris’s established naturalists, and by 1781 Lamarck was named the Royal Botanist at the Jardin du Roi (which was renamed the Jardin des Plantes in 1790). But Lamarck’s interests were not restricted to plants. He trained himself as a specialist in invertebrates, too, and during the closing years of the eighteenth century he began to study the fossil shells found around Paris.
The shells were different from, but still similar to, modern forms he was familiar with, and Lamarck believed that it would not take much to turn one form into another. Yet he went even further than this. In 1800 he presented a lecture on invertebrates at the Muséum national d’Histoire naturelle in which he proposed that all forms of life had been derived from earlier, simpler forms. Organisms achieved this through their interactions with the environment, hence producing the close fits between animals and the habitats they were found in. The webbed feet of some waterfowl had been produced in such a way:The bird which necessity drives to the water to find there the prey needed for its subsistence separates the toes of its feet when it wishes to strike the water and move on its surface. The skin, which unites these toes at their base, contracts in this way the habit of extending itself. Thus in time the broad membranes which connect the toes of ducks, geese, etc., are formed in the way indicated.
It was the habits of the animals that resulted in their form, not the form that dictated function, and these changes gained over the life of an individual were transmitted to the offspring of that animal. Yet as Lamarck continued to consider evolution, this acquisition of traits through habit or willpower became only the mechanism for a greater trend Lamarck saw in the history of life. In his most comprehensive presentation of his views of evolution, his 1809 book Philosophie zoologique , Lamarck pointed out that life appeared to be progressive, and the simplest life was always being pushed up a ladder of complexity. As new simple life forms spontaneously arose the mechanism of acquired characteristics came into play, and the habits of the organisms determined their progress up the evolutionary ladder; today’s monads could be tomorrow’s humans. New life, and hence potential new forms, were always being formed, and if extinction happened at all it was rare.
Lamarck’s evolutionary hypothesis was not very we
ll received. Lamarck’s contemporary Georges Cuvier was staunchly opposed to it, as it ran against the more systematized view of biology Cuvier had struggled to build. Whereas Lamarck thought form was dictated by function and extinction almost never happened, Cuvier asserted that function and form were tied together in a static package, and the evidence was clear that creatures did go extinct. If they did not, then what had the Megatherium and mammoth transformed into? Lamarck seems to have been aware of this difficulty—as he stated that extinction might happen among large, slow-breeding vertebrates—but in general he denied extinction for a vision of nature in which life was continuously moving from lower to higher without being extinguished.
The tension between Lamarck’s and Cuvier’s views was not so much about evolution as conflicting philosophies about how nature could be understood. In England, however, Lamarck’s view was seen as a materialistic proposal that directly contradicted the belief that divine wisdom was manifested in nature. The idea of a progression of organisms from more primitive to more advanced types was especially troubling, but in applying geological principles to living creatures Lyell thought he had found a way out. Clearly organisms were well matched to the environments in which they existed, but if the earth was in a constant, gradual state of flux then those habitats would not be permanent. As the geology of the planet changed, so would environments and the creatures in them, and given enough time the world might rearrange itself into a state approximating that of the age of the dinosaurs. During such a time, Lyell proposed, it would be expected that extinct creatures would reappear to reprise the roles they had fulfilled so long before: We might expect, therefore, in the summer of the “great year,” which we are now considering, that there would be a great predominance of tree-ferns and plants allied to palms and arborescent grasses in the isles of the wide ocean, while the dicotyledonous plants and other forms now most common in temperate regions would almost disappear from the earth. Then might those genera of animals return, of which the memorials are preserved in the ancient rocks of our continents. The huge iguanodon might reappear in the woods, and the ichthyosaur in the sea, while the pterodactyle might flit again through umbrageous groves of tree-ferns.
