Cuvier's Revolutions of the Globe

Cuvier portrait
Georges Cuvier
(after Cuvier, 1825)

Georges Cuvier (1769-1832), born and raised among French-speaking Protestants in the Duchy of Württemberg, entered the scientific world in Paris as an outsider. However, with talent and ambition he rapidly advanced to become one of France's greatest scientists. He effectively founded the science of Paleontology, established the principles of comparative anatomy and redefined our understanding of the variety of animal life.

Cuvier wasn't the first to contemplate the existence of a pre-human past, nor was he the first to accept extinction, but he was spectacularly capable of marshalling the facts and making the case for former worlds and lost species. Moreover, he demonstrated the existence of successive fossil faunas from within a given locality. Cuvier had identified himself as an "antiquire d'un sepece nouvelle" (new species of antiquarian), who would reveal the past through the examination of fossils.

Early versions of Cuvier's findings and interpretations of past worlds, extinct species and faunal successions could be found in several of his public lectures and numerous journal articles, but the most cohesive, accessible and widely disseminated source was his Discours préliminaire (Preliminary Discourse). This essay first appeared as the introductory section of his 1812 compilation Reserches sur les ossemens fossiles de quadrupedes (Research on the Fossil Bones of Quadrupeds). Evidently written to reach a general audience, Discours préliminaire was quickly recognized as a masterwork that soon reached a wider, international audience. For instance, despite the Napoleonic wars, an English translation of Cuvier's Discourse was published the following year (1). A German version appeared in 1816 and an American edition appeared in 1819. Revised versions of Discours préliminaire appeared in subsequent editions of Ossemens fossiles de quadrupedes , and in 1826, Cuvier sanctioned the separate publication that was re-titled Discours sur les revolutions de la surface du globe (Discourse on the Revolutions of the Surface of the Globe).

Early in Discours preliminaire, Cuvier sets the stage for the revelation of an unsuspected and tumultuous past:

"When a traveler crosses fertile plains, where the regular course of tranquil rivers sustains abundant vegetation, and where the land —crowded with numerous people and ornate with flourishing villages, rich cities, and superb monuments— is never disturbed by the ravages of war or by the oppression of powerful men, he is not tempted to believe that nature has also had its civil wars, and that the surface of the globe has been upset by successive revolutions and various catastrophes. But these ideas change as soon as he seeks to excavate this ground that today is so peaceful, or climb onto the hills that border the plain (2)."

geologic strata
Idealized cross section of the Paris Basin
(after Cuvier, 1812)

Cuvier and his contemporaries had discovered a geological world characterized by discontinuous and abrupt transitions between layers of sedimentary rock. Many of the layers were thick and relatively uniform with respect to their physical characteristics and the types of fossils contained therein. They apparently represented extended and rather tranquil episodes. However, these layers were commonly overlain by strikingly different layers that contained totally different sets of fossils. In many cases, these layers would alternate between marine and terrestrial/freshwater sediments. Moreover, the transition from one layer to the next was typically abrupt.

In addition to each layer (or stratum) having different sets of fossils, there was an apparent directionality in the type of fossils present, at least with respect to quadrupeds (3). The fossil viviparous quadrupeds (mammals) in surficial deposits (e.g., mastodons and mammoths) were similar to but different from modern forms. Go deeper and the quadrupeds become less and less similar to modern forms. For instance, Curvier and his collaborator Alexandre Brogniart (1770-1840) recovered mammalian fossils from a gypsum stratum near Paris that were strikingly different from modern species (4). Go even deeper and you'll only find oviparous quadrupeds (reptiles) (5).

The sharply delineated and often alternating marine and terrestrial strata combined with the apparent directionality in quadruped fossils led Cuvier to conclude that the earth had been subjected to repeated "revolutions", some of which were severe or catastrophic enough to lead to the extinction of whole fossil faunas. In other words, the history of life was characterized by periods of relative tranquility terminated by widespread and possibly global catastrophes:

"Living organisms without number have been the victims of the catastrophes. Some were destroyed by deluges, others were left dry when the seabed was suddenly raised; their races are even finished forever, and all they leave in the world is some debris that is hardly recognizable to the naturalist."

Paleotherium fossil
Nearly complete skeleton of
Paleotherium minus from the Paris Basin
(after Cuvier, 1825)

Unlike uniformitarians such as James Hutton (6), Cuvier could not accept the idea that these revolutions were caused by current geological processes such as erosion and volcanoes. To him, they simply couldn't explain the massive and abrupt changes he found in geologic strata. "The thread of operations is broken; nature has changed course, and none of the agents she employs today would have been sufficient to produce her former works."

Cuvier also saw evidence for extraordinary processes in the extinctions of whole faunas. In contrast with his contemporary Lamarck, he was committed to the idea that species were immutable (7). Cuvier regarded animals to be highly integrated, functional machines. This concept, which led to his famous "correlation of parts" (8), precluded the possibility of transformation (or evolution).

"Every organized being forms a whole, a unique and closed system, in which all the parts correspond mutually, and contribute to the same definitive action by a reciprocal reaction. None of its parts can change without the others changing too; and consequently each of them, taken separately, indicates and gives all the others. "

Erosion, floods, landslides and volcanic eruptions simply couldn't explain the disappearance of a successful, resilient and highly functional species, much less to the disappearance entire faunas. Something extraordinary, something beyond human experience, must have caused the extinctions.

Although he was a confirmed Lutheran Christian, Cuvier did not invoke Divine intervention to explain the causes of the catastrophes nor the appearance of successive faunas. He did, however, speculate that some regions may have escaped any given catastrophe and served as a source for repopulating the globe. On the other hand, some of Cuvier's disciples proposed multiple creations —Divine or otherwise— to explain the appearance of successive fossil faunas.

Cuvier guessed that the unusual mammalian fossils that he and Brogniart recovered from the gypsum stratum in the Paris Basin were"thousands of centuries" old. The last revolution, the direct indications of which lie in surficial deposits, was obviously much more recent. Cuvier took the recent discoveries of frozen carcasses of a woolly mammoth and rhinoceros as evidence that this revolution was very sudden. The loss of such giants as the mammoth, woolly rhinoceros, mastodon and ground sloths indicated that it was severe and widespread.

At the time he wrote Discours préliminaire Cuvier saw no evidence that humans existed before the last revolution. However, he acknowledged the possibility that they had existed in some isolated refuge and subsequently recolonized the globe. A variety of ancient texts, ranging from Hebrew to Egyptian to Chinese, indicated or at least suggested to Cuvier an historical memory of a massive deluge. Given an emerging consensus among European scholars of the age of these ancient civilizations, he concluded that it probably occurred as recently as 4000-5000 years ago (9):

". . . the surface of our globe has been the victim of a great and sudden revolution, the date of which cannot reach back much more that five or six thousand years; that 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 beds 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 a progressive course, that they have formed institutions, erected monuments, collected facts about nature, and combined them into scientific systems."

The preliminary nature of Discours préliminaire is emphasized in the last section of Cuvier's essay. He cites the need to clearly define and circumscribe the revolutions he sees in the geological and fossil records. Moreover, he regards the discovery of the cause of these events to be "an enterprise of quite another difficulty." He acknowledges that the study of the Paris Basin has provided only a very limited window onto the past. He calls on others to further the study of the past by investigating other promising European localities, which he laments, still lack systematic geological and paleontological study.

Discours préliminaire was arguably Cuvier's last major effort in paleontology; subsequent editions of his Researches on Fossil Bones and Preliminary Discourse were essentially expanded and/or revised versions of the earlier works. Much of his subsequent research was devoted to the comparative anatomy and classification of the animal kingdom. The book that resulted from this monumental endeavor, Le regne animal (1817 & 1829-30), radically altered the understanding of animal diversity by demolishing the Scala Naturae (10) . An increasingly greater amount of Cuvier's time was taken up in administrative and official duties.

As intended, Discours préliminaire inspired and informed a generation of paleontologists and biologists, including Gideon Mantell, Richard Owen and Charles Darwin in Britain, and Samuel Morton, Richard Harlan and Joseph Leidy in the United States (11). Ironically, as the sciences of paleontology and geology matured, Curvier's ideas about catastrophes and immutable species became discredited. Nonetheless, his reputation stands as the first of "new species of antiquarian" with the methods to reveal prehistory.

Websites:

Print Resources:

  • Cadbury, D. 2000. Terrible Lizard: the First Dinosaur Hunters and the Birth of a New Science. New York: Henry Holt. Originally published as The Dinosaur Hunters. 2000. London: Fourth Estate.
  • Carey, S.W. 1988. Theories of the Earth and Universe: A History of Dogma in the Earth Sciences. Stanford: Stanford University Press.
  • Cohen, C. 2002. The Fate of the Mammoth: Fossils, Myths and History. Translated by William Rodarmor. Chicago: University of Chicago Press. Originally published as Le Destin du Mammouth. 1994. Paris: Editions du Seuil.
  • Cuvier, Georges. 1812. Recherches sur les ossemens fossiles de quadrupèdes, òu l'on rétablit les caractères de plusieurs espèces d'animaux que les révolutions du globe paroissent avoir détruites. 4 vol. Paris: Deterville.
  • Cuvier, Georges. 1813. Essay on the theory of the earth, with minerological notes, and an account of Cuvier's geological discoveries by Professor Jameson. Edinburgh. Facimile reprint, NewYork: Arno, 1978.
  • Cuvier, Geoges. 1817. Le Règne animal distribué d'après son organisation, pour servir de base à l'histoire naturelle des animaux et d'introduction a l'anatomie comparée. 4 vol. Paris: Deterville.
  • Cuvier, Georges. 1825. Recherches sur les ossemens fossiles : où l'on rétablit les charactères de plusieurs animaux dont les révolutions du globe ont détruit les espèces. Paris: G. Dufour et E. d'Ocagne.
  • Gould, S.J. 2002. The Structure of Evolutionary Theory. Cambridge, London: Harvard Univeristy Press.
  • Lyell, Charles. 1830-33. Principles of Geology: or The Modern Changes of the Earth and Its Inhabitants as Illustrative of Geology, 3 vol. London: Murray.
  • Mayr, E. 1982. The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Cambridge, London: Harvard University Press.
  • Repcheck, J. 2003. The Man Who Found Time: James Hutton and the Discovery of Earth's Antiquity. Cambridge: Perseus Publishing.
  • Rudwick, M.J.S. 1997. Georges Cuvier, Fossil Bones and Geological Catastrophes: new translations. Chicago: University of Chicago Press.

Notes:

  • Robert Jameson (1775-1854) was responsible for the 1813 English translation of Cuvier's Discours préliminaire. Jameson was a professor of geology at Edinburgh University and founder of the Natural History Society. Jameson was a staunch Neptunist; Neptunism is a body of theory articulated by Abraham Gottleib Werner (1749-1817) in which the earth was an essentially inactive body, while most of the surface rocks originated as chemical precipitates from either a universal primeval ocean or subsequently fluctuating seas. Jameson also used his translation of Cuvier's Preliminary Discourse to argue for the historicity of the Biblical Deluge.

    Subsequent British and American editions of Preliminary Discourse were based on Jameson's translation and as such retained his editorial bias. Ironically, Jameson's version bore the title Essay on the theory of the earth. Cuvier was harshly critical of the numerous "Theories of the Earth" written by geologists, naturalists and natural theologians during the 18th and early 19th century. He dismissed them as great bodies of theory pursuing a scarcity of facts. [go back]
  • All of the Cuvier quotations on this page are from Rudwick (1997) except for those provided in footnote 7. [go back]
  • Quadruped (= four legs) is an archaic classification for four-legged vertebrates. Common usage was typically restricted to four-legged mammals (i.e., mammals exclusive of whales, dolphins, manatees and bats), but naturalists usually included several non-mammalian forms. Most reptiles and amphibians were included as oviparous quadrupeds (egg-laying quadrupeds), while mammalian quadrupeds (excluding monotremes) were classified as viviparous quadrupeds.

    Cuvier regarded terrestrial quadrupeds to be the most useful fossil animals for elucidating the past. He considered their presence in a stratum was unequivocal evidence of terrestrial environments and their disappearance from the succeeding strata as unequivocal evidence of extinction. The basis for his contention was that quadrupeds were substantially less diverse than invertebrates and fishes and were thus much more knowable. Although new quadrupeds were discovered from time to time, such discoveries were rare in comparison to the number of unknown non-quadrupeds. Indeed, many naturalists claimed that representatives of fossil marine invertebrates could still be found somewhere in the vast and largely unexplored oceans. [go back]
  • The Paris Basin study, conducted by Cuvier and Brogniart in the first decade of the 19th century, was a landmark study of geology. It involved a region-wide systematic study of the physical characteristics of the geological column and introduced the innovative use of fossils to identify strata, assign them relative ages and determine their depositional environment. Another study, conducted by William Smith (1769-1839) in Britain, also employed fossils to help identify and age strata. Working at about the same time, but independently of Cuvier and Brognairt, "Strata Smith" used "index fossils" to correlate strata separated by considerable distances. He published the first geological map for a large region (England, Wales and part of Scotland) in 1815.

    The strata studied by Cuvier and Brogniart extended from very old marine chalks to relatively recent surficial deposits; Contemporary geologic ages had yet to be defined, but we would now recognize the chalk stratum to be Cretaceous in age while the surficial deposits would date to the Pleistocene. Most of the strata contained either marine or freshwater invertebrate fossils, but vertebrates were found in two stratigraphic units. The Pleistocene deposits contained "the bones of elephants, oxen, antelopes and other large mammals". The gypsum stratum, which we can now date to the late Eocene, contained an assortment of mammals strikingly different from modern species. These included several species of Paleotherium , a genus belonging to long-extinct odd-toed ungulates (perissodactyls) related to early horses. Another well-represented genus, Anoplotherium, belonged to a primitive group of even-toed ungulates (artiodactyls). Cuvier also reported on a marsupial mammal from the gypsum beds that he considered as similar to the New World opossum (Didelphis). [go back]
  • Cuvier wrote, " . . . it is certain that oviparous quadrupeds appeared much sooner than the viviparous." No quadrupeds were found in the marine chalk that formed the deepest layer of the Paris Basin. But this formation —now assigned to the Cretaceous— extends through much of Western Europe. The most famous vertebrate fossil found within the chalk was the "crocodile of Maastrict" (the Netherlands), which Cuvier identified as a giant marine lizard (later named Mosasaurus). He was also familiar with the fossils of other "oviparous quadrupeds" (reptiles) found in strata older than (i.e., below) the Cretaceous chalks; these older strata are now assigned to the Jurassic and Permian.

    Cuvier's contention would be confirmed by discoveries made contemporaneously with or shortly after the publication of Discours préliminair. The fossils of two large marine reptiles, Ichthyosaurus and Plesiosaurus , were discovered by Mary Anning (1799-1847) in 1811 and 1823, respectively, and were formerly described in 1821 and 1824, respectively. Gideon Mantell (1790-1859) published on the discovery of the dinosaur Iguanodon in 1825. [go back]
  • James Hutton (1726-1796) was the leading theorist for a school of geology referred to as Plutonism. In contrast to Werner's Neptunism, Hutton argued in his Theory of the Earth (1785) that heat from the interior of the earth played the central role in forming and shaping of rocks and the landscape. He also articulated the core concept of uniformitarianism: current processes can account for all geological phenomena if one accepts an extremely old age for the earth. Uniformitarianism found its most memorable expression in the phrase "the present is the key to the past", which was written by Charles Lyell (1797-1875) in his masterwork The Principles of Geology (1830-32).

    The dichotomy between uniformitarianism and catastrophism is often overstated. For instance, Hutton believed that the earth's history consisted of cycles of extended and relatively tranquil episodes of erosion and sedimentation interrupted by catastrophic periods of uplift and mountain building. Lyell, on the other hand, argued for gradualism in nearly all geologic processes (i.e., uplifting and mountain building occurred over extended periods rather than in short, violent episodes).

    On the other hand, both Hutton and Lyell (and later Darwin) argued that the geologic and fossil record was inherently imperfect; erosion eliminated many strata and created unconformities in the geologic column. In contrast, Cuvier and Brogniart were literal empiricists. They accepted the sharp transitions between marine and terrestrial strata they found in the Paris Basin as evidence of a catastrophic changes between an ocean floor to emergent land. Lyell and company would see gaps in the sedimentary record. [go back]
  • Jeane Baptiste Pierre Antone de Monet, Chevalier de Lamarck (1744-1829) was Cuvier's colleague and rival. Although he has often been ridiculed by modern authors for his theory of acquired characteristics, he was arguably the first consistent evolutionist. His belief in the gradual transformation of species was apparently developed following his study of fossil and modern marine mollusks, many of which could be convincingly arranged in chronological series ending with modern species. Lamarck believed that simple organisms probably originate via spontaneous generation, but they would subsequently transform into other forms via an innate propensity towards increased complexity and/or adaptations to local conditions.

    Cuvier was strongly opposed to the idea of transformation, which was antithetical to his concept of the highly integrated functional machine. One of his more important answers to Lamarck's transformationism was a paper on the anatomy of the aquatic bird known as the ibis. Contrary to the arguments of transformists, Cuvier demonstrated that the skeleton of an ibis mummified by the ancient Egyptians was, in fact, identical to that of a modern species.

    Cuvier saved his harshest and most venomous attack on Lamarck with his official eulogy; as Stephen J. Gould has commented, Cuvier did not believe in the maxim "say only good about the dead." Cuvier, a devoted empiricist, rightly lambasted Lamarck for his speculative, grand systems. But he also grossly mischaracterized Lamarck's idea of adaptations as an expression of organic will: "It is the desire and the attempt to swim that produces membranes on the feet of aquatic birds." Cuvier concluded that "A system established on such foundations may amuse the imagination of a poet;" but that such couldn't be tolerated by true scientists. (See Gould (2002), pages 171-172.) [go back]
  • Cuvier's "correlation of parts" was central to his methods in comparative anatomy and vertebrate paleontology. He envisioned an animal as an integrated and functional machine. In Discours preliminair , Cuvier presents examples of tight functional and anatomical integration for carnivores and ungulates. For his example of functional morphology of a carnivore skull he states:

    ". . . for the jaw to be able to seize [the prey], it must have a certain form of condyle; a certain relation between the position of the resistance and the [muscular] power with the point of support; a certain volume in the temporal muscles, which demand a certain size to the fossa that accommodates them, and a certain convexity to the zygomatic arch under which they pass; and that zygomatic arch must also have a certain strength to give support to the masseter muscle."

    He then compares the functional morphology of an ungulate (hoofed mammal) with that of the carnivore:

    "For example, we see clearly that hoofed animals must all be herbivores, since they have no means of seizing prey. We also see that, as their forefeet have no other use than to support the body, they do not need such a robustly organized shoulder [as a carnivore], from which results the absence of the clavicle and acromion, and the narrowness of the shoulder blade."

    Cuvier presented this concept of functional integration in almost mathematical terms and he argued that the whole animal could theoretically be known from a fragment. Although Cuvier believed that there were "rational" causes for the correlation of parts, he conceded: "when theory fails observation must provide." In other words, one can induce the identity or affinity of a fossil animal because the anatomy of its fragment is similar to the corresponding fragments of known animals. For example, if it has a tooth like the distinctive molars of elephants, it must be some kind of elephant.

    Cuvier's "correlation of parts" was based on the analysis of modern mammals belonging to well-defined lineages (e.g., carnivores, deer, and bovids). As such, his theory could pose problems dealing with species that exhibit intermediate or unusual characters. It compelled him to identify the skull of a chalicothere (large odd-toed ungulates with claws, e.g., Moropus) as that of a horse while its feet were assigned to a sloth. Had he not known that the mastodon had tusks and a body similar to an elephant, he would have been hard pressed to determine the affinity of its distinctive teeth. Nonetheless, his "correlations" spurred advances in the study of functional morphology and serves as a conceptual framework with which to evaluate morphological characters. In addition, his ability to induce the identity and affinity of fossil species via comparative anatomy was unsurpassed by his contemporaries. [go back]
  • Cuvier also incorporated contemporary and historical observations of erosion and sedimentation into his estimation of the date for his most recent revolution. For example, the Roman city of Ravenna was once a port on the Adriatic but it now lies about 75 miles inland because of the coastal sedimentation. To him, the surficial deposits, which contain the remains of mammoths, mastodons and other extinct giants, could easily have accumulated within a few thousand years. [go back]
  • Scala Naturae, also known as the "Chain of Being," is the idea that life is arranged in an ideal, linear progression from the simplest atom to the most complex and perfect beings (i.e., humans). The progression of Scala Naturae was continuous (i.e., no chain was broken). For instance, fungi were thought to be intermediate between stones and "simple" plants, while polyps (e.g., Hydra ) were intermediate between "advanced" plants and Vermes (worms). This idea, which has roots in Ancient Greece, was embraced by Christian theologians and Enlightenment Diests (including Thomas Jefferson).

    However, Scala Naturae became less and less tenable as more was learned about the natural world. By the end of the 18th century, several prominent naturalists, including Blumenbach and Lamarck began to question the unbroken nature of its progression and several botanists found no discernible progression among plants. Nonetheless, Scala Naturae proved persistently popular among zoologists until it was convincingly discredited by Cuvier.

    His examination of the internal anatomy of a wide range of animals led Cuvier to conclude that there were four discrete embranchments (branches or phyla) of animal life: Vertebrata (i.e., vertebrates), Mollusca (e.g., snails, clams, squid), Articulata (e.g., segmented worms, insects, crustaceans), and Radiata (e.g., corals, polyps, sea stars). According to Cuvier, each embranchment was characterized by key morphological characters not shared with members of any of the other embranchments. In other words, there was a morphological chasm between any two of these embranchments. There were no intermediates and no linear progression. [go back]
  • Samuel Morton and Richard Harlan were the two most important American paleontologists during the 1820-1840s. Both were influenced by Cuvier, but Harlan was particularly forceful in advocating Cuverian methods and theories. See The Philadelphia School of Paleontology for more information. [go back]