Editing Georges Cuvier (section)

=== Principle of the correlation of parts ===
In a 1798 paper on the fossil remains of an animal found in some plaster quarries near Paris, Cuvier states what is known as the principle of the correlation of parts. He writes:<ref name=":0">{{harvnb|Rudwick|1997|p=36}}</ref>

:''If an animal's teeth are such as they must be, in order for it to nourish itself with flesh, we can be sure without further examination that the whole system of its digestive organs is appropriate for that kind of food, and that its whole skeleton and locomotive organs, and even its sense organs, are arranged in such a way as to make it skilful at pursuing and catching its prey. For these relations are the necessary conditions of existence of the animal; if things were not so, it would not be able to subsist.''

This idea is referred to as Cuvier's principle of correlation of parts, which states that all organs in an animal's body are deeply interdependent. Species' existence relies on the way in which these organs interact. For example, a species whose digestive tract is best suited to digesting flesh but whose body is best suited to foraging for plants cannot survive. Thus in all species, the functional significance of each body part must be correlated to the others, or else the species cannot sustain itself.<ref name=":1">{{Cite book|title=The Meaning of Fossils: Episodes in the History of Palaeontology|last=Rudwick|first=Martin|publisher=Elsevier Publishing Company, Inc.|year=1972|isbn=0444-19576-9|location=New York, NY|pages=104–115}}</ref>

==== Applications ====
Cuvier believed that the power of his principle came in part from its ability to aid in the reconstruction of fossils. In most cases, fossils of quadrupeds were not found as complete, assembled skeletons, but rather as scattered pieces that needed to be put together by anatomists. To make matters worse, deposits often contained the fossilized remains of several species of animals mixed together. Anatomists reassembling these skeletons ran the risk of combining remains of different species, producing imaginary composite species. However, by examining the functional purpose of each bone and applying the principle of correlation of parts, Cuvier believed that this problem could be avoided.

This principle's ability to aid in the reconstruction of fossils was also helpful to Cuvier's work in providing evidence in favour of extinction. The strongest evidence Cuvier could provide in favour of extinction would be to prove that the fossilized remains of an animal belonged to a species that no longer existed. By applying Cuvier's principle of correlation of parts, it would be easier to verify that a fossilized skeleton had been authentically reconstructed, thus validating any observations drawn from comparing it to skeletons of existing species.

In addition to helping anatomists reconstruct fossilized remains, Cuvier believed that his principle also held enormous predictive power. For example, when he discovered a fossil that resembled a marsupial in the gypsum quarries of Montmartre, he correctly predicted that the fossil would contain bones commonly found in marsupials in its pelvis as well.<ref name=":1" />

==== Impact ====
[[File:Georges-Léopold-Chrétien-Frédéric-Dagobert, Baron Cuvier. Li Wellcome V0001428.jpg|thumb|upright|Line engraving of Cuvier, 1832]]
Cuvier hoped that his principles of anatomy would provide the law-based framework that would elevate natural history to the truly scientific level occupied by physics and chemistry thanks to the laws established by Isaac Newton (1643 – 1727) and Antoine Lavoisier (1743 – 1794), respectively. He expressed confidence in the introduction to ''[[Le Règne Animal]]'' that someday anatomy would be expressed as laws as simple, mathematical, and predictive as Newton's laws of physics, and he viewed his principle as an important step in that direction.<ref>{{cite book|title=Cuvier's animal kingdom : arranged according to its organization|url=https://archive.org/details/cuviersanimalkin00cuviiala|last1=Cuvier|first1=Georges|last2=McMurtrie|first2=Henry|year=1834|pages=1–4|publisher=Orr and Smith|doi=10.5962/bhl.title.28915|hdl = 2027/ncs1.ark:/13960/t9280ss6c}}</ref> To him, the predictive capabilities of his principles demonstrated in his prediction of the existence of marsupial pelvic bones in the gypsum quarries of Montmartre demonstrated that these goals were not only in reach, but imminent.<ref>{{Cite book|title=Georges Cuvier, fossil bones, and geological catastrophes : new translations & interpretations of the primary texts|last=S.|first=Rudwick, M. J.|date=1998|publisher=University of Chicago Press|isbn=978-0226731063|edition=[Pbk. ed., 1998]|location=Chicago, Ill.|pages=69–73|oclc=45730036}}</ref>

The principle of correlation of parts was also Cuvier's way of understanding function in a non-evolutionary context, without invoking a divine creator.<ref>See discussion in {{harvnb|Reiss|2009}}</ref> In the same 1798 paper on the fossil remains of an animal found in plaster quarries near Paris, Cuvier emphasizes the predictive power of his principle, writing,<ref name=":0" />

<blockquote>Today comparative anatomy has reached such a point of perfection that, after inspecting a single bone, one can often determine the class, and sometimes even the genus of the animal to which it belonged, above all if that bone belonged to the head or the limbs ... This is because the number, direction, and shape of the bones that compose each part of an animal's body are always in a necessary relation to all the other parts, in such a way that—up to a point—one can infer the whole from any one of them and vice versa.</blockquote>

Though Cuvier believed that his principle's major contribution was that it was a rational, mathematical way to reconstruct fossils and make predictions, in reality, it was difficult for Cuvier to use his principle. The functional significance of many body parts was still unknown at the time, and so relating those body parts to other body parts using Cuvier's principle was impossible. Though Cuvier was able to make accurate predictions about fossil finds, in practice, the accuracy of his predictions came not from application of his principle, but rather from his vast knowledge of comparative anatomy. However, despite Cuvier's exaggerations of the power of his principle, the basic concept is central to comparative anatomy and paleontology.<ref name=":1" />