Geoffroy Saint-Hilaire, Éitienne

Born Apr. 15, 1772, in fitampes, France, and died June 19, 1844, in Paris. French zoologist and evolutionist; a precursor of C. Darwin. Member of the French Academy of Sciences (1807).

In 1793, Geoffroy Saint-Hilaire occupied the chair of vertebrate zoology in the National Museum of Natural His-tory. From 1798 to 1801 he took part in an expedition to Egypt, where he collected animals of outstanding scientific importance (17 new genera and species of mammals, 25 genera and species of reptiles and amphibians, and 57 genera and species of fish, including the relict fish Polypterus).

The joint works of G. Cuvier and Geoffroy Saint-Hilaire led to a reform of the classification of vertebrate animals on the basis of comparative anatomical features. Relying on comparative anatomical evidence of the structural unity of organisms within individual classes of vertebrates, Geoffroy Saint-Hilaire tried to find the morphological unity of animals of different classes; in this, he used the method of comparing embryos that subsequently became the basis of the embryological proof of evolution and the law of biogenesis. To substantiate his theory of the unity of the structural plan of animals, Geoffroy Saint-Hilaire in his Philosophy of Anatomy used what he called synthetic morphology, which rests on the “theory of analogs” and on the principles of relationships, affinity, and equilibrium of organisms. How-ever, in his effort to broaden as much as possible his theory concerning the unity of the structural plan, he made a number of serious mistakes. (He admitted, for example, a correlation between the external chitinous skeleton of arthropods and the internal bony skeleton of vertebrates.)

Geoffroy Saint-Hilaire’s theory of a single plan governing the organization of all the phyla of the animal world (disregarding qualitative differences) was metaphysical, but it helped to confirm the idea of unity of origin and was therefore subjected to harsh criticism from scientists who argued in favor of the invariability of the species. A debate was held in the Paris Academy of Sciences in 1830 between Geoffroy Saint-Hilaire and Cuvier, who denied the existence of relationships and transitions in the organization of animals of different phyla. Cuvier criticized Geoffroy Saint-Hilaire for causalism (causal interpretation of phenomena) and pantheism, that is, essentially atheism. In defending his theory of the unity of the animal world, Geoffroy Saint-Hilaire sharply criticized both Cuvier’s theory of four isolated types of animal structure lacking common features of organization and transitions and his teleological principle of “ultimate causes.”

The formal victor in the debate was Cuvier, who disclosed several factual errors made by Geoffroy Saint-Hilaire, but the latter’s progressive idea concerning the unity of the animal world, which was the basis of the theory of evolution of organic nature, was supported by many leading thinkers and scientists, such as the Swiss A. De Candolle, the German J. Goethe, and the Russians A. I. Herzen, V. G. Belinskii, K. F. Rul’e, N. A. Severtsov, and K. A. Timiriazev.

In 1831, Geoffroy Saint-Hilaire, despite the severe criticism of reactionary circles, came forward with a direct defense of the idea of evolution. To back up his views, he cited extensive data from a variety of biological sciences (embryology, paleontology, comparative anatomy, and taxonomy). Geoffroy Saint-Hilaire advanced the concept of monstrosities as natural phenomena (Philosophy of Anatomy, vol. 2, 1822). He laid the foundation of experimental teratology; he obtained several artificial monstrosities in experiments on chicken embryos. He created the science of domestication of animals that was developed by his son Isidore Geoffroy Saint-Hilaire.