Geoffroy Saint-Hilaire: A Visionary Naturalist

  • Hervé Le Guyader
, transl. Marjorie Grene University of Chicago Press: 2004. 302 pp. $45, £31.50 0226470911 | ISBN: 0-226-47091-1
Credit: CHRISTIAN DARKIN

In evolutionary terms, the most remarkable discoveries of developmental biology in the 1980s and 1990s were that the molecular mechanisms of anteroposterior axis formation are shared across most of the animal kingdom, and that vertebrates form a dorsoventral axis in a similar way to insects, only upside-down. This axial inversion had a special appeal because it seemed to confirm an old and much-derided view. Its first proponent was the French zoologist Étienne Geoffroy Saint-Hilaire, subject of this book by Hervé Le Guyader.

In 1830, Geoffroy faced his one-time friend and long-term colleague Georges Cuvier at the Muséum d'Histoire Naturelle in Paris, in one of the most famous controversies in the history of science. Cuvier, the most powerful comparative anatomist of the age, had divided the animal kingdom into four completely separate branches: vertebrates, articulates (largely arthropods and annelids), molluscs and radiates (echinoderms, cnidarians and various other groups). Even within these divisions, he allowed structural similarity to result solely from the same functional demands.

Geoffroy, by contrast, taught that function did not really matter, nor even form; what counted were the connections between the parts. He founded a ‘philosophical’ anatomy on ‘analogy’ (homology, to us), and pushed the idea that all animals are built to a single plan. Having established a common scheme for vertebrates, in 1820 he extended it to the articulates. Insects, he pronounced, are vertebrates that live within their vertebral columns and walk on their ribs.

Cuvier restrained himself until a decade later, when Geoffroy exploited two young naturalists' suggestion that cuttlefish, representing molluscs, were like vertebrates doubled back on themselves. The simmering dispute now boiled over into a confrontation on the floor of the Academy of Sciences in Paris that captivated the learned world and newspaper-reading public alike.

As Toby Appel showed in The Cuvier– Geoffroy Debate (Oxford University Press, 1987), much more than cephalopod anatomy was at stake. Cuvier's functionalism opposed Geoffroy's morphology. The austere, logical Protestant fought the intuitive, impetuous, romantic Deist. Cuvier's fact-driven, establishment science was pitted against Geoffroy's broad speculation and alliances with progressive forces beyond the academy. Cuvier is usually said to have won, and on the narrow issue he did, but Geoffroy's philosophical anatomy was more influential than used to be thought. For leading naturalists in the next generations, both positions seemed too extreme. In finding a resolution, homology was made into evidence of darwinian evolution — and some darwinists argued that the vertebrates originated from annelids by inversion of the dorsoventral axis.

Le Guyader's book, first published in French six years ago, offers a judicious selection of Geoffroy's works, each with a short introduction. These texts have never been translated before because nineteenth-century British naturalists read them in French, and because by the middle of the century Geoffroy had been marginalized. We have the preliminary discourses to both volumes of his Anatomical Philosophy; the first of three treatises on the organization of insects, which deals with the anteroposterior axes of insects and vertebrates; the recently much-cited review, “General considerations on the vertebra”, with its reflections on dorsoventral organization and the figure of the inside-out and upside-down lobster; and the whole of the Principles of Zoological Philosophy, Geoffroy's record of the 1830 debate.

Anglophone biologists and historians of science will be glad to have these scarce and important works so readily available. Some additional editorial work might, though, have produced more scholarly and user-friendly texts. Martin Rudwick's translations in Georges Cuvier, Fossil Bones and Geological Catastrophes, published by the University of Chicago Press in 1997, show the advantages of identifying authors mentioned, giving full references for cited works, explaining allusions and discussing tricky points. But if the English prose here rarely sparkles, Geoffroy is largely to blame. On style, Cuvier won hands down.

So why should we read these works today? The Cuvier–Geoffroy debate has been given many different meanings, by the two sides at the time and by commentators since. For Le Guyader, molecular developmental biology allows us to recognize Geoffroy as a “visionary of genius” who — Le Guyader realizes it would be grossly anachronistic to call him right — was “right to be wrong”. A paper from 1822 certainly generates additional interest now that it is cited again. But the deeper reasons why Geoffroy still matters are the approaches that he and Cuvier framed and fought over, rather than any specific answers he gave. Their views decisively shaped our science.