Cuvier was one of the principal adversaries against the theory of evolution. He was especially well known for his ability to reconstruct the overall anatomy of a fossil starting with mere fragments. This skill made it possible for him to become the first great specialist of the vanished species, such as prehistoric animals. He explains these disappearances with the theory of geological catastrophe proposed by certain geologists of his time.
It was his thesis that each animal has a coherent anatomy and no element of this architecture can be modified without deeply upsetting the general equilibrium. There would not have been any survival possible if things had come about as Lamarck and Saint-Hilaire claimed. This led Cuvier to propose a law of the necessary correlation of the parts. Darwin often used Cuvier’s law to demonstrate the opposite of what Cuvier wanted to prove. For Darwin, the need to maintain a minimum of general equilibrium can explain the maintenance of the parts of organs that had a precise function but that are then maintained uniquely to guarantee the equilibrium of the whole in the gravity field. It would be mostly these remnants, kept for architectural reasons, to which the emotions are related.
The discussion between Cuvier and Saint-Hilaire became one of the great popular debates of the 1820s. Cuvier represented a scientific vision compatible with the views of the aristocracy and the Catholic Church. Saint-Hilaire’s evolutionary vision was associated with the progressive forces that were about to take power in Western Europe. The following anecdote demonstrates to what extent this debate had become a major high-profile stake:87
Anecdote about Goethe at breakfast. The debates that were the rage concerning Cuvier and Saint-Hilaire were temporarily interrupted by the second French Revolution which erupted in July 1830. On the afternoon of the second of August, the elderly Goethe was reading the newspaper while eating breakfast. He asked his secretary, Johann Peter Eckermann, what he thought about the events in France: The volcano has come to an eruption, everything is in flames, and we have no longer a transaction with closed doors!â Eckermann thought that Goethe was referring to the upheaval in the streets and to the abdication of King Charles X. But in fact he was referring to the debate between Cuvier and Saint-Hilaire that was heating up now that the present government supported Saint-Hilaire. (Based on Eckermann, 1848, p. 290f)
The following sections are a tightly written theoretical summary of neo-Darwinian models. Some readers may prefer to read this material once they have a general vision of the content of this manual.