6.1: Georges Cuvier

Georges Cuvier

We admire the power by which the human mind has measured the motions of the celestial bodies, which nature seemed to have concealed forever from our view. Genius and science have burst the limits of space; and observations, explained by just reasoning, have unveiled the mechanism of the universe. Would it not also be glorious for man to burst the limits of time, and, by means of observations, to ascertain the history of this world, and the succession of events that preceded the birth of the human race?

And yet, Cuvier saw no evidence that one fossil form gradually changes into another. In looking at any given form, he saw long-term stability; in looking from one form to the next, he saw sharp morphological distinctions. When Lamarck proposed that the transmutation of one type into another is gradual, Cuvier claimed to see nothing in the fossil record contradicting the idea that the typical fossil form is static once it comes into existence. In response he wrote:

If the species have changed by degrees, we ought to find traces of these gradual modifications. Thus, between the palaeotheria and our present species, we should be able to discover some intermediate forms; and yet no such discovery has ever been made.^[1]

Cuvier, however, rarely speculated on the observations he reported. He seems to have been more interested in documenting the fact of evolution than in identifying the underlying biological forces that brought it about. His attitude seems to have been the same as that of modern paleontologist Stephen Jay Gould, who once told the writer that saltational change had to be accepted with or without explanation since it is an empirical fact documented in the fossil record. However, I have long thought it unlikely that other scientists would accept the phenomenon of saltation in the absence of a clear genetic explanation. The supposition that new forms of life are typically produced by stabilization processes provides such an explanation.