Pattern and Progress on the Geological Stage 491
their primary query, both Cuvier and Lyell asked not whether, but rather how,
science should treat the empirics of the geological record—and Cuvier's chief
difference with Lyell and Darwin centered upon his empirical literalism versus
their commitment to probing behind the appearances of a systematically imperfect
record. A dramatic example of this distinction occurs at a key point in Cuvier's
Essay, and serves to illustrate the real and continuing contrast between legitimate
themes in catastrophism versus Darwin's need for a uniformitarian geology based
upon the accumulation of small effects. In Section 30 on "proofs that the extinct
species of quadrupeds are not varieties of the presently existing species," Cuvier
considers a potential argument against the reality of mass extinctions produced by
geological catastrophes. No one can deny that many fossil quadrupeds represent
species no longer living—for Cuvier had proved this point beyond a doubt. Only
one logical alternative therefore remained to challenge Cuvier's own conclusion
that these ancient species had perished—namely, evolution. Perhaps these forms
never died, but gradually changed into different species now extant. Lamarck,
Cuvier's closest colleague, had been advocating this idea for more than a decade,
and straining their former friendship thereby (see Chapter 3). But Cuvier replied
with an empirical rejoinder that could scarcely be gainsaid so long as the fossil
record could be treated as literally accurate. No intermediary forms have been
found as fossils, while new species occur in strata directly atop the doomed faunas:
This objection may appear strong to those who believe in the indefinite
possibility of change of forms in organized bodies, and think that during a
succession of ages, and by alterations of habitudes, all the species may
change into each other, or one of them give birth to all the rest. Yet to these
persons the following answer may be given from their own system: If the
species have changed by degrees, as they assume, we ought to find traces of
this gradual modification. Thus, between the Palaeotherium and the species
of our own days, we should be able to discover some intermediate forms;
and yet no such discovery has ever been made. Since the bowels of the
earth have not preserved monuments of this strange genealogy, we have a
right to conclude, That the ancient and now extinct species were as
permanent in their forms and characters as those which exist at present; or
at least, that the catastrophe which destroyed them did not leave sufficient
time for the production of the changes that are alleged to have taken place
(1818, p. 119).Darwin, as we all know, did not challenge Cuvier's literal description, but
argued that a woefully imperfect record had failed to preserve insensibly graded
intermediates in almost all cases. And Darwin, with his characteristic honesty, also
admitted that his entire system depended upon the validity of this approach to the
fossil record: "He who rejects these views on the nature of the geological record,
will rightly reject my whole theory" (1859, p. 342).
In another confessional paragraph in the same mode, Darwin wrote of his debt
to Lyell: "He who can read Sir Charles Lyell’s grand work on the Principies of