The development of Darwin's theory : natural history, natural theology, and natural selection, 1838-1859 / Dov Ospovat.

  • Ospovat, Dov.
Date:
1995, ©1981
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: The development of Darwin's theory : natural history, natural theology, and natural selection, 1838-1859 / Dov Ospovat. Source: Wellcome Collection.

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    The development of Darwin's theory Darwinian as the theory of natural selection. It is a useful corrective to recall that such opponents of transmutation as Prichard and Agassiz used these same arguments to reach the same conclusion - that the principle of adaptation could not explain geographical distribution.'^ The explanation of organic structure offered by Cuvier and the natural theologians was also unacceptable to Darwin, for it suffered from the same defects as teleological explanations of geographical and geological distribution. Adaptation might well explain some structures, but it could not explain them all. It could not explain, for instance, vestigial or rudimentary organs which served no apparent purpose in their possessors; it could not explain the unity of type of such large groups as the vertebrates; and it could not explain the similarities between fossil and living inhabitants of the same country, except in those cases where external conditions had not changed. If, however, the principle of adaptation is supplemented by another principle, heredity, then such phenomena make sense. The condition of every animal, Darwin said, is partly due to direct adaptation and partly to hereditary taint; hence the resemblances and differences, for instance, of finches of Europe and America, etc. etc. etc.'® It appears that Darwin first became aware of the conflict between the proponents of the teleological and nonteleological approaches to problems of organic structure in 1837, when he read Geoffroy's account of his debate with Cuvier. Darwin was not convinced by Geoffroy's arguments for the unity of type of all animals (I deduce from extreme difíiculty of hypothesis of connecting mollusca and vertebrata, that there must be very great gaps). And he could not figure out what Geoffroy's views were on several important issues. But Darwin nevertheless saw that Geof¬ froy's ideas were more congenial to his own than were Cuvier's. He was so sure of this that he assumed, without it seems knowing it to be true, that Geoffroy believed in descent: does not say [animals] propagated, but must have concluded so. In Geoffroy's copious extracts from Cuvier's writings, on the other hand, Darwin noted only the inadequacies of Cuvier's explanations. Cuvier's notion that each animal is constructed with reference solely to its own needs, and not to any general type form, does not agree with old and modern types being constant, Darwin said. (Already in the opening pages of the first notebook he had written that propaga- 28