Darwinism

DARWINISM. - In D.'s work one must distinguish original scientific research from the speculative views that take their name from him. D. was certainly one of the most fertile and clearest naturalists of the nineteenth century, even if some of his hypotheses and interpretations, such as the one on the production of coral banks or on the circumnutation of climbing plants, have been abandoned. His research on fertilization in the plant kingdom (1858-77), which established the law of dichogamy, and on the importance of worms in the formation of humus, would suffice to preserve his fame. But on the problem of "species," which nevertheless occupied him constantly for 40 years, he did nothing that can be compared to the work of Mendel, Naudin or Jordan. In the history of biological philosophy and of the social sciences, however, "Darwinism" is important, by which one must properly understand the theory of the causes of the presumed transformation of living forms. D. started from the facts offered by the domestication of the breeds of animals that man has made domestic: how did the numerous breeds of pigeons, horses, oxen, dogs arise? The artificial "selection" (conscious or unconscious) of the breeder made them arise. Now, in nature there are species that vary, and the variability and heredity of the characters that appear in the varieties of species are perhaps effective for finding the factor that corresponds to the artificial selection of the breeder. D. postulated natural selection. The breeder's selection draws from species the most diverse and distant varieties; natural selection, having at its disposal a much longer time, succeeds in making forms cross the boundaries of the species, that is, in producing new species. In the struggle for existence individuals do not succumb by chance; the less fit succumb, the more fit survive; natural choice is a consequence of the struggle for existence among forms in continuous variation. Nature makes a choice of individuals that present and accentuate useful variations, and these modify themselves slowly, until they produce new species. Darwinism is therefore founded essentially on the analogy between natural (supposed) and artificial selection; natural selection accounts for the usefulness of the organs of adaptation. D. felt the paternity of this conception so strongly that, after 1859, he scarcely consented to "diminish the glory of selection" (letter to Hooker of 24 Nov. 1862) by recognizing the importance of the "direct action of physical conditions" (on living organisms) and then appealing to "sexual selection." But that pure Darwinism, that is, the efficacy of natural selection, is a simple interpretive hypothesis, D. himself conceded: "The belief in natural selection must at present be grounded entirely on general considerations. When we descend to details, we can prove that no one species has changed, i.e., we cannot prove that a single species has changed, nor can we prove that the supposed changes are beneficial, which is the groundwork of the theory" (letter to Bentham of 22 May 1863). In the last century at least one conclusion was clear, that with artificial selection one cannot succeed in obtaining a new species. Therefore, from the methodological point of view, Huxley was compelled to make the reservation: "I adopt D.'s hypothesis with the reservation that proofs be produced of the possibility of producing physiological species as a result of elective mating." The same experimental method dictated the rigorous criticism of Spencer, which, in the end, he summarized thus: "There is no inductive proof of natural selection. The facts that attest the effects of artificial selection are very numerous, but none appears to attest the effects of natural selection. Until the production of a single species by way of natural selection has been shown, there is not even the beginning of inductive proof." Then came the work of the geneticists, with Johansen at their head: the "pure breed" isolated by the work of artificial selection is fixed, oscillating for given characters only within certain limits beyond which it is not possible to go with small continuous and hereditary variations.

And then came other findings suggested to the evolutionists themselves by the development of certain series of fossil forms that they had to call "orthogenetic," such as to suggest the idea of an "evolution" directed from the very beginning in a determined sense, without that multitude of failed proofs, of inefficient, useless and unselected variations that the theory foresees and demands. According to Osborn, paleontology demonstrates that "in evolution law prevails over chance."

It is therefore understandable that some naturalists, evolutionists by principle and by philosophical prejudice, declare themselves anti-Darwinists and write that "Darwinism may very well have succeeded in making biologists themselves forget the obsessive problem of life" (Brien); see also EVOLUTION.

Luigi Scrimin