Abstract
ON May 14, the Royal Society held a discussion on “The Present State of the Theory of Natural Selection”. Prof. D. M. S. Watson, opening the discussion, emphasised the lack of evidence that structural features are adaptive. In the brachiopod Rhynchonella, specimens with the inhalent and ex-halent apertures completely abnormal occur abundantly in a random collection of large numbers, of different sizes, from one locality: the abnormality has not been selected out. Much more experimental proof of a selective death-rate is needed. While a change may take place independently on parallel lines, the rate may differ; there is a compensatory principle as in the evolution of the horse, in which an advanced rate of change in the teeth is associated with a backwardness in the case of the feet. The same adaptive structure may arise independently in nearly allied animals, or the same ends may be served by different adaptations in other groups. Perisso-dactyls show a dental peculiarity, increasing the grinding surfaces, which artiodactyls never do; what it is that prevents them from doing so, is a clue to evolution. Such types of evolution, common to great groups, have nothing to do with the evolution of specific characters. Do ordinary species differ from each other by adaptive characters? Quantitative results are of the utmost importance, yet they are not forthcoming.
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The Present State of the Theory of Natural Selection. Nature 137, 876–877 (1936). https://doi.org/10.1038/137876a0
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DOI: https://doi.org/10.1038/137876a0