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, interact: subsidence and coral growth, barriers and dispersal, variation and fitness. All three are based on abstract models which have numerous implications and can readily be tested. There is clear-cut series of rational operations leading to each theory, although natural selection differs in having an added difficulty of shifting from groups to populations. The development of thought from invasions to evolution, and from artificial selection and extinctions to natural selection, accompanied
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A588
Book:
Armstrong, Patrick. 1991. Under the blue vault of heaven: A study of Charles Darwin's sojourn in the Cocos (Keeling) Islands. Nedlands: Indian Ocean Centre for Peace Studies.
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, nevertheless to a remarkable extent influenced the way in which he collected material, and organised it in his mind. Moreover, he quite frequently attempted a crude analysis of situations in terms of the metaphors of stuggle and warfare that were later to dominate his thinking on evolution. It must also be stressed here, that in these early stages of the journey, as later on the trek that led to On the Origin of Species, Charles Lyell was his constant companion. Aboard HMS Beagle the association
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A588
Book:
Armstrong, Patrick. 1991. Under the blue vault of heaven: A study of Charles Darwin's sojourn in the Cocos (Keeling) Islands. Nedlands: Indian Ocean Centre for Peace Studies.
Text
PDF
A refuge for the destitute It may be said that the concept of long-distance dispersal is the natural companion of the theory of evolution. If all living plants and animals are derived from a few simple forms instead of being independently created, living things must have dispersed throughout the world. The plants and animals now found upon remote islands must at some time made the journey thither. In his later years Charles Darwin spent a great deal of time and energy investigating the means
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A588
Book:
Armstrong, Patrick. 1991. Under the blue vault of heaven: A study of Charles Darwin's sojourn in the Cocos (Keeling) Islands. Nedlands: Indian Ocean Centre for Peace Studies.
Text
PDF
Chapter 7 Concluding summary It has often been emphasised that there were significant connections between Darwin's various intellectual enterprises. It is perhaps just coincidence that The Structure and Distribution of Coral Reefs appeared in the same year that Darwin's first essay on evolution, the Sketch of 1842.1 Yet there are important links:- the experience on the Cocos (Keeling) Islands provided vital components for Darwin's first flirtation with the thought-form of gradualism; it
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1861, in G. Sarton, Darwin's Conception of the Theory of Natural Selection, Isis, XXVI (1937), 336-340. As Mayr has repeatedly pointed out, an essentialist approach to taxonomy was a major barrier to the discovery of evolution and natural selection. * E.g., Mayr, Introduction to Origin. To Agassiz, again, evolution was not possible, because categories of thought would have to be unchanging and eternal. Some forms of Platonism, however, are not opposed to evolution: for example, the French and
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Century: Evolution and the Men Who Discovered It (New York: Anchor, 1961), pp. 244-246, etc. But however true it may be that Darwin invoked other causes as explanatory factors in evolution, this does not of itself demonstrate that he did so to overcome the problems brought about by blending inheritance, or that he really gave up natural selection in the face of criticisms. On the contrary, the facts seem adequate to demonstrate that although Darwin considered blending a threat to his theory, he
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Darwin's biogeography may be interpreted as the consequence of his having applied the same methodology here as elsewhere. Thus, the biogeographic argument for evolution may be fruitfully compared with the first of Darwin's great syntheses, the theory of coral reefs. There are a number of formal similarities between the two theories. Both were discovered by reasoning from theoretical principles and by uniting disparate elements: subsidence and coral growth on the one hand, barriers and
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Relation to Sex, 2d. ed. (New York: D. Appleton, 1889). Essay C. Darwin and A. R. Wallace. Evolution by Natural Selection (Cambridge: University Press, 1958). Contains a foreword by G. de Beer, introduction by F. Darwin and Darwin and Wallace, Tendency of Species to Form Varieties. Expression C. Darwin. The Expression of the Emotions in Man and Animals (New York: Philosophical Library, 1955). Fertilization C. Darwin. The Effects of Cross and Self Fertilization in the Vegetable Kingdom (New York: D
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have originated in only some of them. * Cf. B. Patterson, Rates of Evolution in Taeniodonts, Genetics, Paleontology and Evolution, ed. G.L. Jepsen, G.G. Simpson, and E. Mayr (Princeton: University Press, 1949), pp. 243-278. Nor do we infer that the ancestral vertebrate had only tooth. On the same grounds, an originally hermaphroditic state in animals is not supported by the sexual homology, but is only consistent with it. It would seem that Darwin had another reason for considering the
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and bees, which leave no offspring to inherit the effects of experience and of modified habits. * Descent, pp. 67-68 [page 59 ]. Darwin devoted a large section in The Origin of Species to the evolution of complex behavior patterns among the neuter casts of social insects. * Origin, pp. 219-242 [pages 203-233 ]. An important motive was to refute inherited habit and Lamarckian mechanisms as sufficient to account for evolution. He writes: For no amount of exercise, or habit, or volition, in the
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evolutionary story consistent with the facts. Anomalies could be explained away by invoking vanished land-bridges or climatic changes. The result would be a picture of distributional changes using evolution to account for the observed relationships. But Darwin did nothing of the sort. For essentially the same reasons that he had embraced geological uniformitarianism, he insisted on interpreting distribution in terms of the present configuration of the continents: he realized that scientific
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mechanisms as Darwin did in fact obtain. * C. Epling and W. Catlin, The Relation of Taxonomic Method to an Explanation of Organic Evolution, Heredity, IV (1950), 313-325. Those who make such pronouncements habitually argue from the premise that they, personally, cannot see how it could be done. Their argument combines the modesty of Schopenhauer with the logic of Mary Baker Eddy; it does not follow from their own lack of imagination that Darwin or anyone else must fail. As in the rest of Darwin's
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dimorphism and brilliant coloration than Darwin believed. Many such attributes seem useful in allowing the recognition of other members of the same species, and this has such advantages as preventing the formation of sterile hybrids. * E. Mayr, Animal Species and Evolution (Cambridge: Harvard University Press, 1963), pp. 126-127; N. Tinbergen, The Origin and Evolution of Courtship and Threat Display, Evolution as a Process, ed. J. Huxley, A.C. Hardy, and E.B. Ford (London: George Allen and
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, Animal Species and Evolution. It is of no slight interest that this kind of argument resembles the ones Darwin used to test his coral reef hypothesis, and in his geographical verification of evolution. For strikingly similar reasons, it compels assent. Likewise, those who disagree with the conclusions do so because they do not understand the argument; the possibility of exceptions has never been an issue. Perhaps one reason why Darwin de-emphasized the importance of isolation in speciation was
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from social interaction. Conceiving of varieties or species as no more than abstract assemblages, founded on their similarities, precluded any such treatment. Nor could an understanding of evolution be obtained from a consideration of individual organisms apart from their relationships to the breeding community. Darwin attained his new conception of biological reality by a series of innovations, each of which brought him gradually nearer to his ultimate synthesis, and each of which was a
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that many of Darwin's theories, both geological and biological, arose in his mind because he read Lyell. * W. Coleman, Lyell and the 'Reality' of Species: 1830-1833, Isis, LIII (1962), 325-338. Darwin was an active supporter of uniformitarianism, and his publications were of great importance in showing the defects of catastrophic geology. * Cf. ibid.; W. F. Cannon, The Uniformitarian-catastrophist Debate, Isis, LI (1960), 38-55; J. W. Judd, The Coming of Evolution: The Story of a Great
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: Gustav Fischer, 1960), pp. 277-289. Yet one does well to bear in mind the fact that Darwin's contribution to geology was substantial, and that it alone would justify him an important place in the history of science. It is only by comparison to his work on evolution that Darwin's geology seems unimportant. CHAPTER II
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did not habitually reason in terms of comparative anatomy or evolution. It is characteristic of many great physiologists, such as Darwin and Harvey, that they can combine the comparative approach with the experimental. The idea giving evolutionary unity to The Power of Movement in Plants is that the generality of movements are derived from a precursor called circumnutation. Darwin shows, by a long series of controlled observations, that the growing parts of plants—root tips, young leaves, apices
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held in common by what had been called species, and partly owing to our understanding of the mechanisms of evolution, the biological species concept has increasingly prevailed. We now know that pre-evolutionary taxonomy was discovering a real order when it grouped organisms into species. A species is a population, a unit of evolution and of reproductive activity—a kind of social entity. It comprises all those biological individuals which exchange genetic material with one another, and which are
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evolution. We may see further parallels in the behavioral verification of mimicry and the application of the same test of selection, both artificial and sexual. Likewise, there is a distinct similarity between correlated growth and the principle of the direct action of the nervous system. Such close parallels are difficult to explain as owing to chance alone. And when one reflects upon how useful it is, in solving a scientific problem, to borrow models from other fields, one may readily apprehend
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