Darwin, Charles

Darwin

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Charles Darwin was born on 12th February 1809. In spite of coming from a distinguished family (his grandfather Erasmus Darwin had been an eminent physician and naturalist and he was related also to both the Wedgwood and Galton families), he did not shine either at school or at the Universities of Edinburgh and Cambridge where he subsequently studied. His passion, even before he went to school was collecting. '...I collected all sorts of things, shells, seals, franks and minerals. ..'. It is interesting that later Darwin was particularly proud of his study of the barnacles Cirripedia on which he worked for eight years, eventually publishing two thick volumes describing all the known living species. After considering and rejecting his father's suggestions of careers in medicine or the Church, Darwin made the journey that was to provide the basis for his later work. For five years he travelled as an unpaid naturalist on board HMS Beagle on a survey expedition to South America and the Pacific. Darwin's job was to make detailed observations, often based on long excursions inland, of geological formations, flora and fauna, and of the customs and ways of life of the inhabitants he encountered. A contemporary review described the journal that Darwin later published (1842) of his findings as re cording 'the observations of a mind singularly candid and unprejudiced – fixing upon nature a gaze, keen, penetrating, reflective and almost reverent'. The most significant phase of Darwin's voyage came when the Beagle sailed out along the Equator 600 miles west of the coast of Ecuador for a four week visit to the Galapagos Archipelago. Here Darwin was overwhelmed by the number of species of birds, shells, insects and animals he had never before encountered. He recorded 26 species of land birds, only one of which had been seen elsewhere. His observations on these islands were a key factor in stirring doubt in his mind, undermining the prevailing view of the time that species were fixed and immutable as they had been from the moment of creation. He noted that the varied species about him often shared many characteristics in common and differed only by gradations. Among the land birds he discovered there were 13 different kinds of finch. In his journal he wrote: 'Seeing this gradation and diversity of structure in one small intimately related group of birds, one might really fancy that, from an original paucity of birds in the Archipelago, one species had been taken and modified for different ends!' He noted also that each of the closely related species of plants and animals tended to be identified with one island in particular; 'different islands to a considerable extent are inhabited by a different set of beings'. Darwin concluded, 'one is astonished at the amount of creative force, if such an expression may be used, displayed on these small barren rocky islands, and still more so at its diverse yet analogous action on points so near each other'. Later, after his return to England, Darwin reasoned that the slightly altered characteristics of the various species of Galapagos finch had evolved due to a particular kind of survival advantage conferred by a chance heredital variation. He noted how the beaks of some finches were appropriate for feeding on insects, those of other species for feeding on seeds. Given time and aided by separation on different islands, such chance differences had led to the evolution of different species of finch, each with its own characteristic habits and each filling its own individual 'ecological niche'. Observations like these made on his round the world voyage, and the reasoning stimulated by them were to be eventually drawn on heavily for the theory of evolution postulated in On the Origin of Species. At the age of 27, Darwin arrived home after his five year voyage around the World. From then till hi s death in 1882 at the age of 73, Darwin was no longer to lead a life of action but one of meditation and the development of ideas. With the help of leading specialists from different disciplines, his huge collection of shells, rocks, insects, animals and fossils was sorted out, described and prepared for publication. In July 1837 he also began the first of a series of notebooks in which he jotted down observations, thoughts and reasoning directed towards the problem of the origins and 'transmutation' of species. Soon he had developed the position that species were not fixed at creation but gradually evolved from common ancestors, and was exploring possible processes through which this evolutionary change could have come about. He observed among other things, the importance of sexual reproduction for creating variation so that environment could act as a selective force, and of isolation and separation as a way of maintaining and increasing differentiation between species. Darwin continued to build up evidence for his evolution theory but it was not until 1858 when it bec ame clear that another naturalist Alfred Wallace had come up with similar ideas that he eventually got down to finishing it. On the Origin of Species was reviewed rapturously by T. H. Huxley in The Times. Other enthusiastic supporters included Karl Marx who later requested that he be allowed to dedicate the English translation of Das Kapital to Darwin (Darwin refused). Many people, however, reacted negatively, even with horror, particularly those who felt that the theory contradicted the Biblical account of the fixed creation of each species (which, of course if did). The ensuing controversy culminated in a stormy debate at Oxford where the eloquent Bishop Wilberforce who had vowed to 'smash Darwin', was routed by Darwin's 'bulldog', his ardent supporter Huxley. Admiral Fitzroy the former Captain of the Beagle was there and very much on Wilberforce's side angri ly decrying Darwin as a 'viper' he had unhappily embraced. Subsequently Darwin published The expression of the Emotions in Man and Animals (1872) and The Descent of Man, and Selection in Relation to Sex (1874) in both of which he attempted to apply his theory more directly to human behaviours. In On the Origin of Species Darwin notes the great variability of all living things, observing varia tion occurring both in nature and as a result of selective, domestic breeding. Secondly, he notes the very high rate at which organisms tend to reproduce. However, he also observes that the number of individuals in a population of species tends, on the whole, to remain relatively constant over a long period of time. From these propositions he deduces that many must die. Those that will die and not reproduce will be those that are least effectively adapted to environmen tal conditions. He therefore further deduces that subsequent generations will include individuals that not only maintain but may also improve on the adaptation of the parents. The varied evidence Darwin arrayed in support of his thesis included consideration of the fossil rem ains available at the time, the geographical distribution of plants and animals and the physiological and anatomical structures of living species, particularly in their embryonic forms. The improvement that might occur would be due to further variation resulting from the mixture of inheritance from two parents and from what Darwin considered to be chance changes which we would now call mutations. Thus, by gradual change, new species may evolve, each displaying subtle and highly effective adaptation to their natural habitats. In its fundamental principles, Darwin's theory is still accepted today, more than 130 years after it s original publication. Innumerable subsequent observations have confirmed and fleshed out his ideas and shown (as in the case of genetics) the detail of the processes on which they depend.

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