miércoles, 4 de marzo de 2009


Charles Darwin, the British naturalist who lived between the years 1809 and 1882. His work "On the Origin of Species by Natural Selection or the Preservation of Favored Races in the Struggle for existence" published on November 24, 1859, has revolutionized the concepts of time and opened a field of controversial discussion. His thought influenced by the text of Malthus' First Essay on Population "(1798) and the Scottish Charles Lyell's" Principles of Geology "(1830) emerged after observing the flora and fauna of the Galapagos archipelago, a trip made on the ship "Beagle," tour that lasted five years, between December 27, 1831 and October 2, 1836. Darwin observed on this trip, birds called finches, which found seven different species, but with a common trunk, which were separated in adapting to different environments. Charles Lyell, enrolled in the current, had argued that it should not be resorting to evolution in terms of catastrophic events such as floods, but the same causes that have acted over long time periods. Darwin, in his book, although his ideas had already been made a year earlier in two communications to the Linnean Society of London, tells us that in every generation gaps are inherited without apparent explanation, that make the organisms evolve by natural selection . Species with greater adaptation to the environment are those that are increasing, while the rest is heading towards its demise, which would mean a rate of survival. It is proved by fossil remains, many ancient species have become extinct, and others were taking on new forms. For about four billion years ago came the first signs of life through rudimentary cells. Is about seven hundred million years of multicellular organisms appeared. Invertebrates were nearly six hundred million years and the fish, early vertebrates, they did 450 million years ago. Flora originated a hundred and fifty million years. Thus, the fish were adapted to aquatic life, terrestrial animals to life in that environment, as did the flying. But the atmosphere changed, and these living things must adapt to these changes. Limited resources and competition led to the survival of the fittest. There are no two identical individuals. Differences arise between groups, sometimes for reasons of geography, because the particularities of the medium do take certain peculiarities, and sometimes there are as many differences between the two, which makes it impossible including reproduction. At this point, now we talk about different species.

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