Biological evolution

In biology, evolution is the transformation of living species as manifested by changes in their genetic traits over generations. These successive changes may result from a single species, the formation of new "girls-species". The phenomenon of evolution can explain the origin of biodiversity on Earth. The history of the species can thus be thought of and represented as a tree phylogenetic

Some ancient philosophers (Lucretius, 98-54 BC, in particular) have approached the phenomenon of evolution, but it was not until the nineteenth century that theories offer scientific explanations, c ' is to say refutable or demonstrable. The model of transformation of Lamarck led the way. Then, from 1859 with the publication of On the Origin of Species by Charles Darwin, the Darwinian model of evolution has gradually established in the scientific community as one explaining maximum observable facts with minimal assumptions ( parsimony principle). Darwin illustrated with detailed observations the thesis that living species are not fixed categories but diversified over time, even disparaissent. As because of changes that occur gradually in a population he proposed the idea of natural selection, natural and spontaneous equivalent of artificial selection practiced by the pet breeders. Species are deeply conditioned by their natural environment, now called ecosystem. However, Charles Darwin, contrary to a widespread belief even in college, did not reject the Lamarckian mechanisms of habituation and transmission of acquired characteristics; there just added spontaneous variations and natural selection. This is only a year after Darwin's death in 1883 that August Weismann proved the separation of germ and somatic lineages and the impossibility of the transmission of acquired characteristics. There remained, in Darwin's work more than the variation-selection mechanism as probable.

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