what did darwin propose as the mechanism of evolution?
""It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.""
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 Darwin theorized that species and breeds developed through the processes of natural selection and artificial selection or selective breeding . Genetic drift was embraced as an additional mechanism of evolutionary development in the modern synthesis of the theory . 

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 Darwin proposes sexual selection , driven by competition between males for mates , to explain sexually dimorphic features such as lion manes , deer antlers , peacock tails , bird songs , and the bright plumage of some male birds . He analysed sexual selection more fully in The Descent of Man , and Selection in Relation to Sex ( 1871 ) . Natural selection was expected to work very slowly in forming new species , but given the effectiveness of artificial selection , he could " see no limit to the amount of change , to the beauty and infinite complexity of the coadaptations between all organic beings , one with another and with their physical conditions of life , which may be effected in the long course of time by nature 's power of selection " . Using a tree diagram and calculations , he indicates the " divergence of character " from original species into new species and genera . He describes branches falling off as extinction occurred , while new branches formed in " the great Tree of life ... with its ever branching and beautiful ramifications " . 

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 Darwin 's theory of evolution is based on key facts and the inferences drawn from them , which biologist Ernst Mayr summarised as follows : 

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 Darwin published his theory of evolution with compelling evidence in his 1859 book On the Origin of Species , overcoming scientific rejection of earlier concepts of transmutation of species . By the 1870s , the scientific community and much of the general public had accepted evolution as a fact . However , many favoured competing explanations and it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed in which natural selection was the basic mechanism of evolution . In modified form , Darwin 's scientific discovery is the unifying theory of the life sciences , explaining the diversity of life . 

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 The most significant evolutionary theory before Darwin 's was that of Jean @-@ Baptiste Lamarck ; based on the inheritance of acquired characteristics ( an inheritance mechanism that was widely accepted until the 20th century ) , it described a chain of development stretching from the lowliest microbe to humans . The British naturalist Charles Darwin , combining the biogeographical approach of Humboldt , the uniformitarian geology of Lyell , Thomas Malthus 's writings on population growth , and his own morphological expertise , created a more successful evolutionary theory based on natural selection ; similar evidence led Alfred Russel Wallace to independently reach the same conclusions . 
