Charles Darwin, by contrast, found a lead for his theory of natural selection in the whimsical hobby of pigeon fancying, where the birds showed an enormous variety of form and behaviour.

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The theory of evolution by natural selection states the "fittest" animals or plants are more likely to survive and reproduce.

BBC: Alfred Russel Wallace statue at Natural History Museum

Wallace, who was born in Monmouthshire and also lived in Neath, was the co-discoverer of the theory of evolution by natural selection.

BBC: Alfred Russel Wallace's 19th Century letters go online

Scientist Alfred Russel Wallace, who proposed the theory of evolution by natural selection with Charles Darwin, corresponded with the great and good of 19th Century society.

BBC: Search for Alfred Russel Wallace's 19th Century letters

Letters written by scientist Alfred Russel Wallace, who proposed the theory of evolution by natural selection with Charles Darwin, will be published online for the first time.

BBC: Alfred Russel Wallace's 19th Century letters go online

These included well known naturalists such as Alfred Russel Wallace, who collected specimens in the Amazon and Malay Archipelago and independently formulated a theory of evolution by natural selection.

BBC: NEWS | Science/Nature | Darwin's letters archived on web

Darwin's theory - of random mutation followed by natural selection according to environmental suitability - changed science, changed the world.

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