Alfred Russel Wallace (1823 - 1913) was a British naturalist, and co-discoverer of the principle of evolution by natural selection. Wallace travelled to South America with Henry Bates (see 'Batesian mimicry') and then to the Malay archipelago. Like Darwin, he was struck by the variation of species on different islands, and in 1858 he read Malthus's Essay on the Principle of Population . Together, Wallace and Darwin presented their ideas to the public, although the theory soon became known as Darwinism.

Wallace was a spiritualist, and doubted that natural selection could be applied to humans. He was particularly interested in biogeography, and carefully systematized the geographic distributions of animals.

This photograph of Alfred Wallace was taken in 1848.