Alfred Russel Wallace, (8 January 1823 – 7 November 1913) was a British naturalist, explorer, geographer, anthropologist and biologist. He is best known for independently proposing a theory of evolution due to natural selection that prompted Charles Darwin to publish his own theory. He was considered the 19th century’s leading expert on the geographical distribution of animal species and is sometimes called the “father of biogeography”.
Wallace was one of the leading evolutionary thinkers of the 19th century and made a number of other contributions to the development of evolutionary theory besides being co-discoverer of natural selection. These included the concept of warning coloration in animals, and the Wallace effect, a hypothesis on how natural selection could contribute to speciation by encouraging the development of barriers against hybridization. Unlike Darwin, Wallace began his career as a travelling naturalist already believing in the transmutation of species.
The concept had been advocated by Jean-Baptiste Lamarck, Geoffrey Saint-Hillarie, Erasmus Darwin, and Robert Grant, among others. It was widely discussed, but not generally accepted by leading naturalists, and was considered to have radical, even revolutionary connotations. Prominent anatomists and geologists such as Georges Cuvier, Richard Owen, Adam Sedgwick, and Charles Lyell attacked it vigorously. It has been suggested that Wallace accepted the idea of the transmutation of species in part because he was always inclined to favor radical ideas in politics, religion and science, and because he was unusually open to marginal, even fringe, ideas in science.
He was also profoundly influenced by Robert Chambers’ work Vestiges of the Natural History of Creation, a highly controversial work of popular science published anonymously in 1844 that advocated an evolutionary origin for the solar system, the earth, and living things.