Alfred Russel Wallace - British naturalist, explorer, geographer, anthropologist, and biologist

Alfred Russel Wallace OM, FRS (8 January 1823 – 7 November 1913) was an British naturalist, explorer, geographer, anthropologist, and biologist.
He did extensive fieldwork, first in the Amazon River basin and then in the Malay Archipelago, where he identified the Wallace Line dividing the fauna of Australia from that of Asia. He is best known for independently proposing a theory of natural selection which prompted Charles Darwin to publish on his own theory. Wallace was also one of the leading evolutionary thinkers of the 19th century who made a number of other contributions to the development of evolutionary theory, including the concept of warning colouration in animals, and the Wallace effect, a hypothesis on how natural selection could contribute to speciation by encouraging the development of barriers against hybridization. He was also considered the 19th century's leading expert on the geographical distribution of animal species and is sometimes called the "father of biogeography".


The Wallace Line
Bali is the physical end of what was once mainland Asia. Observing that a great contrast exists between the animal life of Bali and that of the islands to the east, Alfred Russel Wallace suggested that the treacherous, 24-km-wide strait separating Bali from the neighboring island of Lombok is an important divide, a biologically impassable line cleaving Asia from Australia. “In just two hours,” he suggested, “you can pass from one great division of the earth to the other, differing as essentially in their animal life as Europe does from America.”
During the last ice age, Wallace theorized, the sea level around the Greater Sundas fell enough to enable animals to travel overland from the Asian mainland, fanning out through the archipelago until they reached the deep trench of the Lombok Strait and could go no farther. While the Selat Bali (”Bali Strait”) separating Bali from Java has a maximum depth of 60 meters, the ocean depths between Bali and Lombok exceed 1,300 meters.

Wallace’s book, The Malay Archipelago, published in 1869 contemporary and parallel with Charles Darwin’s work, advanced a theory of evolution based on Wallace’s examination of the flora and fauna of the region. His imagined line dividing the Asian and Australian regions on either side of the Lombok Strait has since become known as the Wallace Line.

The differences between Bali and Lombok are obvious. Bali is lush, equatorial, smothered in the luxuriant vegetation of tropical Asia, while Lombok is wind-blown and dry like the Australian plains. Bali, Java, and islands west are characterized by the monkeys, squirrels, rabbits, tigers, elephants, bears, sheep, oxen, horses, orangutans, and pythons found in the dense tropical forests and jungles of Asia. On the islands east of Bali begin the parrots and other peculiar bird species, marsupials like wombats and kangaroos, the platypus, and giant lizards of the Australian region. Some “leakage” occurs, i.e., monkeys are found in Sumba.

Wallace was strongly attracted to unconventional ideas. His advocacy of Spiritualism and his belief in a non-material origin for the higher mental faculties of humans strained his relationship with the scientific establishment, especially with other early proponents of evolution. In addition to his scientific work he was a social activist who was critical of what he considered to be an unjust social and economic system in 19th-century Britain. His interest in biogeography resulted in his being one of the first prominent scientists to raise concerns over the environmental impact of human activity.

To celebrate the 150th anniversary of the joint reading of Alfred Russel Wallace and Charles Darwin’s papers on natural selection to the Linnean Society in London, the Natural History Museum exhibited a small but spine-tinglingly historic display of specimens and original documents relevant to the independent conception of the theory of natural selection by the two men:

Source: http://en.wikipedia.org/wiki/Alfred_Russel_Wallace, http://www.myzine.com/blog/141/alfred-russel-wallace-happy-birthday-evolution
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