Alfred Russel Wallace - Founder of a Great Divide

Alfred Russel Wallace (1823 –1913) was a self-taught naturalist who is best known for developing a theory of evolutionary origin at about the same time Charles Darwin was putting the finishing touches on his theory of natural selection. Wallace's theory is now vastly overshadowed by Darwin's convincing dissertation on natural selection. But Wallace's thwarted theory represents only a small part of his many accomplishments.

Wallace explored the Malay Archipelago during the 1850s and 1860s. During that time, he observed a wide variety of wildlife and habitats. He collected and catalogued countless specimens for natural history museums. The observations he made, coupled with his curious nature, led him to ask probing questions about the natural world. Many of those questions focused on the geographical distribution of species: why were species found in certain locations but were absent from other apparantly suitable habitats? Today, such questions take refuge in their own field of scientific study: biogeography.

Wallace's observations of species distribution culminated in his identification of a division in the natural world: a line that bisects the Malay Archipelago between the islands of Borneo and Celebes. This line is now know as the Wallace Line. On the west side of the Wallace Line, organisms are of Asian descent. On the east side of the Wallace Line organisms are of Australian descent. You can read more about Alfred Russel Wallace and the Wallace Line in David Quammen's article for National Geographic, The Man Who Wasn't Darwin. There is also a terrific gallery of images that accompanies the article.