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In Darwin's Shadow: Alfred Russel Wallace And The "darwin-wallace Theory Of Evolution."

Though Darwin's name is virtually synonymous with the theory of evolution, the name of his codiscoverer Alfred Russel Wallace (1823–1913) is very often forgotten or relegated to the role of minor player. Yet Wallace himself was a gifted naturalist who distinguished himself for his scientific insights, especially in understanding island biogeography, and for his literary talents, especially excelling in the genre of the travel narrative.

Unlike Darwin, Wallace was born to a family of modest means in Usk, Monmouthshire, England. Lacking an extensive formal education, Wallace was an autodidact, frequenting lending libraries and attending public lectures on science. His first formal job at the age of fourteen was assisting his older brother at surveying counties in England, which gave him technical skills at observation and measurement, and he was later appointed as drawing master at the Collegiate School in Lancaster, where he fell in with Henry Walter Bates (1825–1892), a fellow teacher who shared a passion for the natural world.

In 1848 the two friends decided to embark on joint careers as commercial collectors of precious natural history specimens by traveling to the Amazon. They eventually took separate routes, collecting in increasingly unexplored regions, with Wallace traveling extensively up the Rio Negro, a tributary of the Amazon River. In 1852 Wallace returned to England, but nearly all of his magnificent collection was lost when his ship caught fire and sank. Wallace recovered from his setback rapidly, writing his account of the expedition in 1853, mostly from memory, as A Narrative of Travels on the Amazon and Rio Negro.

One year later he was once again in search of commercial specimens, this time setting off to the Malay Archipelago, where he traveled for nearly eight years. During this time he made one of the most notable observations in the history of island biogeography now associated with "Wallace's Line," an imaginary line that separated the two islands of Bali and Lombock; entirely different flora and fauna existed on either side of this geographic line. This disjuncture was only understood in the later twentieth century as the product of continental drift (the two areas are on separate plates).

Wallace's acute observations also led to his formulation, independently of Darwin, of a general theory of evolution that included a process closely resembling natural selection. In 1858, while suffering from malarial fever, Wallace connected the ideas of Malthus with his observations of the distribution of plants and animals and quickly drafted his celebrated paper "On the Tendency of Varieties to Depart Indefinitely from the Original Type." He proceeded to send the completed paper to Darwin, with whom he had had some previous correspondence. Darwin received the letter and immediately recognized the parallel views that Wallace had independently formulated. To avoid an unseemly priority dispute, Darwin turned over Wallace's paper along with his own historical sketch, essay, and correspondence with Asa Gray documenting the independence of the two efforts to Charles Lyell and Joseph Hooker and relied on them to negotiate the awkward situation. Both these men communicated these documents and a joint paper written by Darwin and Wallace to the Linnaean Society on 1 July 1858. Later that year the joint paper titled "On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection," by Charles Darwin and Alfred Wallace, was published in the Journal of the Proceedings of the Linnaean Society. Strangely enough, the paper failed to garner much negative attention or controversy. A year later, Darwin completed the famous "abstract" of his theory, published as On the Origin of Species, and from that point on Wallace's original contribution played at best only a supporting role.

Wallace himself was generally pleased to play this lesser part. He was a lifelong friend and supporter of Darwin, serving finally as pallbearer at Darwin's funeral with Huxley and Hooker. Darwin in turn supported Wallace through some especially difficult times, helping him secure a government pension. Wallace never properly attained financial security, and he also continued to uphold some radical ideas for his day that included land nationalization and an extreme opposition to vaccination campaigns in addition to more popular causes such as women's suffrage, labor reform, and universal education. Most disturbing to many establishment Victorian scientists generally, and Darwin in particular, was Wallace's growing support of spiritualist movements: Wallace's own support of the materialistic and mechanistic natural selection made an exception of the evolution of the human mind; he believed the "human spirit" could continue to progress even after the process of death.

His scientific work continued, earning him a permanent place in the history of science. Especially noteworthy were his contributions to island biogeography, which included the publication of The Geographical Distribution of Animals in 1876 and Island Life in 1880. In the late twentieth century Wallace's initial insights on the ecological dynamics of smaller island populations provided the intellectual backdrop to sciences such as conservation biology and to biodiversity studies.

Additional topics

Science EncyclopediaScience & Philosophy: Evolution to FerrocyanideEvolution - Evolution As A Theory Of Species Change, Charles Darwin And Descent With Modification By Means Of Natural Selection