Enshrined as the co-discoverer of the theory of natural selection, Alfred Russel Wallace was a pioneering naturalist whose influence extended beyond evolutionary theory to biogeography, ecology, and sociology. Although his middling social origins and "radical" political and social beliefs limited his acceptance in the fold of elite English science, Wallace's undeniable ingenuity and originality made him an indispensable voice in discussions about natural history during the latter half of the nineteenth century.

Born January 8, 1823, the eighth of nine children of Thomas Vere Wallace and Mary Anne Greenell, Alfred R. Wallace was raised under what might be called modest middle class circumstances, but circumstances that were not untainted by financial hardship. As a result of his father's misfortunes with a swindler, Wallace was forced to withdraw from school at the age of thirteen, leaving home for London to live with his older brother John. Despite the painful events occasioning his departure from home, Wallace profited from his experience in one important way. In London, he fell into the orbit of a group of committed Owenite Socialists, whose heterodox political and social ideas he absorbed and maintained throughout the remainder of his life.

In 1837, Wallace moved to Bedfordshire to live with another brother, William, where he learned surveying and, for a brief time, he was apprenticed to a watchmaker. The basic technical skills he acquired, including mathematics, drafting, geology, and geography, combined with a steady diet of outdoor work whetted Wallace's appetite for natural history, which he nourished by attending lectures at the Mechanics' Institutes in Kington (Hereford) and Neath (Wales). When his brother laid him off from work in 1843, Alfred picked up work as an instructor in drafting, surveying, and arithmetic at the Collegiate School in Leicester, which he put to full advantage. Through the near availability of a suitable library, intensive self-study, and a developing friendship with the entomologist Henry Walter Bates, Wallace gradually strengthened his background in natural history.

As a result of these changes in fortune, when his brother William died, enabling a return to surveying, Alfred was primed to strike out in a different direction. Disinclined to wallow in the mundanities of surveying, he lit instead upon the notion of joining his friend Bates in an expedition up the Amazon to collect specimens and observe. Thus in April 1848, the two men left Pará (now Belém), Brazil, for a journey deep into Amazonia. After two years, Wallace and Bates separated, with Wallace returning to England in 1852 and Bates remaining in South American for nearly a decade longer. By any measure, their expedition was productive: Bates discovered a form of mimicry that still bears his name, while Wallace, already a convinced evolutionist from his reading of Charles Lyell's Principles and Robert Chambers' Vestiges of the Natural Creation, began in earnest what would become a lifelong inquiry into the mechanics of the evolutionary process.

Wallace's plans for a windfall from his expedition came to naught upon his return when a shipboard fire destroyed nearly all of the specimens he had painstakingly acquired in the Amazon. Although covered by insurance, barely, Wallace's plans for establishing a scientific name for himself could not so easily be resurrected. He produced two creditable works from his period in the Amazon -- the ethnobotanical Palm Trees of the Amazon and Their Uses (London, 1853) and A Narrative of Travels on the Amazon and Rio Negro (London, 1853) -- however these made no contribution to evolutionary theory, and had only modest returns for four hard-spent years.

However small, these returns turned out to be crucial. Drawing upon the strength of these publications, Wallace secured a grant from the Royal Geographic Society to undertake a naturalizing expedition to the Malay Archipelago, the site of what would become his most famous work. Arriving in Singapore in April 1854, Wallace spent eight years careering about Indonesia, collecting over 100,000 specimens and one thousand new species. His magnum opus, The Malay Archipelago (London, 1869), enjoyed great success in England as a travel narrative, as ethnographic study, and as a natural historical tour de force.

But more important in the long run, Wallace's Indonesian excursion quickened his thoughts on evolutionary change. Like the Galapagos had for Darwin, the spectacular biotic profusion of Indonesia propelled Wallace's evolutionary rumination, resulting in a seminal paper in the Annals and Magazine of Natural History 16 (1855), "On the Law Which Has Regulated the Introduction of New Species." In this first foray into what would become natural selection, Wallace sketched out an hypothesis for conceiving the spatial and temporal relationships of species, concluding that "every species has come into existence coincident both in time and space with a pre-existing closely allied species." Although Charles Lyell brought the paper to the attention of Darwin, Darwin appears nevertheless to have paid it little, if any attention.

Independently of Darwin, Wallace continued to assemble the theoretical framework of natural selection. As was true for Darwin, Malthusian economics provided a touchstone, propelling Wallace's second major paper on the subject, a draft of which was sent for Darwin's perusal in 1858. This time, Darwin did not fail to notice. The manuscript prodded Darwin into a furious fit of writing, resulting in a mutually agreed-upon simultaneous presentation of their works before the Linnean Society during the summer of 1858, and in 1859, the publication of Darwin's "abstract," On the Origin of Species.

Wallace remained in Indonesia for an additional four years, finally returning to England early in 1862. His publications and the massive collections he had accumulated in the Archipelago brought him a measure of financial comfort and high respect among British naturalists. There remained, however, always something of a distance between Wallace and his peers. While some of this may be attributed to the "inferiority" of Wallace's social origins, he differed even more fundamentally in other ways. Wallace could always be relied upon as a supporter of natural selection and evolutionary theory, but he represented a distinctly different strain.

Already distinguished by his Owenite political preferences, Wallace became further differentiated from the bulk of the Darwin crowd by becoming a convert to Spiritualism in 1866. Like most Spiritualists, he rejected the arch-materialism of Darwin and Huxley, and he never accepted that natural selection operated on the "higher" (spiritual and intellectual) aspects of humanity. Whether Spiritualism led him to these views, or these views led him to Spiritualism is difficult to discern, but the tenor of Wallace's work after 1870 took on a tenor unique among the prominent Darwinists. He was immensely prolific, writing popular and technical works in natural history that made him the best known naturalist in Britain by the end of the century, but he commented increasingly on issues of political and social concern to radicals, emerging as a full-fledged Socialist by the 1880s.

Active mentally and physically, as writer and lecturer, late into his 80s, Wallace died in his sleep at home on November 7, 1913.