Alfred Russel Wallace and Charles Darwin (1809-1882) were the first two significant evolutionists, each discovering natural selection independently of the other, but Darwin receiving most of the credit.

Wallace was born into a large, happy, middle-class family in Usk, Monmouthshire, Wales. While still a teenager, he became devoted to the utopian socialism of Robert Owen (1771-1858). He developed an interest in natural history while apprenticed as a surveyor to his older brother William in the late 1830s. William hired him in 1839 but laid him off in 1843. He then taught mathematics, English, drafting, and surveying at the Collegiate School in Leicester until 1845, when he returned to the surveying business.

In 1844, Wallace met Henry Walter Bates, with whom he set sail on 25 April 1848 to gather specimens in the Amazon basin. Bates wanted merely to collect and explore, while, in addition to that, Wallace's goal was to find organic evidence for...