Wallace delivered this paper to the polygenist Anthropological Society of London on 1 March 1864. It represents “the first effort to connect natural selection to the touchy problem of the evolution of human races” (Wallace 1991, 26), a topic that Huxley broached in his Evidence of Man's Place in Nature (1863) but which Darwin avoided until his Descent of Man (1871).

Wallace argued that man is fundamentally different from all other species because of the nature of the human mind, which enabled him “to remove his body from the modifying influence of external conditions, and the cumulative action of natural selection.” Though Wallace shares credit with Darwin for the theory of evolution by natural selection, Wallace differed fundamentally from Darwin in his attempt to distinguish the effect of natural selection upon man from its effect on the rest of living things.