Charles Darwin’s “The Descent of Man: And Selection in Relation to Sex” is his second work on his theory of evolution and natural selection. Originally published in 1871, Darwin applies evolutionary analysis to human development. He then narrows his focus to “sexual selection,” which he uses to explain various adaptations in species. The book was met with mixed reviews. Alfred Russel Wallace, a leading evolutionary theorist who is co-credited with discovering natural selection, disagreed with Darwin’s views on sexual selection. He argued that Darwin’s discussion of female choice attributed advanced cognitive function to species without such abilities, like insects. Wallace, however, was a believer in spiritualism and asserted that natural selection could not explain certain traits, like artistic ability, musical genius, or humor. Today, “The Descent of Man” remains as a must-read for anyone interested in biology, Darwinism and early evolutionary theory.