The Descent of Man and Selection in Relation to Sex, Vol. I

Darwin had avoided the question for years, human evolution was too 'surrounded with prejudices,' he admitted. But in 1871, he finally confronted what Origin of Species had left implicit: we are part of the animal kingdom, descended from lower forms, shaped by the same brutal logic of variation and selection. The Descent of Man is his audacious attempt to answer three questions: whether humans descend from some pre-existing form, how that development occurs, and what explains the variations among human races. Darwin's controversial solution was sexual selection, female choice among competing males driving the diverging characteristics not just of sexes but of populations. Through exhaustive comparative anatomy and psychology, he mapped the shared faculties of humans and lower animals, arguing that mental and moral capacities differ in degree, not kind. The book put apes in our family tree and made the races one family. Some of Darwin's racial hypotheses have not aged well, yet they were fired by his hatred of slavery and aimed against the more insidious polygenist belief that races had separate creations. This is the work that completed Darwin's argument, and still shapes how we think about what makes us human.