The Descent of Man, and Selection in Relation to Sex was published by John Murray in two volumes in February 1871, twelve years after The Origin of Species. Where The Origin had carefully avoided the question of human evolution (the only reference was the cryptic sentence “Light will be thrown on the origin of man and his history”), The Descent confronted it directly. Darwin argued, on the basis of anatomical, embryological, and behavioral evidence, that humans had descended from earlier primates — specifically from an ancestor shared with the great apes.
The book is divided into two parts. The first presents evidence for human evolution and addresses its implications for morality, religion, and race. Darwin argues that moral sense evolved through natural selection — that groups whose members cooperated and showed sympathy for each other outcompeted groups that did not. This was a radical claim: it meant that ethics, which had been considered a divine endowment, could be explained as a product of natural history.
The second part — roughly two-thirds of the book — is devoted to sexual selection, the process by which individuals of one sex choose mates based on characteristics that may have no survival value. The peacock’s tail, the stag’s antlers, birdsong, and human aesthetic preferences are all explained as products of mate choice. Sexual selection allowed Darwin to account for traits that natural selection alone could not explain — ornamental features that seemed to decrease survival while increasing reproductive success.
Collecting The Descent of Man
First edition (John Murray, London, 1871): Two volumes, green cloth binding.
Market values:
- First edition, two volumes, fine: $15,000–$40,000
- Very good: $5,000–$15,000
- Good (worn, foxed): $2,000–$5,000
- Second edition (1874, revised): $1,000–$3,000