The Descent of Man and Selection in Relation to Sex Volume 1

In his introduction, Darwin reveals that for many years he had no intention of publishing his notes on this topic, 'as I thought that I should thus only add to the prejudices against my views'. By 1871, he felt that his fellow scientists would show a greater openness of mind to his arguments, even when taken to their logical conclusion and applied to the descent of man from the apes – the aspect of his theory which had been so widely mocked since the notorious question asked by Bishop Wilberforce at the Oxford debate of 1860: was it through his grandmother or his grandfather that Thomas Huxley, Darwin's champion, considered himself descended from a monkey? However, the book's focus on the area of sexual selection and the evolutionary importance of secondary sexual characteristics across the animal kingdom meant that the book was received without the public outrage that Darwin had feared.

Introduction; Part I. On the Descent of Man: 1. The evidence of the descent of man from some lower form; 2. Comparison of the mental powers of man and the lower animals; 3. Comparison of the mental powers of man and the lower animals (continued); 4. On the manner of development of man from some lower form; 5. On the development of the intellectual and moral faculties during primeval and civilised times; 6. On the affinities and genealogy of man; 7. On the races of man; Part II. Sexual Selection: 8. Principles of sexual selection; 9. Secondary sexual characters in the lower classes of the animal kingdom; 10. Secondary sexual characters of insects; 11. Insects (continued)–Order lepidoptera.

Darwin's two-volume work on the area of sexual selection and the evolutionary importance of secondary sexual characteristics (such as the brighter plumage of male birds) across the whole of the animal kingdom.