On the Origin of Species for Existence" Darwin includes "slow-breeding man" among other examples of Malthusian population growth. In his discussions on morphology, Darwin compares and comments on bone structures that are homologous between humans and other mammals. Darwin's early notebooks discussed how non-adaptive characteristics could be selected when animals or humans chose mates, with races of humans differing over ideas of beauty. In his 1856 notes responding to Robert Knox's "The Races of Man: A Fragment", he called this effect sexual selection. He added notes on sexual selection to his "big book on species", and in mid-1857 he added a section heading; "Theory applied
Reactions to On the Origin of Species & Natural (as far as Final Causes & Design are concerned) on the other. The range & mass of knowledge take away one's breath." To Fanny Wedgwood she wrote, "I rather regret that C.D. went out of his way two or three times to speak of "The Creator" in the popular sense of the First Cause... His subject is the 'Origin of Species' & not the origin of Organisation; & it seems a needless mischief to have opened the latter speculation at all – There now! I have delivered my mind." The Revd. Adam Sedgwick had received his copy "with