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
Genetics and the Origin of Species whiz by." The book began as a series of lectures at Columbia University in October and November 1936. Dobzhansky decided to attend the summer 1936 meeting of the Genetics Society of America in Woods Hole, Massachusetts. When the geneticist Leslie Dunn learned of this, he invited Dobzhansky to give a series of lectures at Columbia. He sent the invitation in April, and within a month he had suggested that the lectures be a springboard for writing a general treatise on evolutionary genetics. Dobzhansky was enthusiastic, and in May he wrote back, proposing the title "Genetics and the Origin of Species".