Charles Darwin's theories of evolution by natural selection rocked the scientific world in 1859, and prompted his cousin, Galton, to study human evolution. Galton's first book, Hereditary Genius (1869), analyzed famous European families and concluded that "genius," which he defined as the ability to succeed in life, tended to run in families. Galton believed that individuals inherited the traits that destined them to either success or failure. Thus, success resulted from biology, not from the wealth or poverty of a person's background, and controlled breeding might permanently improve the human race.
Galton hoped to speed and direct human evolution. Writing in Inquiries into the Human Faculty and Its Development (1883), Galton defined eugenics as "the science of improving stock … to give the more suitable races or strains of blood a better chance of prevailing speedily over the less suitable than they otherwise would have had." Familiar with farmers' achievements in breeding more-valuable plants and animals, Galton believed that such methods were "equally applicable to men, brutes, and plants."
Galton identified those fit folk who should have children and stigmatized those he deemed unfit for parenthood. He also believed then-accepted notions of "racial" superiority and inferiority, had more to do with class and cultural prejudice than with biological difference. Galton assumed that wealthy people like himself were fit, whereas poor folk were unfit. Northern European "white" people stood atop the evolutionary scale of fitness, followed by "whites" from southeast Europe, Asians, Native Americans, Africans, and Australian Aborigines.