Good breeding: Darwin doubted his own family's "fitness."

Natural History, Nov, 2005 by James Moore

In the 1860s Darwin's own half-first cousin Francis Galton, who compiled Darwin's plant data, proposed to improve Britain's human "stock" through selection in marriage. Darwin thought the scheme "Utopian," but he knew the importance of statistics about fertility. A national census was to be conducted in Britain in 1871, and Darwin asked Parliament to insert a simple, relevant question, asking whether the respondent was married to a first cousin. That information, together with the number of surviving children listed in the census, would be telling. If cousin couples could be shown to produce fewer surviving children than unrelated spouses, there would be a scientific basis for a social policy banning close-cousin unions.

In Parliament a hot debate erupted. Members declared the question "inquisitorial" and "the grossest cruelty ever thought of." Imagine children being "anatomised by science," like "plants and animals"! First cousins might be banned from marrying, causing "mental torture" to couples. Darwin's question was thrown out by a margin of two to one.

The snub hurt. In his 1871 book, The Descent of Man, Darwin berated the "ignorant members of our legislature [for] rejecting with scorn a plan for ascertaining by an easy method whether or not consanguineous marriages are injurious to man."

Darwin turned to his son George--now a Cambridge mathematician, but still sickly, despondent, and expecting to die. George perked up at the prospect of compiling statistics on cousin marriage, and collaborated on the project with Charles's cousin Francis Galton.

In 1883, soon after Darwin's death, Galton was the first to dub the quest for good breeding "eugenics," and in 1907 helped to found the Eugenics Education Society. The Darwin sons joined, and Leonard became president in time to host the First International Congress of Eugenics in London in 1912.

Still childless himself as he pressed for the eugenic improvement of Britain, Leonard went on to mentor a "son" of his own, the brilliant young population geneticist Ronald A. Fisher. In 1930, Fisher became an architect of the so-called synthetic theory of evolution with his classic, The Genetical Theory of Natural Selection [see "On Darwin's Shoulders" by Douglas J. Futuyma, page 64]. Fisher dedicated the book to Leonard, whose eugenic commitments he shared, both of them knowing--as Leonard well recalled--that "Darwin was just as anxious as his cousin [Galton] to see practical steps taken to promote the gradual improvement of our race through the agency of natural inheritance."