Leonard Darwin, son of the illustrious Charles Darwin and longtime president of the British Eugenics Society, invoked historical precedent as the prime rationale for promoting eugenic reproductive policies. With the abundance of discoveries of extinct animal species and archaeological excavations of the Egyptians, Mayans, Aztecs, and Incas, the rise and fall of empires and of species was a tale told often in the nineteenth century, such that for Leonard Darwin in the 1920s, the rise-and-fall tendency of nature and of history had come to seem natural, inexorable-in a word, scientifi c. “It is now common knowledge,” reported Darwin in The Need for Eugenic Reform (1926), “that ancient civilizations in past ages often only arose to disappear or to decline into obscurity after a few centuries of brilliancy.”1 Seizing on this “common knowledge,” Leonard Darwin and many of his fellow eugenics proponents on both sides of the Atlantic stressed the urgency of the legislative adoption of their eugenic reforms, reasoning, “does it not seem probable, judging by past evidence, that our civilization will fade away also, unless some hitherto untried safeguards are adopted?”2