What were the origins of the Nazi theory of the Master Race? Yes, by the 1920s there was a growing body of "research" from German biologists that dealt with racial differences. But by far the most influential and "advanced" work was coming from the American eugenics movement.
Richard Conniff has a fascinating article on the key role of Yale University professors and alumni in this sad chapter of American academic history:
"Proponents of eugenics included Yale president James R. Angell, celebrated football coach Walter Camp ’80, primatologist Robert Yerkes, and Yale medical school dean Milton Winternitz. Stewart Paton, who pioneered mental health services for college students during a two-year stint at Yale in the 1920s, was a eugenicist. So was Rabbi Louis L. Mann, a lecturer at Yale, who told an audience at a 1923 birth control conference that, even in ancient times, the wise men of Israel had realized the necessity of checking the multiplication of the unfit."
The seminal work of the American eugenics movements was a 1916 book by Yale graduate Madison Grant - The Passing of a Great Race - which extolled the superiority of Nordic stock and warned against its "corruption" by Jews, Blacks, Slav and any other race that lacked blond hair and blue eyes. In 1930 Madison Grant received a letter of thanks and appreciation from a rising political star in Germany - recently released from prison - Adolf Hitler. His book Mein Kampf displays an intimate knowledge of Grant's theories, as well as anti-immigrant and racial legislation in the United States, which Hitler believed Germany should adopt immediately.
And, once in power, Hitler implemented eugenic principles in ways the American proponents could only dream of. While sterilizations were common in the US, the Americans watched in wonder and admiration as the Nazis introduced systematic euthanasia - and then extermination on a mass scale.
As a Harvard PhD, I wish I could take some pleasure on this terrible blemish on the history of Yale University - a dreaded rival. But Harvard was also a hotbed of eugenics - indeed it was the center of eugenics research. Charles Davenport, a Harvard-trained biologist, was the leading figure in the American eugenics movement, and a key advisor to the American Eugenics Society.
Another, unrelated, Harvard connection was Ernst "Putzi" Hanfstaengl, Hitler's early advisor and a Harvard man through and through (see Hitler's Piano Player)