The Hippocratic oath keeps it simple, reminding physicians that first, they must do no harm. No one in medical history violated that canon with more murderous zeal than Germany's Dr. Mengele.

The son of a Bavarian industrialist, Mengele joined the Nazi Party in the 1930s and began studying the sham science of "racial hygiene." In 1943 he became medical chief at Auschwitz-Birkenau, where he sent more than 400,000 non-Aryan prisoners to the gas chambers. On the side, he engaged in all manner of experimental butchery--dripping chemicals into prisoners' eyes to see if he could turn them a more Reich-pleasing blue, exposing others to infectious diseases to watch how different races respond to pathogens.

When the war ended, Mengele fled to South America. He died there in 1979 and was buried quietly under an assumed name. His remains were disinterred and identified in 1985--a too late bit of proof that even the Ubermensch can come to an ignoble end.

He was Joseph Stalin's favorite scientist, and it's easy to see why. Lysenko was a peasant-born agronomist and Marxist ideologue who rejected Mendel's ideas because they contradicted the doctrine of dialectical materialism. He offered instead to solve the Soviet Union's chronic crop failures through a process he called vernalization, by which he would "train" spring wheat to be winter wheat and thus increase the number of annual harvests. Lysenko believed all living organisms passed on to succeeding generations characteristics acquired in their lifetime. This untested theory was at odds with what Lysenko scathingly called "alien bourgeois" genetics, but Soviet scientists who dared disagree risked being sent to the gulag. The cost was high. Even after Lysenko's final fall at the end of the Khrushchev era, Soviet agriculture continued to suffer. Worse still, Soviet scientists missed out on the genetics revolution. To this day, Russian biology lags behind that of the West, thanks to Comrade Lysenko.