Hermann Joseph Muller

Hermann Joseph Muller (1890 to 1967) was an American geneticist, born in New York City, who won the 1946 Nobel Prize in Physiology or Medicine for discovering that X-rays produce mutations. He studied biology at Columbia College, joined Thomas Hunt Morgan's Drosophila group, and taught at the Rice Institute, Columbia and the University of Texas before later posts including Indiana University. His fruit fly work showed that the number of observed mutations rose with the dose of X-rays and other ionizing radiation, and his work on mutation rates, lethal mutations and balanced lethals helped confirm the Mendelian chromosome theory of heredity. He also took part in the early eugenics and human genetics debates, including a study of twins separated at birth, and later warned of the long-term genetic dangers of radioactive fallout from nuclear war and nuclear testing, which brought greater public scrutiny to those practices.