Hermann Joseph Muller was the first to show that genetic mutations can be induced by exposing chromosomes to X rays. For this demonstration he was awarded the 1946 Nobel Prize in physiology or medicine. He also took up a crusade to improve the condition of the human gene pool by calling for a cessation of the unnecessary use of X rays in medicine and a halt to nuclear bomb testing in order to prevent further damage to the genetic makeup of the human population.

Hermann Joseph Muller was born on December 21, 1890, in New York City. His father was also named Hermann Joseph Muller; his mother was the former Frances Lyons. Muller's paternal grandfather had come to the United States from Germany after the revolution that had swept Europe in 1848. Muller's father had wanted to be a lawyer, but instead had taken up the family business of producing bronze art...