Important personalitiesBack

Hermann Joseph Muller (or H. J. Muller) (December 21, 1890 – April 5, 1967) was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation (X-ray mutagenesis) as well as his outspoken political beliefs. Muller frequently warned of the long-term dangers of radioactive fallout from nuclear war and nuclear testing, helping to raise public awareness in this area.


Discovery of X-ray mutagenesis

1926 marked the beginning of a series of major breakthroughs. Beginning in November, Muller carried out two experiments with varied doses of X-rays, the second of which used the crossing over suppressor stock ("ClB") he had found in 1919. A clear, quantitative connection between radiation and lethal mutations quickly emerged. Muller's discovery created a media sensation after he delivered a paper entitled "The Problem of Genetic Modification" at the Fifth International Congress of Genetics in Berlin; it would make him one of the better known public intellectuals of the early 20th century. By 1928, others had replicated his dramatic results, expanding them to other model organisms such as wasps and maize. In the following years, he began publicizing the likely dangers of radiation exposure in humans (such as physicians who frequently operate X-ray equipment).

His lab grew quickly, but it shrank again following the onset of the Great Depression. Especially after the stock market crash, Muller was increasingly pessimistic about the prospects of capitalism. Some of his visiting lab members were from the USSR, and he helped edit and distribute an illegal leftist student newspaper, The Spark. It was a difficult period for Muller both scientifically and personally: his marriage was falling apart, and he was increasingly dissatisfied with his life in Texas. Meanwhile, the waning of the eugenics movement, ironically hastened by his own work pointing to the previously ignored connections between environment and genetics, meant that his ideas on the future of human evolution had reduced impact in the public sphere.