Hermann Joseph Muller

Hermann Joseph Muller was an American geneticist, educator, and Nobel laureate best known for his work on the physiological and genetic effects of radiation (Mutagenesis) as well as his outspoken political beliefs.^[2] Muller frequently warned of long-term dangers of radioactive fallout from nuclear war and nuclear testing, which resulted in greater public scrutiny of these practices.

Childhood & Early Life

· Muller was born in New York City, the son of Frances (Lyons) and Hermann Joseph Muller, Sr., an artisan who worked with metals. Muller was a third-generation American whose father's ancestors were originally Catholic and came to the United States from Koblenz.

· His mother's family was of mixed Jewish (descended from Spanish and Portuguese Jews) and Anglican background, and had come from Britain.^[3]^[4] Among his first cousins are Herbert J. Muller and Alfred Kroeber whose daughter is Ursula LeGuin.

· As an adolescent, he attended a Unitarian church and considered himself a pantheist; in high school he became an atheist. He excelled in the public schools. At 16 he entered Columbia College. From his first semester he was interested in biology; he became an early convert of the Mendelian-chromosome theory of heredity — and the concept of genetic mutations and natural selection as the basis for evolution.

· He formed a Biology Club and also became a proponent of eugenics; the connections between biology and society would be his perennial concern. Muller earned a B.A. degree in 1910.

· Muller remained at Columbia (the pre-eminent American zoology program at the time, thanks to E. B. Wilson and his students) for graduate school. He became interested in the Drosophila genetics work of Thomas Hunt Morgan's fly lab after undergraduate bottle washers Alfred Sturtevant and Calvin Bridges joined his Biology Club.

· In 1911-1912, he studied metabolism at Cornell University, but remained involved with Columbia. He followed the drosophilists as the first genetic maps emerged from Morgan's experiments, and joined Morgan's group in 1912.

· In the fly group, Muller's contributions were primarily theoretical: explanations for experimental results and ideas and predictions for new experiments. In the emerging collaborative culture of the drosophilists, however, credit was assigned based on results rather than ideas; Muller felt cheated when he was left out of major publications.

Career

· In 1914, Julian Huxley offered Muller a position at the recently founded William Marsh Rice Institute, now Rice University; he hurried to complete his Ph.D. degree and moved to Houston for the beginning of the 1915-1916 academic year (his degree was issued in 1916). At Rice, Muller taught biology and continued Drosophila lab work.

· In 1918, he proposed an explanation for the dramatic discontinuous alterations in Oenothera larmarckiana that were the basis of Hugo de Vries's theory of mutationism: "balanced lethals" allowed the accumulation of recessive mutations, and rare crossing over events resulted in the sudden expression of these hidden traits. In other words, de Vries's experiments were explainable by the Mendelian-chromosome theory. Muller's work was increasingly focused on mutation rate and lethal mutations.

· In 1918, Morgan—short-handed because many of his students and assistants were drafted for the U.S. entry into World War I—convinced Muller to return to Columbia to teach and to expand his experimental program.

· At Columbia, Muller and his collaborator and longtime friend Edgar Altenburg continued the investigation of lethal mutations. The primary method for detecting such mutations was to measure the sex ratios of the offspring of female flies. They predicted the ratio would vary from 1:1 due to recessive mutations on the X chromosome, which would be expressed only in males (who lacked the functional allele on a second X chromosome).

· Muller found a strong temperature dependence in mutation rate, leading him to believe that spontaneous mutation was the dominant mode (and to initially discount the role of external factors such as ionizing radiation or chemical agents). In 1920, Muller and Altenburg coauthored a seminal paper in Genetics on "modifier genes" that determine the size of mutant Drosophila wings.

· In 1919, Muller made the important discovery of a mutant (later found to be a chromosomal inversion) that appeared to suppress crossing-over, which opened up new avenues in mutation rate studies. However, his appointment at Columbia was not continued; he accepted an offer from the University of Texasand left Columbia after the summer of 1920.

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Major Work

· 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).

· When Muller returned to the United States in 1940, he took an untenured research position at Amherst College, in the department of Otto C. Glaser. After the U.S. entry into World War II, his position was extended indefinitely and expanded to include teaching. His Drosophila work in this period focused on measuring the rate of spontaneous (as opposed to radiation-induced) mutations. Muller's publication rate decreased greatly in this period, from a combination of lack of lab workers and experimentally challenging projects.

Awards

· In 1946 Muller was awarded the Nobel Prize in Physiology or Medicine, "for the discovery that mutations can be induced by x-rays".

Personal Life & Legacy

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.
Muller is survived by his daughter, Helen J. Muller, now a professor emerita at the University of New Mexico, who has a daughter, Mala Htun. His son, David E. Muller, a professor emeritus of mathematics and computer science at the University of Illinois and at New Mexico State University, died in 2008 in Las Cruces, New Mexico. David's mother was Jessie Jacobs Muller Offermann, Hermann's first wife. Helen's mother was Dorothea Kantorowicz Muller, Hermann's second wife.

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Hermann Joseph Muller

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