Hermann Joseph Muller

Geneticist

• Born: December 21, 1890
• Birthplace: New York, New York
• Died: April 5, 1967
• Place of death: Indianapolis, Indiana

American biologist

As the first scientist to induce mutations with X-rays, Hermann Joseph Muller founded the field of radiation genetics. He later became a crusader for radiation protection.

Born: December 21, 1890; New York City, New York

Died: April 5, 1967; Indianapolis, Indiana

Primary field: Biology

Specialty: Genetics

Early Life

Hermann Joseph Muller was a third-generation American whose paternal grandparents had emigrated from Koblenz, Germany, around 1848. When Muller was ten, his father died of a stroke, leaving his mother to support the family on a meager shop income.

Muller was a gifted student, receiving scholarship support to study at Columbia College, where he obtained his bachelor’s degree in 1910. Muller’s love for science settled in the new field of genetics, which he explored in coursework with geneticists Edmund Beecher Wilson and, later, Thomas Hunt Morgan. Joining Muller in his enthusiasm for genetics were two students who entered Columbia two years after he did, Calvin Blackman Bridges and Alfred H. Sturtevant. These five scientists were the major contributors to the development of classical genetics, the theory of the gene, and the field of cytogenetics.

After receiving a master’s degree in physiology in 1912, Muller was able to secure Morgan as his dissertation supervisor. Between 1910 and 1915, when Muller completed the work for his PhD, Morgan’s “fly lab”—so called due to their work with fruit flies (Drosophila)—had introduced the concepts of sex-linked inheritance and crossing-over, the mapping of genes, and the relation of genes to character formation. Some of the work involved individual discovery, but much of it was a cooperative effort among what was one of the first research teams.

Morgan and Muller differed in scientific style. Morgan favored experimental data that forced a theory to emerge, while Muller preferred reasoning before launching experiments. Muller believed that all biological phenomena ultimately stemmed from the activity of genes, and he tried to interpret all heredity through this model. As a theoretician, Muller provided abundant models and insights into the new discoveries, but Morgan only gave credit to the careful execution of experiments. Muller felt resentful that Morgan supported Sturtevant and Bridges financially, while he had to support himself with time-consuming jobs that were unrelated to his research. This eventually led to Muller’s estrangement from the fly lab and a lifelong reputation as a difficult man.

Life’s Work

Muller’s major theoretical contributions to genetics were in gene theory. He pointed out that genes are the only molecules that have the property of copying their errors and that, therefore, the copying property must be a fundamental feature of life. He clarified the concept of mutation, which was then believed to involve numerous abnormal processes, by restricting it to a change within the individual gene—what is now called a gene mutation. He extended the primacy of the gene to evolution and asserted that the gene is the basis of life, life having originated with the first replicating molecule capable of copying its variations. These ideas, developed between 1920 and 1926, were frequently resisted as fanciful or naively speculative by many of his contemporaries, but they gradually gained acceptance after the molecular revolution of the 1950s, when the chemical structure of genes proposed by James D. Watson and Francis Crick provided a material basis for these views.

Muller designed complex genetic stocks that enabled geneticists to repeat the work of others and to use them as tools for genetic studies, both theoretical and applied. In 1916, after receiving his PhD, he joined the faculty at the newly founded Rice Institute. He returned to Columbia in 1920, while Morgan was on leave, and then secured a position at the University of Texas, where he worked from 1920 to 1932.

During these years, Muller pursued the study of genes and mutations. He demonstrated that mutation frequency is measurable and affected by temperature. He proved that gene mutation is not restricted to the process of sperm or egg formation but can occur throughout the life cycle. He studied environmental effects by comparing the behavioral and physical traits of a pair of identical twins reared apart, concluding that it would take an army of experts to tease apart the genetic and environmental components of human behavior.

In 1926, Muller made the most important experimental contribution of his career. After reviewing the literature on biological effects of radiation, he reasoned that X-rays might damage individual genes. With his carefully designed stocks, he conducted an experiment proving that ionizing radiation produces mutations. This work, which he reported in 1927 to the International Congress of Genetics in Berlin, was rapidly confirmed by many geneticists, and Muller became an international celebrity and the leading authority on radiation genetics.

In the years that followed, Muller and his students showed that gene-mutation frequency rises proportionally to the dose received, and that there is no apparent threshold dose, since low or attenuated doses spread out over a month induced the same number of mutations as an identical dose administered over a short interval of time. Muller also demonstrated that ionizing radiation induces chromosome breakage, which results in changes such as the rearrangement of gene sequences, loss of chromosomes, and fatal early abortions of the Drosophila embryos that received radiation-damaged sperm or eggs. In 1945, Muller and his students applied these findings to interpret the mechanism of radiation sickness among the victims of the atomic bombings in Hiroshima and Nagasaki.

Muller supported the Bolsheviks and visited the Soviet Union in 1922 to set up research programs in fruit-fly genetics. He attracted postdoctoral students from the Soviet Union to his Texas laboratory. In 1932, he helped edit and distribute an underground newspaper, the Spark, and the FBI kept him under surveillance. He criticized the US eugenics movement in a paper he delivered at the third and last International Congress of Eugenics. That same year, he left Texas for Berlin on a Guggenheim Fellowship, but the Nazis came to power before the year was over, and Muller accepted an invitation to set up a laboratory in the Soviet Union.

Between 1933 and 1937, at Leningrad (now Saint Petersburg) and then in Moscow, Muller worked at a flourishing research school that studied problems of gene size, shape, boundaries, and number. This work was interrupted in 1936 by the arrest and execution of two of Muller’s students and the growing disapproval of Trofim Denisovitch Lysenko, who had the Communist Party’s support to replace genetics with a theory of environmental modification, or trained heredity. Muller and Lysenko clashed in public debate, and by 1937, Muller realized that the cause was lost. He escaped by volunteering to fight in the Spanish Civil War.

After the siege of Madrid, Muller was given a job in Edinburgh. Once again, he established a productive laboratory with graduate students from many nations, only to find his work interrupted by the onset of World War II. In 1940, he returned to the United States as an interim professor at Amherst College, but he relinquished the job when the war ended in 1945. He was subsequently hired by Indiana University.

Muller was awarded the Nobel Prize in Physiology or Medicine in 1946. He continued to advocate the importance of genetics to the future of humankind until his death on April 5, 1967.

Impact

Muller was outspoken on genetics-related issues and the role of science in the public domain. He was a staunch critic of those who attacked the teaching of evolution in public schools, for example, and denounced Lysenko at a time when more liberal scientists looked on the genetics controversy in the Soviet Union as a clash between two worldviews. He criticized the medical profession for not protecting its own practitioners and for its paternalistic attitude regarding excessive radiation for patients. While he believed in a strong national defense, including weapons testing, during the years of the Cold War, he fought for radiation protection when the quantity of weapons-testing fallout began to reach dangerous levels.

Although Muller denounced the cruder eugenics of his generation, he championed differential breeding and favored the breeding of more intelligent, more cooperative, and healthier people as a response to the increasing number of mutations that he identified as a concern in industrialized nations. He believed in the potential of education and knowledge to transform humankind and rejected coercion as a basis for bringing about change.

Bibliography

Carlson, Elof Axel. Genes, Radiation, and Society: The Life and Work of H. J. Muller. Ithaca: Cornell UP, 1981. Print. The first full account of Muller’s life and scientific accomplishments, based on more than thirty thousand letters, his 375 published articles, and numerous interviews with his students, colleagues, and critics.

Crow, James F. “Timeline: Hermann Joseph Muller, Evolutionist.” Nature Reviews Genetics 6.12 (2005): 941–52. Print. Argues that Muller, one of the most significant geneticists of the twentieth century, was also an important evolutionist.

Jamieson, James. “Hermann J. Muller: Nobel Prize–Winning Eugenicist.” Mankind Quarterly 43.3 (2003): 291–304. Print. Examines Muller’s life and writings to describe his ideas about eugenics.