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Muller with his jeweler's loupe, a fly viewing practice he picked up while working in the Morgan lab. (Photo in UT Zoology Archive, Dolph Briscoe Center for American History, The University of Texas at Austin)

By Nicole Elmer, August 24, 2016

Hermann Joseph Muller was a professor, geneticist, and Nobel laureate who is best known as the founder of the field of radiation genetics, in addition to being a co-founder of the American school of classical genetics. Much of the research that led Muller to the Nobel prize was done at UT Austin in the Biological Sciences building (BIO) during the 1920s. But for all the accolades Muller received for his work in genetics, he lived an intense personal and professional life and found himself in many political hotbeds of the world during his lifetime.

Muller identified as both an atheist and a humanist, and while an advocate of selective breeding for humanity, he was a vocal opponent of the American eugenics movement in the early 20th century, accusing it of racism and elitism. In addition, Muller was committed to Darwinism and supported natural selection as the basic mechanism of evolution, a view under attack in academia in the early part of the 20th century. His communist-leaning political beliefs also lead him into trouble with UT and the FBI, and ultimately drew him to Europe during World War II, where he saw the rise of Nazism and collided with Stalinism. In addition, his first marriage suffered immensely from the strain of his intense work hours and his outspoken beliefs. Nevertheless, Muller retained the respect of geneticists the world over.


Muller was born in New York City on December 20, 1890, to Hermann Joseph and Frances Lyons, both first-generation Americans. Hermann Joseph continued his own father's fine art metal business but sadly died of a cerebral stroke when young Hermann was only ten.

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 Muller in 1897, age 7 (Photo from the Lilly Library, Indiana University)

As a child, Muller displayed an early interest in science. It is believed he and his friends started what might have been the first high school science club in the US.

Muller would later earn his bachelors in zoology in 1910 at Columbia University but had the additional responsibility of supporting his mother and sister since his father had passed on. To help his family economically, Muller worked odd jobs while in school, serving as a runner on Wall Street and an English teacher to immigrants. While working towards his Masters in nerve physiology at Cornell, he taught physiology for a year at Cornell University Medical School and then returned to Columbia to complete his PhD.

During his graduate years at Columbia, Muller would quickly become involved in impactful work with fruit flies (Drosophila) that would forever influence his life direction. He worked in the famous "Fly Room" with geneticist Thomas Hunt Morgan, who brought Muller into his lab based on the reputation of Muller's prior work. Muller and Morgan had mismatched temperaments, with Morgan's more laissez-faire approach clashing with Muller, who did not like others getting credit for his work. 

Despite their differences, Muller played an important role in the Morgan laboratory. He wrote a series of papers on the mechanism of crossing-over of genes, and his thesis on crossing-over earning him his Ph.D. in 1916. Crossing-over refers to an exchange of genes between a pair of homologous chromosomes, resulting in a mixture of parental characteristics. Muller was also co-author, with Morgan and two other students, on The Mechanics of Mendelian Heredity, a landmark book that linked Gregor Mendel’s laws of heredity with discoveries about chromosomes, the bodies in the cell nucleus that Morgan’s group had shown to contain genes.

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 A lab party in Thomas Morgan's lab, 1919. Muller is seated next to Morgan, second from right in back. (Photo from the Lilly Library, Indiana University)


Despite the accomplishments of the Morgan lab and Muller’s desire to continue to work at Columbia, he would soon be leaving. Foundation Chair Julian Huxley of the Biology Department at the new Rice Institute was impressed with the work coming from the lab. On recommendation from Morgan, Muller did post-doctoral work at the Rice Institute in 1916 through 1917. He would return to Columbia from 1918 to 1920 where he would serve as interim professor while Morgan was on sabbatical.  Muller’s hope was that a more permanent faculty position would open up for him, but perhaps through various issues surrounding his strained relations with Morgan, the faculty position was not offered. Muller would return to Texas, but this time, to UT Austin. 


In 1920, Muller was hired as an Associate Professor by Dr. John T. Patterson, who believed in experimental zoology. Unlike his situation at Columbia where Muller had to put much of his own money towards lab supplies, Patterson made sure Muller had money for equipment and an assistant. The new Biological Laboratories (BIO) building that opened in 1925 provided Muller the luxury of a refrigeration unit to make studying of flies much easier than it had been in his earlier building in the Old Main, as the Texas heat would sterilize the flies.

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 The "Fly Room" in BIO. T.S. Painter sits to the left, W.S. Stone stands in the back, C.P. Oliver sits front, and Muller views flies through his jeweler's loupe. (Photo from the Lilly Library, Indiana University)

Muller had a profound effect on his colleagues at UT, specifically Patterson who was studying armadillo embryology and Theophilus S. Painter who was studying the cytology of spiders. When Muller showed them the use of Drosophila in genetic analysis, both professors switched their organisms of choice to this insect. While this increased the discussions and approaches, Muller soon felt he was putting too much time into his colleagues’ work and not enough into his own. In addition to his day hours, he would begin to work at night, seven days a week, sometimes sleeping on a cot. His contemporaries noticed Muller's avoidance of them, and this increased rivalry.

Muller's most important discoveries occurred between 1918 and 1926.  With Morgan, he became interested in mutations, for these occurred so rarely in nature that they were hard to study. Muller also believed that mutations were mostly recessive and would appear when two organisms carrying the mutated gene mated and passed on that gene to their offspring. This might not occur until generations after the mutation initially arose. Mutations also might not become visible if they caused death during embryonic development. 

Looking for a way to increase the frequency with which mutations occurred, Muller first tried heat in 1919 but found in 1926 that X-rays were far more effective. The machine that facilitated these X-ray experiments is still visible on campus, in one of the entrances of the MBB building. 

 Muller's X-ray machine currently housed in MBB

In a ground-breaking paper published in 1927, Muller announced that exposure to X-rays increased the frequency of mutations in fruit flies to 100 times their natural level. This was the first time a large number of mutations had been produced artificially and would provide the potential to advance the study of genetics considerably. The artificial creation of mutations helped to lay the foundation for genetic engineering.  Muller would be awarded the Nobel Prize in physiology or medicine in 1946 for this work.

In the second part to this article on Muller, we will take a look at the troubled times Muller experienced at UT before heading off to Europe.





Carlson, Elof Axel. Genes, Radiation, and Society: The Life and Work of H.J. Muller. Cornell University Press, 1981.

Carlson, Elof Axel. “Herman Joseph Muller 1890-1967. A Biographical Memoir.” National Academy of Sciences, 2009.

Carlson, Elof Axel. “Speaking Out About the Social Implications of Science: The Uneven Legacy of H.J. Muller.” January 2011. Genetics Society of America.

Crow, James F. Comment page in Discovery, 1994. Vol 13. No.4.

Goodstein, Judith. “The Thomas Hunt Morgan Era in Biology.” Engineering & Science, Summer 1991.

Green, Tim. “Hermann Muller: A genetics pioneer.” January 19, 2010. UTNews.

Yont, Lisa. Facts on File Science Library: Notable Scientists A to Z of Biologists, Facts on File 2003.

Wager, Robert P. and Crow, James F. “The Other Fly Room: J.T. Patterson and Texas Genetics.” Genetics Society of America, 2001.

“Eighty years ago, Texas researcher conducted X-ray experiments that won Nobel prize.” September 28, 2007. UTNews.