Curt Stern (30 August 1902 – 23 October 1981) was a German-American geneticist  of Jewish descent. Born in Hamburg, Germany, he studied zoology at the University of Berlin, receiving his PhD in 1923 at the age of 21. He was selected for a fellowship to study at Columbia University, then the site of Thomas Hunt Morgan's famous drosophila fly room.
Stern accepted an appointment at the University of Berlin after his fellowship ended. In 1931, he was the first to demonstrate crossover of homologous chromosomes in Drosophila melanogaster, only weeks after Barbara McClintock and Harriet Creighton had done so with maize.
Stern eventually returned to the United States in 1932. He became an American citizen in 1939. From 1933 to 1947, he taught at the University of Rochester. From 1947 until his retirement in 1970, he was a professor at the University of California, Berkeley, where he had numerous doctoral students.
In 1936, he demonstrated that recombination can also take place in mitosis resulting in somatic mosaics, organisms that contain two or more genetically distinct types of tissues. He later demonstrated that there were multiple genes on the Drosophila Y chromosome, and described the mechanism of dosage compensation.
During World War II, he led research for the American government on low dose radiation safety. His laboratory group concluded that there is no "safe" threshold below which radiation is not harmful.
After the war his research focused on human genetics, pioneering in what is now known as gene regulation. Although not a physician, he engaged in clinical work in human genetics. In 1943 he began teaching a course in human genetics to medical students at the University of Rochester. The first edition of Stern's pioneering textbook The Principles of human genetics was published in 1949. Both his teaching and his textbook were instrumental in re-founding human genetics on a non-racist basis, in contrast with pre-war German and American traditions in the subject. Stern was a signatory of the 1950 UNESCO statement The Race Question, a statement by leading scientists in many fields that questioned the validity and scientific foundations of racism.
The Curt Stern Award, established by the American Society of Human Genetics in 2001, recognizes a scientist who has made major scientific achievements in human genetics during the previous 10 years.
- "Dr Curt Stern, 79, Influential teacher of human genetics". New York Times. 1981-10-31.
- Stern, Curt and Sherwood, Eva R. (eds) 1966. The origin of genetics: a Mendel source book. Freeman, S.F.
- Burian, Richard M. (2000). "Stern, Curt, in American National Biography Online".
- Allgemeine Zeitschrift des Judenthums. Ein unparteiisches Organ fuer alles juedische Interesse. Volume 22, No 7. December 1857 page 92.
- Stern, Curt (1968). Genetic mosaics and other essays. Cambridge, Massachusetts: Harvard University Press.
- Stern, Curt (1973). Principles of human genetics (3rd ed ed.). San Francisco: W.H. Freeman.
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