(1947–    ), American biologist, geneticist, and Nobel laureate. Born in South Bend, Ind., Wieschaus was educated there at the University of Notre Dame and at Yale University in New Haven, Conn., where he received his Ph.D. in 1974. He did postdoctoral research at the University of Zürich, Switzerland, in 1975–78; at the CNRS’s Laboratory of Molecular Genetics at Gif-sur-Yvette, France, in 1976; and at the University of California at Irvine in 1977. For the next three years he worked at the European Molecular Biology Laboratory in Heidelberg, Germany. In 1981 Wieschaus returned to the U.S. to teach biology and molecular biology at Princeton University in Princeton, N.J.

With the German biologist and geneticist Christiane Nüsslein-Volhard, a colleague at the Laboratory in Heidelberg, Wieschaus continued the research on the genetics of the fruit fly, Drosophila melanogaster, initiated by the American biologist and geneticist Edward B. Lewis in the 1940s. Wieschaus and Nüsslein-Volhard bred thousands of generations of this insect to determine the causes of mutations in the genes controlling the formation of body segments in embryo stage. The results of their research—a breakthrough that helped explain congenital malformations in humans—were published in an article, Mutations Affecting Segment Number and Polarity in Drosophila, in 1980.

In 1995 Wieschaus, Nusslein-Volhard, and Lewis were awarded the Nobel Prize in physiology or medicine for their discoveries concerning “the genetic control of early embryonic development.”

See also DEVELOPMENT,; EMBRYOLOGY,; FRUIT FLY,; GENETICS,.