Morgan, Thomas Hunt (1866–1945), a United States geneticist. During 1909–15, Morgan and his assistants discovered three essential principles of genetics—sex linkage, linkage and crossing over, and sex determination. He discovered that genes are arranged within chromosomes in predictable patterns, and proved that chromosomes and genes determine hereditary traits. His experiments were conducted with the common fruit fly. He received the 1933 Nobel Prize in physiology or medicine.
Morgan was born in Lexington, Kentucky. He graduated from the State College of Kentucky (now University of Kentucky) in 1886 and received his Ph.D. from Johns Hopkins University in 1890. He was a professor at Bryn Mawr College, 1891–1904, and Columbia University, 1904–28. In 1928 Morgan became director of the Kerckhoff biological laboratories at California Institute of Technology. Morgan's Theory of the Gene (1926) sums up his work.