Childhood & Early Years
Thomas Hunt Morgan was born on September 25, 1866, in Lexington, Kentucky into an influential family of Southern planters. His father, Charlton Hunt Morgan, was a former Confederate officer. His mother, Ellen Key Howard Morgan, was from Maryland.
After the Civil War, because of their involvement with the Confederation, the Morgans lost some of their civil and property rights. Consequently, the family had to go through a tough period.
Young Thomas spent a lot of time wandering in the countryside of Kentucky and Maryland, collecting birds’ eggs and fossils. It created in him an interest in natural history, which remained with him till his death.
In 1880, Morgan was admitted to the preparatory department of the College of Kentucky. Then in 1882, he received admission in the main College. As an undergraduate student, he focused on science and enjoyed studying natural history.
In 1886, he graduated as valedictorian with a B.S. degree in zoology. He then spent the summer at the Marine Biology School in Annisquam, Massachusetts, before shifting to John Hopkins University in Baltimore.
At Hopkins, he studied general biology, anatomy, physiology, morphology and embryology, laying especial stress to morphology, which he studied under William Keith Brooks. After two years of work with Brooks at Hopkins, he received his M.S. degree from the State College of Kentucky in 1888.
Morgan chose sea spiders for his doctoral work and in 1890, received his PhD degree from Hopkins University. Subsequently, he started working for his postdoctoral at the same institute on Bruce fellowship. It allowed him to travel to Bahamas, Jamaica and Naples for further research.
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Career
Thomas Hunt Morgan completed his postdoctoral in 1891 and in autumn he was appointed as an Associate Professor of Biology at Bryn Mawr College. There he mainly taught the morphology related subjects.
Although he was a good teacher he was more interested in research work. He spent the first few years at the College researching on aquatic animals like sea acorns, ascidian worms and frogs.
Later in 1894, he took leave of absence for a year and went to Naples to conduct research in the laboratories of Stazione Zoologica. There he became familiar with the Entwicklungsmechanik School of experimental biology and completed an experimental study of ctenophore embryology.
Morgan was made a full professor in 1895. He now began to work on regeneration and development of larva, trying to distinguish between the external and internal causes. In 1897, he published his first book, ‘The Development of the Frog's Egg’.
Subsequently, he began a series of study on the capacity to regenerate in small animals like tadpoles, fish and earthworms. In 1901, he published his findings in another book called ‘Regeneration’.
Some time now, he also began his research on sex determination. In 1903, he published his third book, ‘Evolution and Adaption’, in which he accepted the process of evolution, but criticized Darwin’s theory of natural selection.
In 1904, Morgan shifted to the University of Columbia as Professor of Experimental Zoology. Here his researches focused mainly on hereditary and evolution, trying to prove De Vries' mutation theory experimentally. However, he was skeptical about Mendel's laws of heredity and also about the chromosomal theory of sex determination.
In 1908, Morgan started working on ‘Drosophila melanogaster’ (common fruit fly). He began by cross breeding these flies in order to find heritable mutations. Ultimately in 1910, Morgan found a male fly with white eyes among its red eyed wild sisters.
He then began to cross breed the white eyed mutant fly with its red eyed wild sisters and found that the males were always born with white eye while the females mostly had red eye. Although there were exceptions, the work showed for the first time the relationship between hereditary characters and specific chromosome.
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In fact, the papers Morgan published during 1909 and 1910 reflected his belief that chromosomes might be related to sex determination. However, until then he had not concluded that accessory chromosome X was the actual sex determiner.
In 1911, he published his finding in Science Magazine, in which he claimed that some traits were sex-linked and these traits were probably carried on one of the sex chromosomes. He also surmised that the other genes too were carried on specific chromosomes.
Morgan, along with his team of scientist, then accumulated thousands of mutant flies and began to study their complex inheritance patterns. In 1913, he published his findings in his fifth book, titled ‘Heredity and Sex’.
Slowly, he began to accept Mendel's laws and at the same time continued his research with fruit fly. Ultimately, in 1915, he integrated Mendel's theories with the Boveri–Sutton chromosome theory of inheritance and provided incontestable evidence for it.
Also in 1915, Morgan wrote a seminal book with Sturtevant, Calvin Bridges and H. J. Muller. Titled ‘The Mechanism of Mendelian Heredity’, the book is considered to be the fundamental book for the study of new genetics.
Morgan next began to concentrate on embryology. He encouraged his students to take up experimental approach in all fields of biology.
In 1927, Morgan received an offer to establish school of biology at the California Institute of Technology. Although he had by then neared the retirement age he took up the offer enthusiastically and shifted to California in 1928.
Morgan retired from the institute in 1942, but continued as professor and chairman emeritus until his death. The institution under him became a renowned center of research for experimental embryology, genetics and evolution, physiology, biophysics and biochemistry. He also established the Marine Laboratory at Corona del Mar.
Concurrently, he also held number of prestigious positions. For example, from 1927 to 1931 Morgan was the President of the National Academy of Sciences. In 1930 he became the President of the American Association for the Advancement of Science.
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Awards and Achievements
In 1933, Morgan was awarded with Nobel Prize in Physiology and Medicine "for his discoveries concerning the role played by the chromosome in heredity".
In 1924, Morgan received Darwin Medal from the Royal Society “For his valuable work in zoology and more especially his researches on heredity and cytology.”
In 1939, the Royal Society also awarded him Copley Medal "for his establishment of the modern science of genetics which had revolutionized our understanding, not only of heredity, but of the mechanism and nature of evolution".
In 1919, Morgan was made a Foreign Member of the Royal Society of London.
He received an honorary LL.D. from John Hopkins University and an honorary PhD from the University of Kentucky.
Personal Life & Legacy
In 1904, Thomas Hunt Morgan married Lilian Vaughan Sampson, an experimental biologist, who made significant contribution to his research on ‘Drosophila melanogaster’. She later became known for her discovery of attached-X chromosomes and ring chromosomes.
When they first met she was a student at Bryn Mawr and he was an associate professor at the same institute. In the initial years of their marriage, Lillian set aside her scientific career to raise their four children; one son and three daughters.
One of his daughters, Isabel Merrick Morgan, later became a virologist at Johns Hopkins University. She became known for her work on the preparation of an experimental vaccine to protect monkeys against polio.
Throughout his life Morgan suffered from a chronic duodenal ulcer. In 1945, when he was 79 years old, he experienced a severe heart attack. He died from a ruptured artery on December 4, 1945.
In 1989, Sweden issued a stamp to commemorate his discoveries. The Thomas Hunt Morgan School of Biological Sciences at the University of Kentucky has also been named in his honor.
