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Nettie Maria Stevens and Edmund Beecher Wilson both independently developed the idea of sex determination by chromosomes. Their work established the importance of chromosomes in heredity and helped Thomas Hunt Morgan interpret the early genetic results from Drosophila.
NETTIE MARIA STEVENS (1861-1912)Nettie Stevens was one of the first female scientists to make a name for herself in the biological sciences. She was born in Cavendish, Vermont. Her family settled in Westford, Vermont. Stevens' father was a carpenter and handyman. He did well enough to own quite a bit of Westford property, and could afford to send his children to school. Stevens was a brilliant student, consistently scoring the highest in her classes. In 1896, Stevens went to California to attend Leland Stanford University. She graduated with a masters in biology. Her thesis involved a lot of microscopic work and precise, careful detailing of new species of marine life. This training was a factor in her success with later investigations of chromosomal behavior. After Stanford, Stevens went to Bryn Mawr College for more graduate work. Thomas Hunt Morgan was still teaching at Bryn Mawr, and was one of her professors. Stevens again did so well that she was awarded a fellowship to study abroad. She traveled to Europe and spent time in Theodor Boveri's lab at the Zoological Institute at Würzburg, Germany. Boveri was working on the problem of the role of chromosomes in heredity. Stevens likely developed an interest in the subject from her stay. In 1903, Stevens got her Ph.D. from Bryn Mawr, and started looking for a research position. She was eventually given an assistantship by the Carnegie Institute after glowing recommendations from Thomas Hunt Morgan, Edmund Wilson and M. Carey Thomas, the president of Bryn Mawr. Her work on sex determination was published as a Carnegie Institute report in 1905. In this first study she looked at sex determination in meal worms. Later, she studied sex determination in many different species of insects. Stevens' assistantship at Bryn Mawr still meant that she had to teach. She wanted a pure research position, and wrote to Charles Davenport to see if it was possible for her to work at his Station for Experimental Biology. Unfortunately, Stevens died of breast cancer in 1912 before she could occupy the research professorship created for her at Bryn Mawr, or work with Davenport at Cold Spring Harbor. EDMUND BEECHER WILSON (1856-1939)
Edmund Beecher Wilson was born in Geneva, Illinois. He was the son of a judge, but instead of law, Wilson chose to study biology at Yale University (1878). He did graduate work at Johns Hopkins University (1878-81). Wilson's training was in the field of embryology; genetics as a science did not exist at the time. Between the years of 1885-1891, Wilson was a professor at Bryn Mawr College and taught biological sciences; he also traveled to Europe to continue his own investigations. Cytology, the study of chromosomes, was becoming more important. Wilson soon became an expert, and began investigating the role of heredity in cellular development. In 1891, Wilson left Bryn Mawr to become a professor at the zoology department at Columbia University. He eventually became head of the zoology department. Wilson continued to have ties with Bryn Mawr. He was good friends with Thomas Hunt Morgan who taught there, and Wilson continued to help and advise students of Bryn Mawr. In 1904, Wilson invited Thomas Hunt Morgan to join the staff at Columbia, thereby helping to create the scientific atmosphere necessary for the interaction of cytology and genetics. In 1905, Wilson published a paper Studies on Chromosomes based on his studies of insect chromosomes. In this paper, Wilson advanced the theory of sex determination by chromosomes. In the same year, Wilson was asked to review Nettie Stevens' paper on the subject. Technically, Wilson's paper was already in press when he read Stevens' work (he heartily endorsed its publication). However, both Wilson and Stevens are credited with the theory of sex determination by chromosomes, since they arrived at it independently. Both Wilson and Stevens ended up referencing each other in their papers to support their conclusions. Wilson published a series of Studies on Chromosomes papers. He also published books on cellular structure and general biology. Wilson was a professional caliber cellist. He enjoyed sailing and would often invite Thomas Hunt Morgan and his family onto his boat. Herman Muller, one of Wilson's students, described him as a kind, scrupulous, careful man who was aware that ideas were useful only when communicated properly. Wilson's lectures were said to be organized, well-thought out and well-delivered. Wilson retired from Columbia in the early 1930's. |
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