Marian Elliott "Bunny" Koshland (October 25, 1921 – October 28, 1997) was an American immunologist who discovered that the differences in amino acid composition of antibodies explain the efficiency and effectiveness with which they combat a huge range of foreign invaders. Biography Marian Elliott was born on October 25, 1921, in New Haven, Connecticut, to Margrethe Schmidt Elliott and Walter Elliott. Her mother was a teacher who had immigrated from Denmark and her father was a hardware salesman of Southern Baptist background. When she was four, her younger brother contracted typhoid fever, and she was tutored by two neighbor girls. She was something of a tomboy, befriending three Jewish boys with whom she would attend Works Progress Administration theater productions. She was the only girl in her class who dared to handle a three-foot black constrictor snake, for which she won a can of rattlesnake meat. Marian attended Vassar College in New York and graduated in 1942 with a degree in bacteriology. She then attended the University of Chicago, where she received her M.S. in bacteriology in 1943. In Chicago she worked on reducing the spread of respiratory diseases and was a member of a research team that developed a vaccine for cholera. While at Chicago she met Daniel E. Koshland Jr., a biochemist and heir to the Levi Strauss fortune. In 1945, she joined him in Oak Ridge, Tennessee and spent a year working on the Manhattan Project, researching the biological effects of radiation. The two married in 1946 and returned to Chicago, where Marian received her Ph.D. in immunology from the University of Chicago in 1949. Marian's sister-in-law later recalled that her professor did not want to give her a Ph.D. because Marian was pregnant and he thought she would waste it. In 1949, she moved with Daniel to Boston, where Marian spent two years in a postdoctoral fellowship at Harvard Medical School's Department of Bacteriology. They later both worked at the Brookhaven National Laboratory for 13 years. In the early 1950s, Marian Koshland demonstrated the molecular differences between serum-borne and secreted antibodies. By the 1960s, she had turned her attention to the origins of antibody specificity. Jim Allison, a colleague from Berkeley, said "Bunny analyzed polyclonal antibodies directed against two different haptens, and on the basis of exquisitely careful amino acid composition analyses, convincingly showed that these antibodies had different amino acid compositions and therefore must differ