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women of science
Barbara McClintock
Barbara McClintock (1902 - 1992)

Recognition of her scientific accomplishments came late in life to Barbara McClintock. In 1983, when she was eighty-one, she was awarded the Nobel Prize in Medicine and Physiology for her discoveries in genetics. An intense and dedicated scientist, she had never sought the adulation that accompanies so prestigious a prize. Rather, in the many years that preceded her international recognition, she would have been content with an earlier understanding and acceptance of her findings.

Although she did not allow the general lack of support to deter her, she nevertheless had to overcome obstacles that could easily have discouraged a woman less persevering than herself. In 1936, when she was a young assistant professor in the botany department of the University of Missouri, the engagement announcement of a woman of the same name appeared in the newspapers. Mistakenly assuming the announcement to be that of Dr. McClintock, the department chairman warned her that if she was to be married, she would be fired--this ultimatum to a woman whose experiments in genetics had already created a stir in scientific circles and who was even then the vice president of the Genetics Society of America. Despite this daunting incident among others (she was also informed that she would be fired if her mentor left the university), McClintock was not without supporters. Chief among them was Marcus Rhoades, who had earned his Ph.D. under Thomas Hunt Morgan, and who joined her in her earlier years at Cornell in her project of mapping the genes of the maize plant.

Her association with the Marine Biological Laboratory began in 1927, when she was a student in the Botany course and was listed in the MBL records as Instructor in Botany at Cornell University. In that year, she earned her Ph.D. from Cornell.

Although many of her colleagues found her work difficult to understand, Marcus Rhoades considered even her early work worthy of a Nobel Prize. When Thomas Hunt Morgan visited Cornell in 1931, he was so impressed with her findings that he urged her to publish her experiments proving that the chromosomal exchange of genetic material produced new varieties. Shortly after her work was published, Curt Stern, the German geneticist, published similar findings from his work on fruit flies. Thanks to Morgan's urging, McClintock was first in the field. Her later experiments continued to alter the accepted picture of the stable chromosome revealing, among other findings, that damaged chromosomes mended themselves and sometimes fused together in rings.

After leaving the University of Missouri in 1941, McClintock joined the group of geneticists at Cold Spring Harbor, where she obtained the continuing financial support of the Carnegie Institution of Washington. It was at Cold Spring Harbor that she made her discovery of genetic transposition, the moving chromosomal parts being later called "transposons" or "jumping genes." Working with the more complicated maize plant, McClintock had identified these genetic elements twenty years ahead of the molecular biologists who were working with far simpler life forms. Scientists who had been skeptical of her findings now had to admit that the central dogma of DNA (i.e., DNA to RNA to protein) was no longer immutably fixed. Moreover, they could now see that their own research reiterated her findings on the existence of transposable genetic elements. The geneticist James Shapiro aptly summarized the sometimes acrimonious resistance that McClintock had encountered:

Transposable elements are an example of how new ideas are accepted coldly by the scientific community. If she says something has happened, she has seen it in dozens and hundreds of cases. One reason that people donÍt read her papers is because the documentation is so dense. So first they said sheÍs crazy; then they said it's peculiar to maize; then they said it's everywhere but has no significance; and then finally they woke up to its significance.

In the last quarter of her life, McClintock was honored with many awards and honorary degrees acknowledging the great importance of her work. Among these were degrees from Harvard and Rockefeller University, the lifetime fellowship MacArthur Laureate Award, the Lasker Award for Basic Medical Research, and the Wolf Foundation Award.

McGrayne, Sharon Bertsch. Nobel Prize Women in Science. Carol Publishing Group, 1993.

Keller, Evelyn Fox. A Feeling for the Organism. W. H. Freeman and Company, New York, 1983.

Barbara McClintock at the MBL. Photo taken outside of "Old Main" in 1927. -MBL Archives