Abstract

In the standard narrative of her life, Barbara McClintock discovered genetic transposition in the 1940s but no one believed her. She was ignored until molecular biologists of the 1970s "rediscovered" transposition and vindicated her heretical discovery. New archival documents, as well as interviews and close reading of published papers, belie this narrative. Transposition was accepted immediately by both maize and bacterial geneticists. Maize geneticists confirmed it repeatedly in the early 1950s and by the late 1950s it was considered a classic discovery. But for McClintock, movable elements were part of an elaborate system of genetic control that she hypothesized to explain development and differentiation. This theory was highly speculative and was not widely accepted, even by those who had discovered transposition independently. When Jacob and Monod presented their alternative model for gene regulation, the operon, her controller argument was discarded as incorrect. Transposition, however, was soon discovered in microorganisms and by the late 1970s was recognized as a phenomenon of biomedical importance. For McClintock, the award of the 1983 Nobel Prize to her for the discovery of movable genetic elements, long treated as a legitimation, may well have been bittersweet. This new look at McClintock's experiments and theory has implications for the intellectual history of biology, the social history of American genetics, and McClintock's role in the historiography of women in science.