Barbara McClintock (1902-1992). American geneticist who, working with maize cytogenetics through the 1940s and 1950s, discovered transposable genetic elements — jumping genes — that move within and between chromosomes. The discovery was rejected by the genetics community for thirty years because it did not fit the contemporary picture of the gene as a stable, fixed unit. McClintock retreated from publishing and continued her work in near-isolation at Cold Spring Harbor, confident the discovery would be vindicated when molecular biology caught up. It was. She received the Nobel Prize in 1983, alone (a rare occurrence), at eighty-one years old. Her cognitive signature is the discovery specialty operating across decades of professional dismissal: monotropic focus on a system she understood better than anyone else in her field, refusal to abandon a result she knew was correct, and a readiness to wait out the integration apparatus until it could finally receive the work. "If you know you are on the right track," she said in her Nobel lecture, "if you have this inner knowledge, then nobody can turn you off."