McCLINTOCK, Barbara, American geneticist, 1902-1992. Her work was mainly at Cornell U., and then Cold Spring Harbor Lab (Long Island). The early work involved looking at maize chromosomes and cytological markers (collaborating with Rhoades and Beadle). They jointly produced a notable publication in 1931. Then 20 years later Barbara published a theory concerning jumping genes. She had realised that genes change their position on a chromosome in random manner from one generation to another. This is an explanation for multiplicity of species, and of how identical cells can take on different specialised functions The Nobel Prize awarded her in 1983 (Medicine) was not a joint award, which is unusual in recent years. The phenomenon that she discovered became known as Jumping Genes. What was also unusual is that she had retired in 1967, but continued to work until her death, and this major discovery was made long after her retirement. This concept irritated other researchers and the theory would have taken many years to prove. But Barbara’s experimental results proved that genes are not evenly distributed and do not rigidly follow a line of descent (in terms of heredity), so her persistence finally paid off. From 1965 she held the Chair Professorship of Genetics at Cornell U. Only the 3rd woman to be elected to membership of the NAS, President of the Genetics Society in 1944, and awarded the National Medal of Science in 1970. A member of the National Women’s Hall of Fame from 1986.