Barbara McClintock (June 16, 1902 – September 2, 1992) was an American scientist and one of the world's most distinguished cytogeneticists. After receiving her PhD in botany from Cornell University in 1927, McClintock began studying chromosomes and how they change during reproduction in maize. She developed the technique for visualizing maize chromosomes and used microscopic analysis to demonstrate many fundamental genetic ideas. One of these was the notion of genetic recombination by crossing over during meiosis – a mechanism by which chromosomes exchange information. McClintock produced the first genetic map for maize, linking regions of the chromosome to physical traits. She also demonstrated the role of the telomere and the centromere, regions of the chromosome that are important in the conservation of genetic information. Recognized as among the best in the field, she received the 1983 Nobel Prize in Physiology or Medicine.
This 1947 photograph, in the collection of the Smithsonian Institution Archives, shows McClintock in her laboratory at the Cold Spring Harbor Laboratory in Laurel Hollow, New York.Photograph credit: Science Service, Smithsonian Institution; restored by Adam Cuerden