Barbara McClintock

Hartford registered her at birth as Eleanor, and her parents changed it after deciding the name was too feminine and delicate for the child they had. From three until she started school she lived with an aunt and uncle in Brooklyn, sent away to ease the household while her father built a homeopathic practice. She was close to him and not to her mother, who resisted college for fear it would leave her daughter unmarriageable. Her father let her register at Cornell at the last moment in 1919. She was asked into a sorority, broke the pledge, and took up jazz. A genetics course in 1921 and a telephone call inviting her into the graduate course settled it: obviously, she said, that call cast the die.

She built the maize cytogenetics group at Cornell around Marcus Rhoades, George Beadle and Harriet Creighton, worked out a carmine stain that made the chromosomes visible, and gave the first description of the shape of all 10 of them. In 1930 she described the cross-shaped pairing of homologous chromosomes at meiosis. In 1931, with Creighton, she showed under a microscope that chromosomal crossover and the recombination of inherited traits are the same event. She was elected to the National Academy of Sciences in 1944, only the third woman, and led the Genetics Society of America the next year, the first woman to do it. That same summer, at Cold Spring Harbor, she started on the mottled maize kernels and found two loci she named Dissociation and Activator, which moved along the chromosome and switched genes on and off.

She described the response to the work as puzzlement, even hostility. She laid out the full statistics in Genetics in 1953 and then stopped publishing detailed accounts of controlling elements, judging that she was at risk of alienating the mainstream, though she kept lecturing about them through the decade. At Missouri she had been left out of faculty meetings and wrote in 1940 that 3,000 dollars as an assistant professor was her ceiling. What all that means is contested. Evelyn Fox Keller's A Feeling for the Organism made her the outsider whose exclusion sharpened her sight. Nathaniel Comfort's The Tangled Field calls that the McClintock Myth, argues she was well regarded by her peers from early on, and says she helped build the legend herself. Newer work says she left Missouri mainly because she had stopped trusting the administration.

Molecular biology came round. Jacob and Monod described genetic regulation in bacteria in 1961, transposition turned up in bacteria, yeast and phage by the end of that decade, and Activator and Dissociation were cloned. She took the National Medal of Science in 1970 and the first MacArthur fellowship in 1981. The 1983 Nobel in Physiology or Medicine came to her alone, the first unshared science Nobel awarded to an American woman. She never married, stayed at Cold Spring Harbor as scientist emerita, and died of natural causes at Huntington on September 2, 1992, at 90. The Postal Service put her on a 2005 stamp with Feynman, Gibbs and von Neumann. In 2024 a plant from Kerala was named for her.

Barbara McClintock's life against the full span of the corpus.

• A Correlation of Cytological and Genetical Crossing-Over in Zea Mays article
  With Harriet Creighton - the microscopic proof that crossover and recombination are one event 1931
• Neurospora I. Preliminary Observations of the Chromosomes of Neurospora crassa article
  Two months at Stanford settled the cytology of the mould 1945
• The Origin and Behavior of Mutable Loci in Maize article
  The paper announcing Dissociation and Activator 1950
• Induction of Instability at Selected Loci in Maize article
  The full statistical case, and the last detailed account of controlling elements she published 1953
• Chromosome Constitution of Races of Maize book
  With Kato and Blumenschein, out of the Latin American maize survey she began in 1957 1981
• The Significance of Responses of the Genome to Challenge article
  Her Nobel lecture, printed in Science 1984

• 1908 aged ~6 The family settles in Brooklyn She had already spent years there with an aunt and uncle to ease her parents' finances.
• 1919 aged ~17 Registers at Cornell's College of Agriculture over her mother's objection Her father allowed it just before registration closed.
• 1927 aged ~25 Takes her PhD at Cornell
• 1931 aged ~29 Publishes the crossing-over paper with Harriet Creighton
• 1941 aged ~39 Leaves the University of Missouri By December she had a temporary post at Cold Spring Harbor. She stayed for life.
• 1944 aged ~42 Elected to the National Academy of Sciences, the third woman
• Summer 1944 aged ~42 Begins the mottled-kernel experiments that led to transposable elements
• 1951 aged ~49 Presents controlling elements at the Cold Spring Harbor symposium
• 1983 aged ~81 Awarded the Nobel Prize in Physiology or Medicine, unshared

• George Beadle 1903–1989
  Geneticist who won the Nobel Prize for showing that genes control biochemical reactions in cells. in the Cornell maize group with her
• James Watson 1928–2025
  Co-discoverer of the DNA double helix structure, earning a Nobel Prize in Physiology or Medicine. ran the laboratory where she worked
• Richard Feynman 1918–1988
  Theoretical physicist known for his work in quantum mechanics and his accessible teaching style. shared her 2005 American Scientists stamp
• John von Neumann 1903–1957
  Hungarian-American mathematician and engineer whose computer architecture remains the basis of modern computing. shared her 2005 American Scientists stamp
• Rachel Carson 1907–1964
  Marine biologist whose book Silent Spring launched the modern environmental movement. the other woman who made her case against the field