Although subsequent studies revealed sometimes baroque variations in eukaryotes, the operon remains the core theme (also the textbooks’ historical starting point) of gene regulation. Immediately following publication of the operon model, McClintock wrote an article for The American Naturalist on the parallels between the control systems in maize and bacteria1. For a time, she even referred to her elements as ‘operators’ and ‘regulators’. Jacob and Monod were not influenced by McClintock; when they referred to controlling elements, it was as extrachromosomal episomes, perhaps viral in origin, not as components of the cell’s normal regulatory machinery. McClintock, however, saw her work as the conceptual predecessor of the operon. Seven years later, in 1967, McClintock won the Kimber Medal, which was awarded to distinguished geneticists by the National Academy of Sciences each year from 1955 until 1970. McClintock had been on the short list since at least 1964. When the award was to be announced, Marcus Rhoades, the award committee chairman and McClintock’s closest colleague, asked Tracy Sonneborn, the geneticist best known for his investigations of cytoplasmic inheritance in Paramecium, to review the proposed press release. Sonneborn, familiar with McClintock’s interpretation, suggested inserting ‘that her studies of controlling systems of gene action were the precursors of the famous regulator–operon theory that won the Nobel Prize for its promulgators and that their thinking was probably much influenced by Barbara’s notion of twomember interacting controls’2. Although