Barbara McClintock won the 1983 Nobel Prize in Physiology or Medicine for discovering mobile genetic elements.
Working with maize, McClintock found that certain DNA segments could change position within the genome. She called the controlling elements Activator and Dissociation, showing that they could influence whether nearby genes were switched on or off.
Her findings were presented in the 1940s and 1950s, when many scientists expected genes to occupy fixed locations. The broader importance of transposable elements became clear decades later, when similar sequences were identified throughout plants, animals and microorganisms.
McClintock received the 1983 prize alone, an unusual distinction in Nobel science. Her work is sometimes called the discovery of “jumping genes,” though that phrase is informal. Transposons can affect genome structure, mutation and gene regulation, but they do not literally move as independent organisms.