Gell-Mann was responsible, together with Pierre Ramond and Richard Slansky, and independently of Peter Minkowski, Rabindra Mohapatra, Goran Senjanović, Sheldon Lee Glashow, and Tsutomu Yanagida, for the seesaw theory of neutrino masses, that produces masses at the large scale in any theory with a right-handed neutrino. He is also known to have played a role in keeping string theory alive through the 1970s and early 1980s, supporting that line of research at a time when it was a topic of niche interest.