In this paper delivered by Murray Gell-Mann at the Stony Brook Supergravity
Workshop in 1979, several paths to unification are discussed, from N=8
supergravity to SU5, SO10, and E6. Generalizations of SO10 to
spinor representations of larger groups are introduced. A natural mechanism for
generating tiny neutrino masses is proposed in the context of SO10, and
finally, focus on SU3 rather than SU2 or SO3 family symmetries is
noted.Comment: Retro-preprint of 1979 paper. Originally published in Supergravity,
P. van Nieuwenhuizen and D.Z. Freedman, eds, North Holland Publishing Co,
197