Major Evolutionary Transition

Maynard Smith and Szathmáry's term for the rare moments when formerly independent replicators become a larger entity that replicates only as a whole, with division of labor among the parts and a new medium of information storage and transmission. Agüera y Arcas treats every MET as symbiogenesis (bff exhibits all three criteria), extends the list past language to agrarian, urban and industrial transitions, and frames AI as the latest: a symbiosis of human and electronic predictors in which, for the first time, higher-order modeling leaves human skulls. Transitions accelerate because better predictors are better learners. Earlier entities persist — eukaryotes did not replace bacteria — which underwrites the book's anti-replacement optimism.