Gradualism (Evolutionary)

Gradualism is the doctrine, foundational to Darwinian evolution and the Modern Synthesis, that significant change occurs through the accumulation of small increments rather than through sudden transformations. Darwin insisted on gradualism as a methodological principle: if a proposed evolutionary transition could not be decomposed into a series of slight modifications, each conferring selective advantage, then the transition was suspect. The principle was powerful because it made evolution tractable — changes could be studied, intermediates could be predicted, the mechanism was comprehensible. But the principle was also a blindfold. Margulis demonstrated that the most consequential transitions in the history of life — from prokaryotes to eukaryotes, from non-photosynthetic to photosynthetic eukaryotes — were not gradual. They were mergers, discontinuous events producing qualitative novelty that gradualism cannot explain. The fossil record's gaps are not artifacts of poor preservation; they are evidence that some transitions genuinely were sudden, driven by mechanisms that do not operate incrementally.