When Evolution is Revolution—Origins of Innovation

ABSTRACT: A pictorial tour of the theories of epochal evolution and structural complexity is presented with a view toward the dynamical origins, stabilization, and content of evolutionary innovations. A number of alternative explanations for the occurrence of long periods of stasis that are interrupted by sudden change have been proposed since the first days of mathematical evolutionary theory. Here contrasts are drawn between the mechanisms underlying epochal evolution and those implicated in the classical theory of stochastic intermittency (drift) due to Fisher, Wright's adaptive landscapes, Kimura's neutral evolution, and Gould and Eldredge's notion of punctuated equilibria. The comparisons suggest what a synthetic theory of the evolution of complexity might look like, while at the same time emphasizing that it will remain incomplete without a theory of biological structure. The computational mechanics theory of structural complexity is offered as an approach to the latter.