Three requirements of evolution are persistence with change, internally cohesive individuals of limited duration, and interaction with environment. We recast these properties in megaevolutionary terms. Homologous structures persist over geological time as they evolve in form and function. Species, which arise through a greater or lesser genetic revolution, behave as individuals. The interaction of genes and environments--development--underlies both the origin of species and the continuity of homologies. The properties of epigenetics--self assembly , feedback, alternative pathways to the same developmental end, compensation for the inevitable irregularities of development--allow a redefinition of genetic revolution in terms of the establishment of new, stable developmental patterns: a typological result produced in acceptably populational ways. Homologues, similarly, are the products of evolving epigenetic sub-systems. Although developmental systems retain ancestral potentials that remain unexpressed for tens of millions of years, such potentials are so burdened with other developmental pathways built upon them that they hold little promise for evolutionary change. But where a recent developmental change has occurred, no such "buffering" exists. As errors occur, some will be epigenetically accommdated and, if adaptive, genetically assimilated. *These are the quanta of evolution.* If a recent adaptive breakthrough has occurred, it will be "supported" at first by interacting epigenetic sub-systems. The poorly canalized epigenetic system most closely associated with the new adaptation will be under intense selection to build up an epigenetic environment that assures the predictable expression of the new trait. Until this happens, further "experiments" along the lines of the initial change can occur and be assimilated. Depending on ecological milieu, this is the stuff of adaptive radiation , evolutionary trends, or allometric change. Speciation, which can occur without any adaptive change, is the result of analogous changes in the epigenetic systems responsible for mate recognition. We accept the neo-Darwinian reliance on natural selection acting in populations. But we choose to concentrate on its action on developmental processes, rather than on traits, the obvious and experimentally tractable end-products of such processes. The normal features of epigenetics fortuitously lay down the lines of least resistance to evolutionary change. We find ourselves looking at an intrinsic and emergent side to evolution, a view that in the past was held, on similar general grounds, by Bateson, Goldschnidt, and Waddington. The story of evolution is perhaps less the warfare of selfish genes than the working out of the potentials of selfless epigenes.
