Can human social evolution be described in terms common to other sciences, most specifically, as an energy process? The Eighth Day reflects a conviction that the human trajectory, for all its uniqueness and indeterminism, will never be satisfactorily understood until it is framed in dynamics that are common to all of nature. The problem in doing this, however, lies in ourselves. The major social theories have failed to treat human social evolution as a component of broader natural processes. The Eighth Day argues that the energy process provides a basis for explaining, comparing, and measuring complex social evolution. Using traditional ecological energy flow studies as background, society is conceived as a self-organization of energy. This perspective enables Adams to analyze society in term of the natural selection of self-organizing energy forms and the trigger processes basic to it. Domestication, civilization, socioeconomic development, and the regulation of contemporary industrial nation-states serve to illustrate the approach. A principal aim is to explore the limitation that energy process imposes on human social evolution as well as to clarify the alternatives that it allows. Richly informed by contemporary anthropological historicism, sociobiology, and Marxism, The Eighth Day avoids simple reductionism and denies facile ideological categorization. Adams builds on work in nonequilibrium thermodynamics and theoretical biology and brings three decades of his own work to an analysis of human society that demands an extreme materialism in which human thought and action find a central place.