Origins of life: An operational definition

Two very different models are used for the scientific study of life's origins: in the Troland-Muller model, life is molecular and its defining characteristic is gene function; in the Oparin-Haldane model, life is cellular and its defining characteristic is metabolic function. While each of these models implicitly defines the living, neither provides criteria by which theemergence of life could be recognized in the laboratory.Anoperational definition of the living makes explicit the system logic of metabolic self-production: (1) that whatever form it may take, life is a function of its biochemical processes; (2) that no single biochemical process has integrity apart from an entire network of processes; (3) that a network of processes can have continuity only by being enclosed within a boundary structure, i.e., by the selective partition of a microenvironment as a domain for the bioenergetic-biosynthetic network; and (4) that life is a single phenomenon, distinct in its continuity of capture and storage of energy in such networks, driving the processes that produce its material constituents.This paper presentsautopoiesis as life-defining and discusses the utility of its criteria in our search for the origins of life on Earth. Enactment of the autopoietic criteria would result in aminimal cell and would demonstrate the experimental recapitulation of life's Archaean origins.