title: Marginal stability in chemical systems and its relevance in the origin of life.
abstract: Concentration fluctuations are always present in solutions; it has been noticed that, in chemical systems, they can lead to deviations from what is expected from mass-action equations. I recently described the class of the "marginally stable" chemical systems; namely, a system that have an infinity of stationary states forming a continuous curve, and I showed that they present such deviations, which appear as a drift along the stationary-state curve [Phys. Rev. Lett. 105, 058102 (2010)]. Here I describe various marginally stable chemical reaction networks, including replicating molecules, and I present numerical calculations based on reaction-diffusion master equations, showing that the thermodynamic fluctuations induce a drift. This drift can be interpreted in terms of evolution toward a more efficiently replicating system and is analogous to a Darwinian evolution. The concentration fluctuations observed during the drift are scale invariant. Relevance of this phenomenon to the origin of life is discussed. I propose that marginal stability is the mathematical property defining chemical reaction networks potentially involved in the origin of life.
authors: Dipartimento di Medicina Sperimentale, Università degli Studi di Milano, Bicocca Via Cadore 48, Monza (MI) I-20052, Italy. dbrogioli@gmail.com
authors: Doriano
authors: D
authors: Brogioli
mesh_terms: D003198:Computer Simulation; D008956:Models, Chemical; D008958:Models, Molecular; D000069497:Origin of Life