Spontaneous Emergence of a Metabolism

Abstract:

Networks of catalysed reactions with nonlinear feedback have been proposed to play an important role in the origin of life. We investigate this possibility in a polymer chemistry with catalysed cleavage and condensation reactions, studying the properties of a well-stirred reactor driven away from equilibrium by the flow of mass. Near equilibrium the distribution of material is uninteresting; it favours short polymers but is otherwise homogenous. However, under appropriate non-equilibrium conditions, the situation changes radically: The nonlinear feedback of the reaction network focuses the material of the system into a few specific polymer species, whose concentrations can be orders of magnitude about the background. Like a metabolism, the network of catalytic reactions "digests" the material of its environment, incorporating it into its own form. For this reason we call it an autocatalytic metabolism. We vary the diet of an autocatalytic metabolism, and demonstrate that under some variations it persists almost unchanged, while in other cases it dies. We argue that the dynamical stability of autocatalytic metabolisms gives them regenerative properties that allow them to repair themselves and to propagate through time.