Dynamic Self-organization in an Open Reaction Network: A Principle for the Emergence of Life

The emergence of life on Earth has attracted intense attention but remains unclear. A key problem is that the question of how living organisms can exhibit self-organizing ability that leads to highly ordered structures such as enzymes and DNA and high functions such as adaptive and evolutionary ability remains unanswered. This work reveals, by computer simulation and experiments, that a non-equilibrium steady state of an open reaction network (ORN), which is a good model of primitive life, demonstrates such self-organizing ability. Reaction and diffusion processes in an ORN are irreversible and always forced toward equilibrium and, hence, necessarily reach a steady state in which they have approached equilibrium to the largest extent possible and attained a full balance, if no oscillatory or dispersive behavior emerges. Thus, the steady state is firmly stabilized by the irreversible processes and is kept stable against fluctuation. As an ORN in general incessantly changes with time, this result can be interpreted as indicating that the steady state is produced by dynamic self-organization. The steady state can also exhibit adaptive ability because all the involved processes including inflows and outflows of chemical substances have attained a full balance and are in a harmonious state with the environment. Moreover, the steady state, which is in non-equilibrium, has a property of approaching equilibrium and thus can evolve toward highly ordered structures through interaction with the environment. In fact, we can argue that increases in the rate constants of reactions through the construction of highly ordered structures act as an important factor in an approach of a steady state to equilibrium. Thus, a steady state of an ORN can demonstrate multi-functional self-organizing ability essentially the same as that of living things and therefore dynamic self-organization in it can be regarded as providing a principle for the emergence of life.