Evolutionary features in a minimal physical system: Diversity, selection, growth, inheritance, and adaptation.

We present a simple physical model that recapitulates several features of biological evolution, while being based only on thermally driven attachment and detachment of elementary building blocks. Through its dynamics, this model samples a large and diverse array of nonequilibrium steady states, both within and between independent trajectories. These dynamics exhibit directionality with a quantity that increases in time, selection, and preferential spatial expansion of particular states, as well as inheritance in the form of correlated compositions between successive states, and environment-dependent adaptation. The model challenges common conceptions regarding the requirements for life-like properties: It does not involve separate mechanisms for metabolism, replication, and compartmentalization; stores and transmits digital information without template replication or assembly of large molecules; exhibits selection both without and with reproduction; and undergoes growth without autocatalysis. As the model is based on generic physical principles, it is amenable to various experimental implementations.