The Driving Force for Lifeʹs Emergence: Kinetic and Thermodynamic Considerations

The principles that govern the emergence of life from non-life remain a subject of intense debate. The evolutionary paradigm built up over the last 50 years, that argues that the evolutionary driving force is the Second Law of Thermodynamics, continues to be promoted by some, while severely criticized by others. If the thermodynamic drive toward ever-increasing entropy is not what drives the evolutionary process, then what does? In this paper, we analyse this long-standing question by building on Eigenʹs “replication first” model for lifeʹs emergence, and propose an alternative theoretical framework for understanding lifeʹs evolutionary driving force. Its essence is that life is a kinetic phenomenon that derives from the kinetic consequences of autocatalysis operating on specific biopolymeric systems, and this is demonstrably true at all stages of lifeʹs evolution — from primal to advanced life forms. Lifeʹs unique characteristics — its complexity, energy-gathering metabolic systems, teleonomic character, as well as its abundance and diversity, derive directly from the proposition that from a chemical perspective the replication reaction is an extreme expression of kinetic control, one in which thermodynamic requirements have evolved to play a supporting, rather than a directing, role. The analysis leads us to propose a new sub-division within chemistry — replicative chemistry. A striking consequence of this kinetic approach is that Darwinʹs principle of natural selection: that living things replicate, and therefore evolve, may be phrased more generally: that certain replicating things can evolve, and may therefore become living. This more general formulation appears to provide a simple conceptual link between animate and inanimate matter.