On the emergence of autonomous chemical systems through dissipation kinetics
Résumé
This work describes the kinetic conditions under which dissipation can compensate for the entropic cost of self-organization and natural selection, thereby revealing a fundamental principle in biology. Sustaining an evolutionary process cannot be carried out for free, as it has an energy cost that must be covered by the system’s metabolism. Metabolic and evolutionary features of life cannot therefore be separated in an origin of life perspective. This role can be performed through the metabolic coupling of growth, self-organization, evolution and dissipation processes fueled by low-entropy energy harvested from the environment. The evolutionary process requires a reproduction cycle involving out-of-equilibrium intermediates and kinetic barriers that prevent the reproductive cycle from proceeding in reverse, as occurs within a simple autocatalytic cycle model. The analysis leads to the unexpectedly simple relationship that the system should be fed energy with a potential exceeding a value related to the ratio of the generation time to the transition state lifetime thereby enabling a process mimicking natural selection to take place. Reproducing life’s main features, in particular its Darwinian behavior, therefore requires satisfying particular constraints that relate time and energy. Simple models based on irreversible reaction cycles made only of unstable entities are shown to be able to reproduce some of these essential features in contrast to a chemistry based on stable building blocks, thereby offering a physical/chemical basis for the possible emergence of autonomous chemical systems.
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