Quenching to fix metastable states in models of prebiotic chemistry

TL;DR

This paper investigates how rapid environmental changes, like temperature quenches, can enhance the formation of metastable, lifelike chemical systems crucial for prebiotic evolution, using a computational model.

Contribution

It introduces a model demonstrating that rapid quenches can increase the likelihood of forming metastable, lifelike chemical states, providing a new perspective on prebiotic chemistry.

Findings

Rapid quenches increase metastable lifelike states

High temperature search phases may have occurred on early Earth

Effect depends strongly on the number of chemical monomers

Abstract

For prebiotic chemistry to succeed in producing a starting metastable, autocatalytic and reproducing system subject to evolutionary selection it must satisfy at least two apparently contradictory requirements: Because such systems are rare, a search among vast numbers of molecular combinations must take place naturally, requiring rapid rearrangement and breaking of covalent bonds. But once a relevant system is found, such rapid disruption and rearrangement would be very likely to destroy the system before much evolution could take place. In this paper we explore the possibility, using a model developed previously, that the search process could occur under different environmental conditions than the subsequent fixation and growth of a lifelike chemical system. We use the example of a rapid change in temperature to illustrate the effect and refer to the rapid change as a `quench' borrowing terminology from study of the physics and chemistry of glass formation. The model study shows that interrupting a high temperature nonequilibrium state with a rapid quench to lower temperatures can substantially increase the probability of producing a chemical state with lifelike characteristics of nonequilibrium metastability, internal dynamics and exponential population growth in time. Previously published data on the length distributions of proteomes of prokaryotes may be consistent with such an idea and suggest a prebiotic high temperature `search' phase near the boiling point of water. A rapid change in pH could have a similar effect. We discuss possible scenarios on early earth which might have allowed frequent quenches of the sort considered here to have occurred. The models show a strong dependence of the effect on the number of chemical monomers available for bond formation.