Punctuated Chirality

TL;DR

This paper proposes that environmental events can induce the emergence of homochirality in prebiotic chemistry through a process of punctuated symmetry breaking, offering a new explanation for life's molecular asymmetry.

Contribution

It introduces a model linking environmental fluctuations to chiral symmetry breaking, extending punctuated equilibrium concepts to the origin of biological homochirality.

Findings

Environmental events can drive achiral conditions towards chirality.

Long-duration, high-intensity events are key to symmetry breaking.

Homochirality likely resulted from sequential environmental triggers.

Abstract

Most biomolecules occur in mirror, or chiral, images of each other. However, life is homochiral: proteins contain almost exclusively levorotatory (L) amino acids, while only dextrorotatory (R) sugars appear in RNA and DNA. The mechanism behind this fundamental asymmetry of life remains an open problem. Coupling the spatiotemporal evolution of a general autocatalytic polymerization reaction network to external environmental effects, we show through a detailed statistical analysis that high intensity and long duration events may drive achiral initial conditions towards chirality. We argue that life's homochirality resulted from sequential chiral symmetry breaking triggered by environmental events, thus extending the theory of punctuated equilibrium to the prebiotic realm. Applying our arguments to other potentially life-bearing planetary platforms, we predict that a statistically representative sampling will be racemic on average.