Theory of cellular homochirality and trait evolution in flocking systems

TL;DR

This paper presents a model combining collective behavior and molecular chirality theories to explore how cellular homochirality can emerge from symmetric states without explicit symmetry-breaking mechanisms, influenced by system openness and noise.

Contribution

It introduces a novel integrated model linking flocking dynamics with molecular homochirality to explain the emergence of cellular homochirality.

Findings

Homochirality can emerge from symmetric states without explicit symmetry-breaking.

System openness and noise are critical factors in reaching homochirality.

The model applies broadly to trait evolution in flocking and multi-species systems.

Abstract

Chirality is a feature of many biological systems and much research has been focused on understanding the origin and implications of this property. Famously, sugars and amino acids found in nature are homochiral, i.e., chiral symmetry is broken and only one of the two possible chiral states is ever observed. Certain types of cells show chiral behavior, too. Understanding the origin of cellular chirality and its effect on tissues and cellular dynamics is still an open problem and subject to much (recent) research, e.g., in the context of drosophila morphogenesis. Here, we develop a simple model to describe the possible origin of homochirality in cells. Combining the Vicsek model for collective behavior with the model of Jafarpour et al., developed to describe the emergence of molecular homochirality, we investigate how a homochiral state might have evolved in cells from an initially symmetric state without any mechanisms that explicitly break chiral symmetry. We investigate the transition to homochirality and show how the "openness" of the system as well as noise determine if and when a globally homochiral state is reached. We discuss how our model can be applied to the evolution of traits in flocking systems in general, or to study systems consisting of multiple interacting species.