Phase Transitions and Criticality in the Collective Behavior of Animals -- Self-organization and biological function

TL;DR

This paper reviews how animal groups exhibit phase transitions and operate near critical points, discussing the implications for collective computation and the challenges in applying physics concepts to biological systems.

Contribution

It synthesizes current research on phase transitions in animal collectives, emphasizing the importance of tuning near criticality rather than being exactly at it.

Findings

Animal groups exhibit phase transitions similar to physical systems.

Operating near criticality may optimize collective computation.

The focus is shifting from exact criticality to tunable proximity for functional benefits.

Abstract

Collective behaviors exhibited by animal groups, such as fish schools, bird flocks, or insect swarms are fascinating examples of self-organization in biology. Concepts and methods from statistical physics have been used to argue theoretically about the potential consequences of collective effects in such living systems. In particular, it has been proposed that such collective systems should operate close to a phase transition, specifically a (pseudo-)critical point, in order to optimize their capability for collective computation. In this chapter, we will first review relevant phase transitions exhibited by animal collectives, pointing out the difficulties of applying concepts from statistical physics to biological systems. Then we will discuss the current state of research on the "criticality hypothesis", including methods for how to measure distance from criticality and specific functional consequences for animal groups operating near a phase transition. We will highlight the emerging view that de-emphasizes the optimality of being exactly at a critical point and instead explores the potential benefits of living systems being able to tune to an optimal distance from criticality. We will close by laying out future challenges for studying collective behavior at the interface of physics and biology.