An equation of state for insect swarms

Abstract

Collective behaviour in flocks, crowds, and swarms occurs throughout the biological world. Animal groups are generally assumed to be evolutionarily adapted to robustly achieve particular functions, so there is widespread interest in exploiting collective behaviour for bio-inspired engineering. However, this requires understanding the precise properties and function of groups, which remains a challenge. Here, we demonstrate that collective groups can be described in a thermodynamic framework. We define an appropriate set of state variables and extract an equation of state for laboratory midge swarms. We then drive swarms through “thermodynamic” cycles via external stimuli, and show that our equation of state holds throughout. Our findings demonstrate a new way of precisely quantifying the nature of collective groups and provide a cornerstone for potential future engineering design.

Flying honeybees adjust their reaction times to enable group cohesion

“…An individual agent’s influence on swarms is posed using zone based models and communication topological analysis indicates that the attraction and alignment weights affects the group behavior and structure [45]. The swarm’s collective behavior can also be described by elastic or thermodynamic analogies where external stimulus can represent the midge swarm behavior [46]. Despite the availability of rigorous proofs for sufficiency of velocity alignment (e.g.…”

Spaces between insects in laboratory swarms move like insects in natural swarms

“…The identification and understanding of these emergent macroscopic properties of insect swarms holds promise of a unified "thermodynamic" theory of insect swarms, where one seeks to describe their mechanical-like properties in a way that does not directly reference individual behaviours [19]. The duality established here suggests that many of the emergent mechanical/thermodynamic properties of laboratory swarms will be present in some form in wild swarms [14,20,21]. Moreover it suggests that theoretical insights into laboratory swarms (which are relatively easy to obtain because long-range interactions are absent [4][5][6]) can be carried over to natural swarms which are strongly correlated [6,12,13,[22][23][24].…”

“…The duality established here between laboratory and natural swarms bolsters the approach to collective behaviour championed by Ouellette [9,19] who recognized that the properties of animal aggregates cannot be determined by passive observation alone; instead one must interact with them, by for example applying controlled perturbations. This approach allows for the extraction of emergent group properties that are not directly linked to the characteristics of the individuals [20,21]. The identification and understanding of these emergent macroscopic properties of insect swarms holds promise of a unified "thermodynamic" theory of insect swarms, where one seeks to describe their mechanical-like properties in a way that does not directly reference individual behaviours [19].…”

Insect visuomotor delay adjustments in group flight support swarm cohesion

“…An individual agent’s influence on swarms is posed using zone based models and communication topological analysis indicates that the attraction and alignment weights affects the group behavior and structure 42 . The swarm’s collective behavior can also be described by elastic or thermodynamic analogies where external stimulus can represent the midge swarm behavior 43 . Despite the availability of rigorous proofs for sufficiency of velocity alignment (e.g.…”