Triggers of phase transitions among termite collective behaviours

Determine the causal mechanisms and conditions that trigger transitions among the three emergent collective behaviours—disorder, clustering, and milling—observed in groups of Cornitermes cumulans termite workers confined within circular arenas, including the role of density, velocity, alignment, and collisions as potential drivers of these phase changes.

Background

The paper identifies three dynamical phases in confined groups of Cornitermes cumulans termites: disorder, clustering, and milling. Using time-series analyses, order parameters, and scaling measures (e.g., Hurst exponent, angular momentum, and turning angle variance), the authors characterize these phases and observe transitions between them.

Despite this quantitative characterization, the causal factors and mechanisms that initiate transitions among these phases are not established. The authors note candidate factors such as density, velocity, alignment, and collisions, but explicitly state that explanations for what triggers these transitions remain unknown, highlighting an open question central to understanding collective behaviour in active matter systems.