Evidence is mounting for the idea that living systems sit close to a critical point. But what if the social behaviour of monkeys was also influenced by criticality? Bryan Daniels and colleagues sought to find out, by examining the distribution of fight sizes in a population of pigtailed macaques (Macaca nemestrina; pictured). They found signs that these primates indeed hover near a tipping point, trading robustness for the adaptability associated with criticality. But more surprising, perhaps, was the indication that they may actively tune their distance from criticality by exploiting the group's heterogeneity.
Daniels et al. looked at fight sizes from a group of 48 monkeys, introducing an operational definition of criticality for finite systems based on the Fisher information and a collective instability measure. They found that the monkeys with the greatest sway over average fight sizes could tune the group's distance from the critical point by adjusting their own behaviour. How well these ideas map to us higher primates remains to be seen.
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Klopper, A. Critical behaviour: Monkey business. Nature Phys 13, 205 (2017). https://doi.org/10.1038/nphys4063