The intermediate social resilience hypothesis: a testable framework linking animal sociality to population resilience under environmental change

Sociality can improve access to information, cooperation, collective defense, parental care, collective decision-making, and social buffering, but it can also intensify competition and pathogen transmission, spread outdated information, and create dependence on particular partners, roles, or traditions. In this article, we propose the Intermediate Social Resilience Hypothesis (ISRH), which predicts that, under specified conditions, population resilience may be greatest at an intermediate value of a defined social dimension. We do not rank all animal societies on a single universal scale. Instead, low, intermediate, and high values must be defined within a measurable dimension, such as group size, cohesion, network connectivity, cooperative effort, or reliance on social information, and within a biologically comparable system. Resilience must likewise be specified as resistance, recovery, temporal stability, or persistence under a defined form and scale of environmental change. The distinctive contribution of the ISRH is not simply the recognition that sociality can generate both benefits and costs, but the explicit prediction that their balance can, under identifiable conditions, produce a testable intermediate maximum in population resilience. An intermediate optimum is expected only when social benefits initially increase but eventually saturate, whereas one or more relevant social costs continue to rise. Environmental harshness, variability, unpredictability, and the flexibility, modularity, redundancy, or multilevel organization of social systems may shift, flatten, or eliminate this relationship. The hypothesis generates two falsifiable predictions that can be tested through comparative, longitudinal, experimental, phylogenetic, network, and population-monitoring approaches. By integrating behavioral ecology, social evolution, resilience theory, and conservation, the framework explicitly recognizes the multidimensional nature of animal social systems while providing explicit criteria for distinguishing support for the ISRH from monotonic, threshold, flat, or context-dependent alternative relationships.