Physical strength predicts political violence

Research has revealed an association between individual physical strength and attitudinal support for modern war. Physical strength of one individual has an infinitesimal effect on the outcomes of state-level aggression involving large-scale armies and complex military technology. The fact that stronger individuals do support such aggression hints at an evolved psychology specialized for small-scale coalitional aggression, where strength of coalition members non-negligibly contribute to the net coalition strength. Here, I examined whether strength also accounts for participation in modern political aggression, as contrasted to mere support. Given that contemporary political aggression primarily occurs within—not between—states, I focused on intra-state forms of political violence, specifically violent antigovernment protests. To enhance external and ecological validity, I relied on large probability samples from both non-WEIRD and WEIRD countries experiencing political violence (N = 6283; interviewees were quota-sampled from YouGov online panels to generate representative samples of online adult populations). Multinational analyses revealed that self-perceived strength significantly predicts intentions to participate in political violence and self-reported participation, and that this association is stronger among young interviewees, but not among men (compared to women). The predictive power of strength was modest but comparable to that of gender, an established predictor of aggression. I discuss why the fact that strength—a physiological variable—relates to political violence—a complex modern phenomenon—is remarkable. Subsequently, I suggest a new research agenda that draws on insights from evolutionary research to study modern political violence.