Complex battlefields favor strong soldiers over large armies in social animal warfare

Warfare is fundamental to the outcome of competition in social species from humans to insects and is of global interest and appeal to scientific and public audiences alike. Although theory predicts that the environment in which group battles take place will affect the optimal strategy, empirical tests are difficult. Here, we use simulated battles in a gaming construct to demonstrate that investing in smaller armies of stronger soldiers is more effective in complex battlefields. We then use a real-world system for group battle studies—social ants—to validate our findings in an empirical setting and find that small armies of large ants perform better against large armies of small ants in complex environments.