Socially tolerant lions (Panthera leo) solve a novel cooperative problem.

Cooperative interactions vary in complexity. The emotional reactivity hypothesis posits that cooperative complexity is constrained by social intolerance. Relaxed social constraints should thereby increase cooperative flexibility and have been proposed as a key step in cognitive evolution. Lions (Panthera leo) are an ideal candidate for investigating cooperative complexity and tolerance. Lions regularly cooperate and their egalitarian social structure predicts high social tolerance. I used a food-sharing task and cooperative problem-solving task to investigate tolerance and cooperation in lions. The majority of pairs (N = 5/7 dyads) solved the cooperative task, repeated success in consecutive trials, and demonstrated cooperative complexity at the levels of similarity and synchrony. Surprisingly, lions showed no evidence of coordination. If coordination occurred, then after gaining experience and when no longer naïve to the need for a partner, lions should increase the proportion of time spent together and preferentially attended to the task in the presence of a partner. However, naïve and experienced pairs did not differ (Wilcoxon matched-pair signed-rank test: both present at apparatus: S4 = - 4.5, N = 5, p = 0.50 |both touching the rope: S4 = - 3.5, N = 5, p = 0.43| simultaneous action: S4 = 2.5, N = 5, p = 0.63). As predicted, lions displayed high tolerance and cooperative success was positively correlated with tolerance (Spearman's correlation test: ρ = 0.83, N = 7, p = 0.02*). To date, this is the first experimental test of and support for cooperative problem solving in lions.