Processing of novel food reveal payoff and rank-biased social learning in a wild primate

Cultural complexity is strongly shaped by the efficiency by which new knowledge is propagated. Different social learning strategies (SLS), where individuals biasedly learn particular behaviors or from specific demonstrators, can contribute to an individual’s success. While SLS have been mostly studied in isolation, their interaction and the interplay between individual and social learning is less understood. We performed a field-based open diffusion experiment in a wild primate. We provided two groups of vervet monkeys with a novel food, unshelled peanuts, and documented how three different peanut opening techniques spread within the groups. We analyzed data using hierarchical Bayesian dynamic learning models that explore the integration of multiple SLS with individual learning. We show that vervets preferentially use the technique yielding the highest observed payoff, and also bias attention toward individuals of higher rank. This shows that traditions may arise when individuals integrate information about the efficiency of a behavior alongside cues related to the rank of a demonstrator.