Behavioral flexibility and its drivers in semi-urban vervet monkeys

Phylogenetic comparisons suggest that behavioral flexibility facilitates success in urban environments. It remains less clear whether urbanization fosters cognitive skills that require flexibility, or whether successful individuals in urban environments simply apply pre-evolved skills to solve new problems. To investigate whether variation in anthropogenic experience drives behavioral flexibility required to solve a new technical problem, we presented 42 semi-urban vervet monkeys (Chlorocebus pygerythrus) with a 3-phase foraging experiment. Each monkey's tendency to forage on human structures for food was measured to assess their exposure to human environments. We then used a sequential decision-tree-based probabilistic model to describe the series of monkeys' actions when attempting the task, quantifying 3 behavioral flexibility traits: switch tendency (shifting between known solutions between trials), innovativeness (ability to use unknown solutions), and learning sensitivity (ability to repeat known solutions). We found that individuals' switch tendency and innovativeness were not explained by anthropogenic experience and that the 3 traits were mostly unrelated to each other. Moreover, neither switch tendency, nor innovativeness predicted monkeys' human food consumption in this habitat. Thus, our study suggests that behavioral flexibility is not driven by anthropogenic foraging experience. Contrasting with the hypothesis that urbanization selects for behavioral flexibility, our findings instead imply that vervet monkeys already had sufficient behavioral flexibility and cognitive capacities to successfully exploit the urban habitat.