Trade-offs between social learning and individual innovativeness in common marmosets, Callithrix jacchus

Social learning and innovation are two different ways to acquire novel behaviours, and the form of the relationship between these two processes strongly affects cultural evolution. Whereas modelling results suggest a negative correlation between the two processes within a species, comparative data show, and the cultural intelligence hypothesis predicts, positive covariation across species. Thus, there is considerable uncertainty about the form of the relationship between social learning and innovation. We explored this problem experimentally in common marmosets. Social learning of 18 subjects was assessed by presenting a video clip of a conspecific demonstrator solving a complex foraging task and comparing their success to a control group. For the same subjects, the propensity to innovate was assessed with two tasks that operationalize different types of innovation: (1) a multistage problem-solving task to estimate goal-directed Type I innovation, that is, the ability to find a solution to a novel problem or a novel solution to an old problem, and (2) a flexibility task testing for more incidental Type II innovation, that is, the propensity to realize and switch to a novel, but easier solution after the establishment of a well-learned solution. Social learning was negatively correlated with Type II innovation, but not with Type I innovation. We discuss these results with regard to competition within an individual of the various attentional processes aimed at conspecifics' behaviour or aspects of the environment, and whether they might be the result of the cooperative breeding system shared by humans and callitrichids.