Variation in cultural attitude, knowledge and individual motivational factors impact engagement and tool use in a field experiment in wild chimpanzees

Abstract

Cultural traditions shape how animals approach and solve problems. Previously, Ugandan chimpanzees (Pan trogodytes schweinfurthii), have engaged with the honey-trap experiment, an apparatus designed to mimic a beehive and provide ecological opportunities for tool use, relying on their cultural knowledge. Here, we presented chimpanzees from the Mwera South community, a newly habituated community in Bugoma Forest, with variations of the honey-trap experiment and compared their engagement to other Ugandan chimpanzee communities to investigate various aspects of cultural behaviour in animals. First, we wanted to test whether communities varied in cultural attitude towards a given food, and whether this attitude correlated with particular instrumental components of their cultural knowledge. Second, we were interested in analyzing individual variation across individuals within the same culture. Comparing individuals from Bugomas Mwera South (N=15), Budongos Sonso (N=34), and Kibales Kanyawara (N=14) communities, we found that the latter both exhibited higher engagement with the honey-trap, and a dedicated instrumental method, stick use, to obtain the honey. In contrast, Sonso and Mwera South chimpanzees appeared similar in lacking a cultural attitude towards honey, with no attached tool technique overall. Nevertheless, there were also strong inter-individual differences. Notably, some Mwera South chimpanzees displayed undescribed behavioural flexibility, using a range of tool behaviours including both stick and leaf tool use --a pattern never before documented in over a decade of honey-trap experiments. These results demonstrate that cultural attitudes toward resources constitute an additional layer to culture in addition to instrumental knowledge, and that the latter two coexist with individual motivational traits in influencing the realization of cultural behaviour.