CEES Friday seminar: Cultural transmission of tool selection in wild chimpanzees (Pan troglodytes verus)
By Lydia V. Luncz, University of Oxford, Oxford, UK
Diversity in percussive tool selection among neighboring chimpanzee (Pan troglodytes verus) communities has been shown to be group-specific and independent of ecological or genetic diversity. One of the most remarkable differences between groups is hammer selection during percussive nut-cracking in the Tai National Park in Côte d´Ivoire, West Africa. To crack open their main target nut, Coula edulis, they use wooden and stone hammers. Despite similar nut hardness and availability of raw materials in each groups’ territory, preference of tool material and tool size differs between groups. Interestingly, these group specific tool preferences remain stable and persist over time despite frequent female migration between groups. To investigate the underlying reasons for the establishment and maintenance of diversity between groups we studied the behavior of new immigrants. By recovering used tool remains at abandoned nut-cracking sites in the immigrants previous home range we reconstructed tool selection patterns of these females’ group prior to immigration. Comparing these patterns with direct observations after immigration, we demonstrate that new females were conforming to the tool selection pattern of their new community. Differences in the efficiency of tool properties suggest that these immigrants are exposed to costs or benefits in personal foraging success and adopt to tool norms despite personal knowledge of a more efficient foraging behaviour. Conformity is observed repeatedly during migrating events in chimpanzees, highlighting the importance of group belonging in wild animals.
Lydia V. Luncz
Leverhulme Early Career Fellow
Institute for Cognitive and Evolutionary Anthropology, University of Oxford, Oxford, UK