Cashew Nut Positioning during Stone Tool Use by Wild Bearded Capuchin Monkeys (Sapajus libidinosus)

Wild bearded capuchin monkeys (Sapajus libidinosus) at Serra da Capivara National Park, Brazil, employ two distinct techniques to position cashew nuts on an anvil before cracking them with stone tools. The arched position, previously undocumented, allows for more efficient nut-cracking by requiring less force than the traditional lateral positioning. This rare behavior was observed in only 6 out of 20 adult monkeys, suggesting it may require significant experience or social learning to master. Additionally, dry cashew nuts often needed preliminary processing to remove one lobe before being placed in an arched position, indicating a complex ontogeny. The study highlights the intricate tool-use behaviors exhibited by these primates and suggests further research is needed to fully understand the role of social learning in this technique.

Falótico, T., Luncz, L. V., Svensson, M. S., & Haslam, M. (2017). Cashew Nut Positioning during Stone Tool Use by Wild Bearded Capuchin Monkeys (Sapajus libidinosus). Folia Primatologica, 87(6), 392–397. https://doi.org/10.1159/000459621