Manipulative abilities during the same tool use task in different species of primates
Résumé
Primates have highly developed abilities for grasping and manipulation that differ between
species. In this context, the human hand is considered unique, based on its functional characteristics. However, the real dynamic manual abilities of primates remain poorly known. The purpose of this study is to compare the manipulative strategies in different species of primates (humans, chimpanzees, gorillas, orangutans, capuchins), during the same tool use task. This task requires the use of a tool to recover a static food item in a wooden maze while facing many obstacles; the wire netting between the subject and the maze, and the obstacles inside the maze. All species were in the same experimental conditions allowing us to compare across species. We here focus on the functional strategies used during this task by the different species and quantify the grip types and the in-hand movements involved to reposition the tool in the hand. We found common strategies despite the differences in hand morphology but also strategies specific to some species. We discuss the results in the context of the evolution of manipulative behaviours and highlight the importance of novel methods to understand better the manual specificities of each species. This study complies with the ethical guidelines by the CNRS and French governmental animal care committees and with the IPS Guidelines for the Use of Nonhuman Primates in Research.