Manual skills for processing plant underground storage organs by wild bearded capuchins.

Despite having smaller body-mass and greater manual constraints than catarrhine extractive foragers, capuchins, even smaller individuals, mastered USO processing thanks to their behavioral flexibility and persistence. Our findings reveal that precision grips are not essential for forceful actions during complex food processing and that, unlike catarrhines, capuchins, especially adults, rarely use thumb opposition during forceful grasping of food. In contrast, extended sustained attention and varied manual behavior appear to be convergent features of platyrrhine and catarrhine extractive foragers.