Files
Abstract
The ability to manipulate objects within the hand has been fully described in humans but remains to be documented and described in non-human primates. Studies suggest that several non-human primates are capable of such movements, evidenced by the dexterity of precision handling seen in the foraging and grooming behaviors of Old World primates and Cebus monkeys. Laboratory studies looking at individual control of the digits and neuroanatomy have supported this implication. This study presented a task to elicit in-hand movements in three adult chimpanzees (Pan troglodytes) and six adult capuchin monkeys (Cebus apella). All of the chimpanzees and two of the capuchins performed in-hand movements; the chimpanzees performed a wider variety of these movements and at a higher rate. The chimpanzees thus demonstrated more sophisticated control and coordination of the digits than the capuchins. The findings suggest behavioral consequences of the muscular, skeletal, and neuroanatomical features of each species.