Tool use and complex object manipulation skills are of intense interest to many disciplines. Yet the number of nonhuman primate taxa exploited in these comparative studies is usually limited to the great apes, and especially the chimpanzee, Pan troglodytes. The focus on chimpanzees is understandable. In the wild, chimpanzees greatly exceed all other apes in the frequency and complexity of tool manufacture and object and tool use (Sugiyama, 1997; Whiten et al., 1999). In captivity, however, tool use and complex object manipulation is common and can be readily elicited from all great ape species (Visalberghi et al., 1995).
In recent years, primatologists and comparative psychologists have paid increasing attention to the manipulative skills of capuchins, the New World primate genus Cebus. Not only does the proclivity of capuchins to use tools surpass that of all other monkeys either in the Old or the New World, but in many respects the spontaneous manipulative activities and dexterity of capuchins and chimpanzees share many characteristics (Anderson, 1996; Antinucci and Visalberghi, 1986; Panger, 1998; Parker and Gibson, 1977). Capuchins are well known for strenuous arthropod-extraction techniques and complex manipulation of difficult to process fruits (Fragaszy and Boinski, 1995; Janson and Boinski, 1992). Pounding and rubbing of fruits, invertebrates, and other food items against hard substrates is another food-processing technique exhibited by all four capuchin species (C. apella, brown capuchin, in Colombia and Peru: Izawa and Mizuno, 1977; Struhsaker and Leland, 1977; Terborgh, 1983; C. albifrons, white-fronted capuchin in Peru: Terborgh, 1983; C. capucinus, white-faced capuchin, in Costa Rica: Panger, 1998; Rose, 2001; and C. olivaceus, wedge-capped capuchin, in Venezuela: Fragaszy and Boinski, 1995; Robinson, 1986).