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Wild bearded capuchins (Cebus libidinosus, quadrupedal, medium-sized monkeys) crack nuts using large stones. We examined the kinematics and energetics of the nut-cracking action of two adult males and two adult females. From a bipedal stance, the monkeys raised a heavy hammer stone (1.46 and 1.32 kg, from 33 to 77% of their body weight) to an average height of 0.33 m, 60% of body length. Then, they rapidly lowered the stone by flexing the lower extremities and the trunk until the stone contacted the nut. A hit consisting of an upward phase and a downward phase averaged 0.74 s in duration. The upward phase lasted 69% of hit duration. All subjects added discernable energy to the stone in the downward phase. The monkeys exhibited individualized kinematic strategies, similar to those of human weight lifters. Capuchins illustrate that human-like bipedal stance and large body size are unnecessary to break tough objects from a bipedal position. The phenomenon of bipedal nut-cracking by capuchins provides a new comparative reference point for discussions of percussive tool use and bipedality in primates. KEY WORDS tool use; percussion; upright stance; nonhuman primate

Chimpanzees and capuchins demonstrate greater varieties and higher rates of tool-use when compared to other non-human primates. Although capuchins have been studied extensively in captivity, data on their tool-using behavior under free-ranging conditions are limited. This is the first long-term field research to systematically study complex object manipulation in capuchins. The aims of this research are 1) to examine the types, rates, and contexts of tool- and object-use in free-ranging capuchins and 2) to determine if free-ranging capuchins' object manipulation behavior is comparable to the behavior exhibited by captive individuals. Data on 3 troops of white-faced capuchins (Cebus capucinus) were collected from February 1995 to January 1996 at Palo Verde, Costa Rica. Data were collected using focal animal and ad libitum sampling techniques. Any observed incident of tool-use and object-use was recorded. No tool-use was observed during the 11-month study. Object-use (pound, rub, and fulcrum-use) occurred at a rate of 0.19/hr and made up less than 1% of the monkeys' time (there were no differences among the age/sex classes). The results indicate that free-ranging capuchins do not exhibit the range of tool-using behavior demonstrated by their captive counterparts. This may be the result of differential motivational responses to objects, arboreal lifestyle, absence of adequate tool material, and/or absence of food resources that require extraction involving tool-use. KEY WORDS primates; tool-use; object manipulation; extractive foraging

For comparative purposes, culture can be defined as socially transmitted behavioral innovations. Orangutan tool use has earlier been shown to exhibit critical features of culture: all-or-nothing distribution across sites, stability, and loss across a dispersal barrier. Using the Whiten et al. (1999, Nature 399: 682) heuristic criteria for recognizing culture from geographic distributions of behavioral variants, the orangutan research community has so far recognized 24 putative cultural elements. Hence, orangutans have similar cultural variation to that found in chimpanzees, implying that the capacity for great-ape cultures, including material culture, is at least 14 My old. In addition, we could use these data to test for the existence of properties of cultural systems, as in humans, and these tests were successful. However, because culture, as defined above, may be more common among animals, we need to distinguish between different kinds of culture, and develop a comparative study of culture that identifies the major evolutionary differences and their underlying mechanistic bases.