The purpose of this study was to examine the use of a tool-set by capu
chin monkeys (Cebus apella). Capuchins were presented with an apparatu
s designed to accommodate the use of pounding tools to crack walnuts a
nd the use of probing tools to loosen and extract the inner meat. Thre
e capuchins used stones and sticks sequentially for these purposes. Th
e capuchins' behavior was similar in form and function to behavior tha
t has been reported for chimpanzees in analogous situations. These res
ults provide further evidence of the extensive tool-using capabilities
of capuchin monkeys and are consistent with a hypothesis of cross-spe
cies continuity in the skillful use of tools by primates.