The social learning of tool use by orangutans (Pongo pygmaeus)

Abstract

Very little is known about the social learning of orangutans (Pongo pygmaeus), especially in the context of problem-solving situations such as tool use. Sixteen orangutans were presented with a rake-like tool and desirable but out-of-reach food. Eight subjects observed a human demonstrator use the tool in one way, while another eight observed the demonstrator use the tool in another way. Subjects behaved identically in the two experimental conditions, showing no effect of the type of demonstration observed. Analysis of individual learning curves suggested that a large component of individual trial-and-error learning was at work, even for two subjects who received additional trials with an orangutan demonstrator. This pattern of results suggests that subjects were paying attention to the general functional relations in the task and to the results obtained by the demonstrator, but not to the actual methods of tool use demonstrated. It is concluded that subjects in both conditions were employing emulation learning, not imitative learning.