COOPERATIVE PROBLEM-SOLVING BY ORANGUTANS (PONGO-PYGMAEUS)

A captive pair of subadult male orangutans (Pongo pygmaeus) performed a cooperative task without training. Both partners had to pull a handl e simultaneously in order for each to get food. They also learned the importance of the partner at the apparatus to make a successful respon se. The requirements of the cooperative task appear to have been under stood by the orangutans, much like chimpanzees (Pan troglodytes) in th e same situation. In contrast, capuchins (Cebus apella) succeeded in t he cooperative task with a limited understanding of the requirement of the task and without faking into account the partner's role. These re sults gives further support to the hypothesis of a proximity of cognit ive processes between chimpanzees and orangutans (in contrast to monke ys) though orangutans have not been seen to hunt cooperatively in the wild.