whistling orangutan

Tool use and culture

Like the other great apes, orangutans are among the most intelligent primates.[12] Wild chimpanzees have been known to use tools since the 1960s.[13] Tool use in orangutans has been observed in ex-captive populations.[14]

Evidence of sophisticated tool manufacture and use in the wild was reported from a population of orangutans in Suaq Balimbing (Pongo pygmaeus abelii) in 1996.[15] These orangutans developed a tool kit for use in foraging that consisted of insect-extraction tools for use in the hollows of trees, and seed-extraction tools which were used in harvesting seeds from hard-husked fruit. The orangutans adjusted their tools according to the nature of the task at hand and preference was given to oral tool use.[16] This preference was also found in an experimental study of captive orangutans (P. pygmaeus).[17]

Carel P. van Schaik from the University of Zurich and Cheryl D. Knott from Harvard University further investigated tool use in different wild orangutan populations. They compared geographic variations in tool use related to the processing of Neesia fruit. The orangutans of Suaq Balimbing (P. abelii) were found to be avid users of insect and seed-extraction tools when compared to other wild orangutans.[18][19] The scientists suggested that these differences are cultural. The orangutans at Suaq Balimbing live in dense groups and are socially tolerant; this creates good conditions for social transmission.[18] Further evidence that highly social orangutans are more likely to exhibit cultural behaviors came from a study of leaf-carrying behaviors of ex-captive orangutans that were being rehabilitated on the island of Kaja in Borneo.[20] The above evidence is consistent with the existence of orangutan culture as geographically distinct behavioral variants which are maintained and transmitted in a population through social learning