Orangutans can calculate reciprocity

Biologists from the University of St. Andrews report that orangutans are capable of exchanging tokens to acquire food for each other. The discovery is being hailed as the first demonstration of "calculated reciprocity" in non-human primates.

The most revealing experiments were conducted on two orangutans, Bim and Dok, in Germany. On prompting by the experimenters, the animals were able to register that they could exchange specific tokens to gain bananas for themselves and different tokens to gain bananas for their partner.

Dok, the female, proved more compassionate, willing to get Bim several bananas though his repeated prodding must have helped. Bim was more reluctant to be gallant but as time passed he saw value in keeping up his part of the bargain.

Interestingly, chimpanzees and gorillas have yet not been able to demonstrate such intelligent behaviour.