Chimpanzees showed altruistic behavior in a test conducted by Emory University researchers at the Yerkes National Primate Research Center. The results are published in the August 8, 2011, online edition of Proceedings of the National Academy of Sciences. This research comes on the heels of the 54-million-dollar opening weekend of the movie, “Rise of the Planet of the Apes.”
In the study, Yerkes researcher Victoria Horner and colleagues offered seven adult female chimpanzees a choice between two similar actions. One choice rewarded both the the lead study chimpanzee participant and a partner. Another choice rewarded only the chooser. In each trial, the chooser, which was always tested with her partner in sight, selected between differently colored tokens from a bin. One colored token could be exchanged with the human experimenter for treats for both members of the pair, indicating what’s called prosocial behavior — unselfish behavior that benefits the group. The other colored token would result in a treat only for the chooser, which is regarded as a selfish move.
All seven chimpanzees showed an overwhelming preference for the prosocial choice. What’s more, the study showed the choosers behaved altruistically especially towards partners who either patiently waited or gently reminded them that they were there by drawing attention to themselves. The chimpanzees making the choices were less likely to reward partners who made a fuss, begged persistently or spat water at them, which the scientists say shows the chimpanzees’ altruism was spontaneous and not subject to intimidation.
Examples of this simplified experimental design include allowing the study partners to sit close together and ensuring conspicuous food consumption, which the researchers achieved by wrapping pieces of banana in paper that made a loud noise upon removal.
Doctor Horner explained the results:
We were excited to find female after female chose the option that gave both her and her partner food. It was also interesting to me that being overly persistent did not go down well with the choosers. It was far more productive for partners to be calm and remind the choosers they were there from time to time.
The authors say this study answers questions about whether chimpanzees show altruism. In the wild, researchers have reported apes helping each other and showing empathy for those in distress. In this small but well-controlled experiment, the researchers confirmed that chimpanzees perform acts of altruism. And since humans share a common ancestor with chimpanzees, this research sheds light on the origins of human altruism.
Emory University produced the video below to contrast the portrayal of apes in “Rise of the Planet of the Apes” with a realistic one.
Bottom line: Chimpanzees showed altruistic behavior in a test of seven females in captivity at the Yerkes National Primate Research Center at Emory University. This research sheds light on the origins of human altruism, since humans share a common ancestor with chimpanzees. Results of the study appear in the August 8, 2011, online issue of Proceedings of the National Academy of Sciences.