Chimpanzees Show Impulsive Behaviors In Cooperating For Food
June 13, 2014

Chimpanzees Show Impulsive Behaviors In Cooperating For Food

Gerard LeBlond for - Your Universe Online

Researchers from the Yerkes National Primate Research Center at Emory University discovered in a new study that chimpanzees within a socially contained setting, impulsively cooperate with each other, selecting a partner of their choosing. The study findings are published in the June 12 issue of PeerJ.

The chimpanzees observed had no pre-training and were not restricted on which partners they could choose. The findings reveal these primates spontaneously cooperated successfully 3,565 times over the course of 94 one-hour sessions. As the sessions progressed, the success rate increased; but when there was an absence of a partner, the success rate decreased, indicating the chimpanzee needed a partner for success.

“Cooperation among primates has attracted considerable research because of the evolutionary implications that such research has for human behavior and the ubiquity of cooperation among wild primates,” said lead author Malini Suchak, PhD.

By letting the chimpanzees pick their own partner they could decide which one would be more beneficial and cooperative.

“Cooperation is often regarded as less puzzling than altruistic behavior, but only in an evolutionary sense. In the moment, cooperation often consists of a series of potentially complex decisions involving a choice of partners. When multiple partners are available, an individual must consider with whom to cooperate, if that individual has been a good partner previously, how much to invest in the partner, what to expect in return and if the cooperation will yield more benefits than solitary effort,” Suchak continued.

Suchak's study consisted of all 11 members of a chimpanzee group in a large outdoor enclosure at the Yerkes National Primate Research Center Field Station. This study was in a more complex environment than normal studies. The chimpanzees were allowed to choose within the group which mate to cooperate with. The study involved dyadic (using one chimpanzee) and triadic (using two chimpanzees) cooperation. It also explored the cooperative nature of the female’s dynamics. The information gathered will help determine the evolution of cooperative tendencies.

An apparatus mounted on the outdoor enclosure required one chimpanzee to remove a barrier so its partner could retrieve a tray of food simultaneously. The chimpanzees were also allowed to come and go as they pleased during the hour long test sessions.

“That the chimpanzees preferentially approached the apparatus when kin or non-kin of similar rank were present shows a preference for socially tolerant partners, and this demonstrates that in the midst of a complex social environment, chimpanzees spontaneously initiate and maintain a high level of cooperative behavior,” Suchak said.

“Because previous research could only elicit cooperation in a much more controlled setting, we thought more complex, cooperative behavior might have uniquely evolved in humans. This study demonstrates chimpanzees are more cooperative than we realized, and we've yet to fully explore the extent of the similarities between chimpanzee and human behavior in this regard,” Suchak concluded.

Other members of the research team included Yerkes researchers Frans de Waal, PhD, Matt Campbell, PhD, and Tim Eppley.