Chimpanzee Cooperation (1 of 2) (image) Emory Health Sciences Caption The study apparatus required that chimpanzees remove a barrier in order for another chimpanzee to simultaneously pull in a tray baited with food. The apparatus was mounted to the outdoor enclosure, allowing the chimpanzees to come and go as they wanted. Credit Yerkes National Primate Research Center Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.