Test Setup (IMAGE) Max Planck Institute of Geoanthropology Caption The test apparatus involved a barrier separating the participants from a food reward, with two openings on opposite ends that were controlled by a researcher. When the first animal approached an opening, the door before it would shut while the opposite door remained open, allowing the partner to enter first and access the food. The door then remained open, so that other animal could then enter. Thus the animals had to cooperate in two ways - first by positioning themselves on opposite ends of the barrier and then by timing and coordinating their approaches towards the barrier. Credit Image: Sylvio Tüpke Usage Restrictions This image may only be used in the context of reporting on this publication and with appropriate credit information. License Licensed content 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.