Wikipedia:Today's featured article/July 26, 2018

The cooperative pulling paradigm is an experimental design in which animals cooperate to pull food towards themselves. Researchers use these experiments to try to understand how cooperation works and how and when it may have evolved. Meredith Crawford ran the first such experiment in 1937, attaching two ropes to a rolling platform that was too heavy to be pulled by a single chimpanzee. In another design, a rope comes loose if only one animal pulls it, and the platform can no longer be retrieved. Researchers look for signs of cooperation, such as when an animal waits for another animal's actions before pulling the rope. Chimpanzees, bonobos, orangutans, capuchins, tamarins, wolves, elephants, ravens, and keas appear to understand the requirements of the task, and other animals sometimes manage to retrieve the food. The superior scale and range of human cooperation comes mainly from the ability to use language to exchange social information.