How do you know when animals are working together? Just because two animals got something done jointly doesn’t mean they cooperated. They might have succeeded by dumb luck, or trial and error. Scientists who study animal minds, though, would really like to know when cooperation happens on purpose—and how animal partners manage to communicate with each other.
Studies in capuchin monkeys and chimpanzees hinted that the primates coordinated their actions by glancing at each other. (But this