Jocko, a chimpanzee, was once given a large bunch of bananas by a zookeeper after the more dominant members of the chimpanzee's troop had wandered off.
Evidence
Jocko, a chimpanzee, was once given a large bunch of bananas by a zookeeper after the more dominant members of the chimpanzee’s troop had wandered off.
In his excitement, Jocko uttered some loud “food barks.”
The other chimpanzees returned and took the bananas away.
The next day, Jocko was again found alone and was given a single banana.
This time, however, he kept silent.
Conclusion
The zookeeper concluded that Jocko’s silence was a stratagem to keep the other chimpanzees from his food.
Evaluate
It’s possible that Jocko had learned from his mistake and had decided to keep quiet the second time as a way to keep his banana. It’s also possible that a single banana did not excite Jocko as much as a large bunch of bananas. And because Jocko didn’t get so excited, he didn’t accidentally alert the other chimpanzees of the banana’s arrival.