Monkeys also possess a certain sense of humor, similar to that shown by children as early as 8 months. All four great apes, orangutans, chimpanzees, bonobos and gorillas, engage in playful teasing behaviors.
This type of behavior must have already evolved in the last common ancestor of humans and monkeys, at least 13 million from years ago. Joking is an important part of human interactions and has much in common with playful teasing, which is considered, from a cognitive point of view, a precursor to joking.