Monkey mothers bite their babies as a form of discipline. It may sound crude, but it is an essential part of raising infant monkeys.
Monkeys in the wild often live in large social groups and the mother must show her dominance to ensure the safe rearing of her young. This means that the female must be able to protect her infants from stress, danger, and potential threats. Biting is a natural way for monkey mothers to demonstrate their power over their babies and teach them certain behaviors.
As a result, the baby monkeys quickly learn how to behave and respond to threats.