Adult monkeys play. They wrestle each other for no reason. They drop fruit on each other from a great height. They run at each other and stop, and then run away, and then come back.
No one told the adult monkey that play is for children. The adult monkey would have laughed at this and then bitten the messenger gently on the ear.
We quit playing somewhere around twelve and called it maturity. The macaque is forty in human years and is currently dunking another macaque into a hot spring. He looks great. He is fine.