Monkeys are highly social and interact through silly play, cuddling, intertwining tails and holding hands. They are intelligent and playful, and they enjoy having fun with each other through games. Adults may sit close to one another and touch each other’s faces as a means of strengthening social bonds.

Monkeys also use facial expressions to express love, fear or sadness. Excessive grooming, which can often appear to be silly behavior to humans, is an integral part of social interaction through touch. Monkeys spend long hours in careful and attentive combing through fur of others with their fingers, removing debris and bugs. It is a way to show affection, peace and subordination.

Play and silly behavior in young monkeys also helps develop motor skills. Researchers have found that male Rhesus macaque monkeys are more intent on play fighting than females. As adults, males must be prepared to aggressively defend the troop, skills that are developed through climbing, wrestling and chasing behaviors when they are young. Male juveniles also engage in play for longer periods of time than females.

Head shaking in chimps, orangutans and gorillas may appear frivolous and silly, but it is a social move learned in infancy. Infant monkeys lift their heads during breastfeeding. Those that do not want to feed shake their heads. The behavior carries into adulthood, when head bobbing, yawning, grinning or pulling lips can also be a sign of aggression.