What is a Monkey?

With their long tails, grasping hands and cheeky expressions, monkeys have entertained us for centuries. But those fast reactions and clever thinking didn’t evolve just for our amusement — they are adaptations for life in complex societies high in the treetops. The term “monkey” actually refers to most members of a group of mammals called simiiformes, ranging from tiny pygmy marmosets to giant lowland gorillas. The subset of large simiiformes that lack tails are known as apes, not monkeys, and they are found mainly in Africa and Southeast Asia.

Most monkeys live in groups, called troops. They use a variety of social systems to form strong bonds, care for offspring and work together to solve problems. For example, titi monkeys have a pair-bonded system where males and females live together in the same troop. Other species, such as macaques and capuchins, have more multimale, multifemale groups.

Monkeys communicate with each other using a variety of vocalizations, facial expressions and body movements. For example, some monkeys will yawn to show they are angry or threaten another monkey. Others have pouches in their cheeks that they use to store food. Cotton-topped tamarins even raise and lower the crest of hair on their heads to emphasize their faces.

Unfortunately, many types of monkeys are endangered. They are hunted for meat and sold as pets, which can be dangerous to them. And they are increasingly finding their way into places where they don’t belong — disturbing the balance of ecosystems and creating conflicts with humans.