A monkey is a primate of the Haplorrhini suborder and simian infraorder—a group that also includes great apes such as gorillas, chimpanzees, and orangutans. Scientists further divide monkeys into Old World and New World varieties. Many species are arboreal, but some live on the ground as well. Monkeys are known for their intelligence and inquisitiveness. They are good at solving problems, but they do not reach the cognitive levels of the great apes. Some monkeys, such as capuchins, spontaneously use objects as tools. They also tend to learn from other monkeys’ experience, but individual monkeys more or less have to figure things out for themselves.
Monkeys use vocalizations and facial expressions to communicate in their large groups. Staring at other monkeys can mean, “back off–this is my territory.” A loud vocalization can signal a warning to other monkeys or the end of a conflict. Some monkeys have tails, which they wag to communicate their mood and other information to other members of the troop. A swaying tail can mean, “I’m happy.” A straightened tail can indicate that a monkey is angry.
Many monkey species are endangered, especially those living in human habitats. People cut down the trees that monkeys need to live in the forest, and they hunt or capture monkeys for food and pets. The illegal wildlife trade puts another strain on monkey populations, as does habitat loss. Fortunately, biologists and conservation groups breed some monkeys in captivity and reintroduce them into the wild. For example, the golden lion tamarin is recovering from being nearly extinct.