Monkeys are a fascinating part of the natural world, living in forests and rainforests from Africa to Asia and as far north as Japan. They are also a vital part of our own ecosystems, pollinating plants and spreading their seeds to other areas.
Some monkey species have adapted to harsh environments, such as desert-like savannas and snowy mountains. For example, Japanese macaques (Macaca fuscata), commonly known as snow monkeys, grow heavy insulating coats in winter to maintain body heat in the cold forest temperatures. They can also swim, using their webbed toes to paddle through streams and rivers.
Most monkeys live together in a group called a troop. A troop can be as small as a few individuals or as large as thousands. Several different kinds of social systems exist within monkey troops, including one-male groups, in which a dominant male has access to females for mating and leads a group of his mates and offspring. Unattached adult males sometimes form separate all-male groups. Monkeys communicate with each other through grooming, which not only keeps their fur clean of dirt and dead skin but also builds relationships and makes peace between rivals.
Like humans, monkeys are able to express emotions through their faces, and their facial expressions can convey a wide range of feelings from happiness and compassion to anger and fear. Some species of monkeys also howl to mark territory or to alert other members of the troop to danger. In addition to vocalization, monkeys use their hands and feet to move through the trees, clinging and leaping from branch to branch. They can also use their prehensile tails to hold onto branches or for balance and movement, as well as walk on all four limbs (quadrupedal).