The chief anatomical characteristics shared by chimpanzees, orangutans and gorillas (which set them apart from lesser primates), are the absence of a tail, a more or less upright posture and the high degree of development of the brain. However, these primates vary widely in way of life: orangutans live almost entirely in the trees, gorillas live primarily on the ground, but the chimpanzee--alone among the anthropoid apes--is equally at home in the trees and on the ground.

Habitat: Chimpanzees are found in the forests of Central and West Africa. They thrive in steamy, lowland rainforests, in mountainous forests and, in the western part of their range, the savannah.

Development: Chimps weigh about five pounds at birth (the gestation period is about seven-and-a-half months). Like a human baby, a chimp is almost completely helpless at birth and for the first 12 months, but at a few days old it is able to cling to its mother. By the age of eight or nine, a chimp may weigh 88 pounds and is sexually mature. Growth continues until the animal is about 13 years old. An average adult chimp stands about four feet tall, females weight about 99 pounds, the male, 121 pounds; larger individuals can weigh nearly twice as much. Chimps often live 40 years or longer.

Dependent infancy and the long childhood of chimps are indications of their close relationship to man. Other characteristics are the chimp's hands, which have an opposable thumb so they can pick up objects between thumb and forefingers and, most importantly, a brain large in relation to body size and weight.

A baby chimpanzee learns by watching its mother. For two to three years it shares a nest with its mother, usually built in the treetops and fashioned from branches; sometimes it is crafted of grass blades on the ground. The baby travels with its mother six to eight hours daily to feed on fruit, leaves, bark and, on occasion, meat. In the trees, chimpanzees swing can swing easily from branch to branch; on level ground or on thick aerial branches they move about on all fours.

By the age of two, a young chimp will begin to find part of its food itself. Researchers have observed young chimps begging food from their mothers or other females. Chimps live in groups of up to 40 individuals. Within this group, a mother and her young comprise the most stable social unit. Males are not tied to infant care and, if they are not needed for defense, may range far afield in search of food, sometimes killing small game.

Learn More from World Wildlife Fund:
Social Behavior, Predators, Conservation