At birth, the baby chimpanzee weighs less than 5 pounds and depends entirely on his mother to survive. Unable to move alone, he clings to his mother, who wears it under her belly so as not to lose it. At the age of one year, he can climb on her back, so that it carries on her shoulders safely. Until he's 2 years old, the child is sometimes on the back of his mother, sometimes alone, to discover his environment. He enjoys swinging, jumping on branches or fighting. The baby chimpanzee learns through the game to discover its peers, and to join the group to find its place.