Chimpanzees are omnivores, meaning they eat both plants and animals. Young chimpanzees learn from observing their mothers and other adults which foods are safe to eat and where ripe food is located. For the first few months of its life, a baby chimp clings to its mother's belly as she travels with it everywhere. After that, young chimpanzees will spend the next seven to ten years at their mothers' sides learning how to groom, make nests in trees, find food, and use tools. Although they normally walk on all fours (knuckle-walking), chimpanzees can stand and walk upright. By swinging from branch to branch they can also move quite efficiently in the trees, where they do most of their eating and sleeping.