According to scientific data, about10.2 billion years ago, in tropical and subtropical jungle areas, there lived a highly developed ancient ape "forest ape", which was the common ancestor of modern people and modern apes. The forest ape has a short and strong body, a wide and flat chest, and the forearm is as long as the leg. Forelimbs are not only crutches when walking, but also organs used to hang in the jungle to pick wild fruits. They live in groups like chimpanzees. Due to the massive disappearance of forests, a large number of forest apes have to walk underground. Walking in the field for a long time made them gradually evolve and learn to walk upright.