Humans’ earliest ancestors appeared in Africa about 27 million years ago. They ate fruit and walked on four legs. Several types of early apes, called proconsuls, evolved. Together with apes and monkeys, we belong to a group of mammals called primates. Since humans have DNA that is similar to chimpanzees, we likely have a common ancestor. This ancestral line split about six to ten million years ago. One important feature that primates developed was the opposable thumb. This enables primates to grasp and tightly hold objects. Another feature is binocular vision. Both eyes are aimed forward, making it easier to judge distances.