Please note: This is a companion version & not the original book. Sample Book Insights: #1 Humans are classified as a genus, or group, of animal species called Homo. We are also classified as sapiens, which means wise. We are the only existing human form. #2 The hominid family includes humans, bonobos, chimpanzees, gorillas, and orangutans. We have discovered many fossils of prehuman ancestors, such as Ardipithecus, Paranthropus, and Australopithecus, which are more closely related to us than they are to chimpanzees. #3 The hominin family tree actually looks more like a bush, which shows that hominins passed through a series of significant evolutionary stages, periods during which several related species possessed nearly the same body type and lifestyles. #4 The first stage in the evolution of human bipedalism was the transition from arboreal quadruped to imperfect bipedalism, meaning that these hominins were capable of walking on two legs but still remained arboreal.