Modern humans (Homo sapiens sapiens) and their known predecessors Ardipithecus , Australopithecus , Homo habilis, Homo erectus, Homo sapiens neanderthal are hominids. The key characteristic of hominids is upright posture and a bipedal mode of locomotion. Other hominid anatomical distinctions that developed through time are a larger brain capacity, opposable thumb and precision grip, shorter arms and longer legs, wider birth canal, and shorter big toes. In addition to these biological differences, the humans ancestors evolved culture. The cultural changes the joined biological factors in human evolution changes involve the way of life, use of the environment, and interpersonal relations. Specific highlights of cultural developments through time were the development of stone tool use, control of fire, formation of social groups, cooperative work, burial rites, and portable and nonportable art by the end of the Pleistocene era.

The biological changes serve to mark the hominids as distinct from the other primates. Hominids exhibit size reduction in their faces, particularly the jaws and teeth as well as having thicker enamel on the teeth. The size reduction includes losing the bony ridges over the eyes and sagittal crest on top of the head. Conversely, the brain becomes larger in comparison to the body.

The closest living relatives of hominids are the apes. According to the biochemical evidence, the last common ancestor occurred at least five million years before present. The oldest known hominid is Ardipithecus ramidus from Ethiopia, dated to 4.4 million years ago. Next, Australopithecus existed in Africa from approximately 4-1 million years ago. The gracile australopithecines probably became extinct before two million years ago, either through evolution into the genus Homo or through replacement. Homo habilis is known from circa 2.3 million years ago in association with stone tools. Approximately 1.8 million years ago H. habilis was replaced by or evolved into H. erectus, which existed until 300,000 years ago. H. erectus was the first hominid to venture out of Africa and into Asia and Europe. Archaic Homo sapiens began appearing ca. 500,000 years before present. Homo sapiens neanderthalensis appeared in Europe, the Near East, and Africa about 200,000 years ago and persist until about 30,000 years ago. Modern humans (H. sapiens sapiens) first appear ca. 120,000 B.P. and are a result of the last 100,000-40,000 years. Controversy does exist for the classification of various hominid fossil finds and their ages of occurrence.