Modern day humans, Homo sapiens, are an upright-walking species that lives on the ground and very likely first evolved in Africa about 315,000 years ago.  Homo sapiens is the only existing living member of what zoologists refer to as the human tribe, Hominini.  There is abundant fossil evidence to indicate that humans were preceded for millions of years by other primate-like hominins, such as Ardipithecus, Australopithecus, and other species of Homo, and that our species also lived for a time contemporaneously with at least one other member of our genus, Homo neanderthalensis (the Neanderthals). In addition, human predecessors have always shared Earth with other apelike primates, from the modern-day gorilla to the long-extinct Dryopithecus (giant ape). That humans are related to apes, both living and extinct, is accepted by anthropologists and biologists everywhere.

The exact nature of our evolutionary relationships has been the subject of debate and investigation since the great British naturalist Charles Darwin published his monumental books On the Origin of Species (1859) and The Descent of Man (1871).  Darwin never claimed, as some of his Victorian contemporaries insisted, that “man was descended from the apes,” and modern scientists would view such a statement as a useless simplification—just as they would dismiss any popular notions that a certain extinct species is the “missing link” between humans and the apes. There is theoretically, however, a common ancestor that existed millions of years ago. This ancestral species does not constitute a “missing link” along a lineage, but rather, a divergence into separate lineages.  This ancient primate has not been identified and may never be known with certainty, because fossil relationships are unclear even within the human lineage, which is more recent. In fact, the human “family tree” may be better described as a “family bush,” within which it is impossible to connect a full chronological series of species, leading to Homo sapiens.

 Primates diverged from other mammals about 85  million years ago (Mya), in the Late Cretaceous period, with their earliest fossils appearing over 55 Mya, during the Paleocene.  Primates produced successive clans leading to the ape superfamily, which gave rise to the hominid and the gibbon families; these diverged some 15–20  Mya. African and Asian hominids (including orangutans) diverged about 14 Mya. Hominins (including the Australopithecine and Panina subtribes) parted from the Gorillini tribe between 8 and 9 Mya;

Australopithecine (including the extinct biped ancestors of humans) separated from the Pan genus (containing chimpanzees and bonobos) 4–7 mya.  The Homo genus is evidenced by the appearance of Homo habilis over 2 Mya.  Anatomically erect modern humans emerged in Africa approximately 300,000 years ago.

Over their evolutionary history, humans gradually developed traits such as bipedalism, dexterity, and complex language, as well as interbreeding with other hominins, indicating that human evolution was not linear but weblike.  The study of the origins of humans involves several scientific disciplines, including physical and evolutionary anthropology, paleontology, and genetics; the field is also known by the terms anthropogeny, anthropogenesis, and anthropogony.

One of the oldest known primate-like mammal species, Plesiadapis, came from North America; another, Archicebus (forest dweller), came from China. Other such early primates include Altiatlasius and Algeripithecus, which were found in Northern Africa. Other similar basal primates were widespread in Eurasia and Africa during the tropical conditions of the Paleocene and Eocene.