Members of the family Hominidae, including our own species Homo sapiens, our presumed forebears Homo erectus and Homo habilis, and forms believed to be closely related called collectively the australopithecines. Many scientists now also include the African great apes—the two chimpanzees and gorilla—in the human family, rather than grouping them with the more distantly related Asian apes. The traditional way of grouping the large apes (chimpanzees, gorilla, and orang-utan) is in their own family, Pongidae. Estimates of the date of divergence of the ape and human lineages vary. The Asian apes probably branched off 8–12 million years ago and the African apes 10–5 million years ago. The stages of development in which humans diverged from ape-like ancestors and took on their present form took at least five million years. Many details remain uncertain, particularly of the relationship between the australopithecines and the Homo lineage, and the position of such remains as those found at Broken Hill, in central Zambia. Here, skeletal material, once called Rhodesian Man, is now usually referred to as Kabwe or Broken Hill Man. These finds are believed to represent a population in Africa 400,000–200,000 years ago that is transitional between late Homo erectus and early or ‘archaic’ Homo sapiens.

The first australopithecine fossil was discovered at Taung in southern Africa in 1924 and named Australopithecus africanus (southern ape of Africa). Since then, australopithecine fossils have been found in southern and eastern Africa but the relationships between the different forms are still far from clear.

Current opinion divides them into two, or perhaps three main groups that date from over 4 million to nearly 1 million years ago. One of the oldest (4–3 million years ago) and most ape-like is Australopithecus afarensis, now known from eastern African sites. This species is often linked closely to Australopithecus africanus (3–2 million years ago), best represented at Sterkfontein and Makapansgat in southern Africa. Some authorities consider both these species are human ancestors; others rule out A. africanus, some even discount both from being human ancestors. Australopithecines were clearly capable of walking upright but their brains were still ape-like. It is uncertain if they made tools.

Homo habilis (‘handy man’) refers to a group of human fossil remains found at Olduvai Gorge in Tanzania in the early 1960s; they are now known from other eastern African sites, and perhaps also from southern Africa. They date from about 2.5 million to 1.6 million years ago. Although similar in size to the contemporary australopithecines, their brains were larger, their faces more human-like, and they may have evolved into Homo erectus. They were probably the first makers of stone tools, such as the simple pebble and flake artefacts collectively called the Oldowan industry.

Homo erectus (‘upright man’), who may have been the predecessor of our own species, Homo sapiens, lived in Africa and Asia and possibly in Europe. This hominid was larger than the australopithecines and Homo habilis, with a brain approaching the size of a modern human brain. However, the facial bones remained relatively massive and the skull was long and low. One of the hallmarks of this species was a teardrop-shaped stone tool flaked on both sides, the Acheulian handaxe, which was more specialized than the Oldowan tools of Homo habilis. Homo erectus was the first member of the human lineage to control and use fire, which with its use of clothing, may have contributed to its spreading from its place of origin in tropical East Africa. It may have evolved from Homo habilis, by 1.6 million years ago. By around 1 million years ago or not long before these hominids are presumed to have begun the travels that took them as far as China (Peking Man) and Indonesia (Java Man). The last representatives disappeared 400,000–200,000 years ago.

Homo sapiens (‘wise man’), our own species, appeared about 400,000–200,000 years ago. By this stage the brain had enlarged to the modern size, the skull bones had become less heavy, and the back of the head was rounded. The next development is obscure as the Homo sapiens lineage apparently split into two main lines, one leading to the Neanderthals (Homo sapiens neanderthalensis), the other to fully modern people (Homo sapiens sapiens). The latter development took place gradually during the past 125,000 years. Anatomical and genetic evidence support the idea that this happened in Africa, but it is possible that there was at least one parallel development in the Far East. In the Middle East, anatomically modern humans had appeared by around 50,000 years ago; in Europe, they came slightly later, and more abruptly around 35,000 years ago. The earliest modern Europeans are often called Cro-Magnons. It is not known what part, if any, the Neanderthals played in these Middle Eastern and European developments. Very likely they were not our direct ancestors but they may have interbred with modern people entering Europe from Africa via the Middle East.

With the evolution of modern people came marked advances in tool technology, rapid increase in population, the grouping of social activities in dwellings, and the first appearance of art; the cultural period called the Upper Palaeolithic had begun. These Upper Palaeolithic people almost certainly had a spoken language. With population growth came the colonization of new territories, which seems to have begun soon after the origin of fully modern humans. People had reached New Guinea and Australia from Indonesia by at least 40,000 years ago; there they developed Australoid characteristics in isolation. The timing of the first settlement of the New World is more controversial. It was probably before 15,000 years ago but there is little firm archaeological evidence so far for an earlier colonization. Genetic, linguistic, and anatomical evidence of modern Amerindians, however, is increasingly suggesting that the first entry into North America occurred between 40,000 and 30,000 years ago.

Neanderthals lived in Europe, the Near East, and Central Asia from about 130,000 to 30,000 years ago. No traces of people with characteristic (‘classic’) Neanderthal features are known from Africa or the Far East. They are named after the Neander valley near Düsseldorf in Germany where part of a characteristic skeleton was discovered in 1856. Neanderthals flourished particularly during the last Ice Age and were adapted for living in cold environments. Called Homo sapiens neanderthalensis to distinguish them from fully modern people Homo sapiens sapiens, their features included heavy bones, strong musculature, large brow ridges across a sloping forehead, and larger brains than those of fully modern people. Neanderthals were probably the first people to have burial rites. Flint tools of Mousterian type are usually found with their remains and characterize the Middle Palaeolithic period.

The part played by Neanderthals in later human evolution is controversial. One widely held view is that none were our direct ancestors. A study of DNA undertaken in 1996 indicated that the Neanderthals were a separate species and neither evolved into modern humans nor interbred with other early humans before they became extinct. An alternative opinion is that some Neanderthal groups evolved into fully modern people or that at least some interbreeding between Neanderthals and modern humans took place.

If they were an evolutionary dead end, the reason for their extinction 50,000–30,000 years ago remains a mystery (the date varies according to geographical locality). It is possible that they became too specialized and were supplanted by modern people migrating into Europe from elsewhere, probably Africa via the Middle East.

Palaeolithic peoples included hunter gatherers who subsisted from the natural environment, without involvement in agriculture of animal husbandry. They survived by gathering wild fruit and vegetables, and by hunting. Theirs is the earliest and simplest form of human organization, and has been found all over the world: Australian Aborigines, the Arctic Inuit, and the Kung-San in southern Africa are all examples of modern hunter-gatherers. They have a nomadic way of life, following seasonal food supplies. They are organized in bands consisting of close kin, but these bands fluctuate in size as members move in and out, according to food availability. Marriage is a very loose institution, and lineage is not considered of great importance. Hunter-gatherer society is egalitarian: leadership is usually based on individual ability and is not hereditary. Relations between men and women are also more egalitarian than in many sedentary societies, though there is a basic division of labour, the men hunting game while the women do most of the gathering. Cro-Magnons are early modern people (Homo sapiens), found in Europe until about 10,000 years ago. They were generally more heavily built than humans today but otherwise had the same anatomical characteristics. They appeared around 35,000 years ago and are named after a rock shelter in the Dordogne, France, where four adult skeletons, an infant’s skeleton, and other remains were found in 1868. With the skeletons were Upper Palaeolithic flint tools of Aurignacian type and signs of decorative art in the form of pierced sea shells. The ancestry of Cro-Magnons is unclear. It was once believed these people were the direct descendants of Neanderthals, but it is now thought that they evolved elsewhere, probably in Africa, replacing the Neanderthals within a few thousand years of reaching Europe. The cave-dwellers first used caves as shelters. This became widespread during the Middle and Upper Palaeolithic periods, when humans penetrated for the first time into the northern tundra environments in front of the ice-sheets of the last glaciation. Since the remains of open-air campsites, such as wind-breaks or tents, are generally less well preserved and less likely to be discovered than bones and tools incorporated in cave sediments, early investigators imagined that Stone Age people lived entirely in caves. This has now been refuted by the excavation of huts and tent-foundations preserved under wind-blown sediments in the Ukraine, central Europe, and France.