Any member of an adaptively diverse group of extinct hominin species that inhabited Africa between approximately 4.2 million years ago (MYA) and 1.2 MYA. The term australopith is used in preference to the term australopithecine, which is sometimes still erroneously employed in the paleoanthropological literature, because australopithecine implies that its members form a meaningful taxonomic group (that is, the Australopithecinae) and it is clear that they do not. Rather, the australopiths are a paraphyletic group of species that are linked by relatively few morphological features, but which are believed to share a general “adaptive grade.” In addition to being bipedal (a characteristic shared by all hominins), they possess an ape-sized brain (approximately 350–550 cm³; 21–34 in.³); small, nonhoning canines, relatively large premolars and molars with thick enamel; and thickly buttressed mandibles. There are nine species considered as australopiths and although some workers regard them all as belonging to a single genus, Australopithecus, it is evident from numerous studies that at least two and possibly three genera are represented. All nine australopith species are known only from Africa; the fossils come from a wide geographical area, encompassing parts of South Africa, Malawi, Tanzania, Kenya, and Ethiopia. The species are listed in the table, together with their currently known geographical and geochronological distributions. Their geochronological distribution is compared with other hominin species in Fig. 1. See also: Anthropology; Apes; Fossil apes; Fossil humans; Fossil primates; Molecular anthropology; Physical anthropology

The earliest representatives of people anatomically similar to living humans that evolved from more archaic humans approximately 150,000–300,000 years ago. The general process by which early modern humans (Homo sapiens) emerged from late archaic humans and eventually replaced them is gradually emerging. They evolved locally from preceding archaic humans in eastern Africa. Over the succeeding 50,000 years, their range expanded and contracted modestly with changing global climatic cycles to include, at times, the Mediterranean, southwest Asia and portions of northeastern Africa. Early modern humans and their biology and way of life, therefore, initially had little advantage over late archaic humans. See also: Anthropology; Fossil humans

Ancient fossilized members of human beings and those species directly ancestral to modern humans. Fossil humans comprise all prehistoric skeletal remains of humans that are archeologically earlier than the Neolithic (necessarily an imprecise limit, but approximately 10,000 years ago), regardless of the degree of mineralization or fossilization of bone, and regardless of whether the remains may be classed as Homo sapiens (anatomically modern humans) or a more ancient species. In this sense, the term "humans" is used broadly to mean all primates related to living people since the last common ancestor of people and African apes; therefore, this definition encompasses all species included in the genera Homo, Australopithecus, Ardipithecus, and Paranthropus (as well as potentially others). In the last decade, several important discoveries have contributed to our understanding of human evolution, including the discovery of Homo naledi (Fig. 1) in South Africa, the genetic analysis of the Denisovans in Siberia, the remains of small-bodied Homo floresiensis in Indonesia, a nearly complete skull of Homo erectus in Georgia, and evidence of Acheulean stone tool-making technology in Algeria dating back to 2.4 million years ago. See also: Anthropology; Apes; Australopith; Fossil; Fossil apes; Fossil primates; Neolithic; Phylogeny; Physical anthropology; Primates

A species of fossil human from the Pleistocene representing a specialized side branch in human evolution in Africa and Eurasia. Homo erectus (Fig. 1) was a common, widespread, and long-surviving ancestor of modern humans (H. sapiens). Fossil remains of the extinct H. erectus species have been found in Africa and Eurasia, dating from about 1.9 million to 100,000 years ago. The first fossils were found in Java in 1893 and were termed Pithecanthropus erectus. Most of the finds in China and across Africa were given distinctive generic and specific names, but all are now usually considered local variants or subspecies of the single species known as H. erectus. See also: Anthropology; Extinction; Fossil; Fossil humans; Pleistocene

A group of late archaic humans (Homo neanderthalensis) from Europe, southwest Asia, and central Asia that immediately preceded the first modern humans in those regions. The closest evolutionary relatives of modern humans are the Neandertals (also spelled Neanderthals). Most researchers place these archaic humans in their own species, Homo neanderthalensis (Fig. 1), emphasizing the differences between them and modern humans. Still, some investigators place them within the species Homo sapiens, recognizing their close affinities to modern humans. The Neandertals have been estimated by radiocarbon dating (a method of obtaining age estimates on organic materials) to have lived from approximately 300,000 to 35,000–30,000 years ago. See also: Anthropology; Early modern humans; Neandertal DNA; Neandertal genome; Neanderthal extinction

The subfield of anthropology that deals with human and nonhuman primate evolution, the biological bases of human behavior, and human biological variability and its significance. Physical anthropology is a branch of anthropology that investigates the evolution and diversity of humans, as well as their extinct ancestors and related nonhuman primates (Fig. 1). Physical anthropology is often referred to as biological anthropology to signal the close links with other biological sciences. The term physical anthropology is largely an American and British invention; in most European and many other countries, physical anthropologists are the only anthropologists, whereas persons who study behavioral aspects of the human condition are known as archeologists, ethnologists, linguists, or prehistorians. In addition, the term human biology is often used instead of physical anthropology, especially in relation to curricula in the health sciences. See also: Anthropology; Archeology; Biology; Evolution; Human biological variation; Primate