The first apelike beings appeared in the Oligocene period, which began about 38 million years ago. The first apes thought to be on the line to humans appeared in the Miocene, which extends from 5 to 25 million years ago. These include the dryopithecine ape Proconsul africanus
and Ramapithecus, which is now thought to be an ancestor of the orangutan.
Then came the Pliocene period. During the Pliocene, the first hominids, or erect-walking humanlike primates, are said to appear in the fossil record. The term hominid should be distinguished from hominoid, which designates the taxonomic superfamily including apes and humans. The earliest known hominid is Australopithecus
, the “southern ape,” and is dated back as far as 4 million years, in the Pliocene.
This near human, say scientists, stood between 4 and 5 feet tall and had a cranial capacity of between 300 and 600 cubic centimeters (cc). From the neck down, Australopithecus
is said to have been very similar to modern humans, whereas the head displayed some apelike and some human features.
One branch of Australopithecus,
known as the “gracile” or lighter branch, is thought to have given rise to Homo habilis around 2 million years ago, at the beginning of the Pleistocene period. Homo habilis appears similar to Australopithecus except that his cranial capacity is said to have been larger, between 600 and 750 cc.Homo habilis is thought to have given rise to Homo erectus (the species that includes Java man and Peking man) around 1.5 million years ago. Homo erectus is said to have stood between 5 and 6 feet tall and had a cranial capacity varying between 700 and 1,300 cc. most paleoanthropologists now believe that from the neck down, Homo erectus was, like Australopithecus and Homo habilis, almost the same as modern humans. The forehead, however, still sloped back from behind massive brow ridges, the jaws and teeth were large, and the lower jaw lacked a chin. It is believed that Homo erectus lived in Africa, Asia, and Europe until about 200,000 years ago.
Paleoanthropologists believe that anatomically modern humans (Homo sapiens
) emerged gradually from Homo erectus. Somewhere around 300,000 or 400,000 years ago the first early Homo sapiens or archaic Homo sapiens are said to have appeared. They are described as having a cranial capacity almost as large as that of modern humans, yet still manifesting to a lesser degree some of the characteristics of Homo erectus, such as the thick skull, receding forehead, and large brow ridges. Examples of this category are the finds from Swanscombe in England, Steinheim in Germany, and Fontechevade and Arago in France. Because these skulls also possess, to some degree, Neanderthal characteristics (Gowlett 1984, p. 85; Bräuer 1984, p. 328; stringer et al. 1984, p. 90), they are also classified as pre-Neanderthal types. Most authorities now postulate that both anatomically modern humans and the classic Western European Neanderthals evolved from the pre-Neanderthal or early Homo sapiens types of hominids (Spencer 1984, pp. 1– 49).
In the early part of the twentieth century, some scientists advocated the view that the Neanderthals of the last glacial period, known as the classic Western European Neanderthals, were the direct ancestors of modern human beings. They had brains larger than those of Homo sapiens sapiens.
Their faces and jaws were much larger, and their foreheads were lower, sloping back from behind large brow ridges. Neanderthal remains are found in Pleistocene deposits ranging from 30,000 to 150,000 years old. However, the discovery of early Homo sapiens in deposits far older than 150,000 years effectively removed the classic Western European Neanderthals from the direct line of descent leading from Homo erectus to modern humans.