Hominids are a subgroup of primates that includes human beings - the species Homo sapiens - and their immediate ancestors.
The earliest genus of hominids is called Australopithecus, meaning "southern ape." The oldest autralopithecine skeleton unearthed to date was found in eastern Africa in 1974. This fossil is between 3 million and 3.5 million years old. The shape of the pelvic bone indicates that the remains are those of a female. Scientists have nicknamed her Lucy. They classify Lucy and morphologically similar skeletons as Australopithecus afarensis. This species existed between 3 million and 4 million years ago. A. afarenis was shorter than modern humans, less than 1.5 m tall. A afareniss' cranial capacity was between 380 and 450 cm3, less than one-third of modern humans.
The next oldest species of autralopithecines, Autralopithecus africanus, lived 2.2 million to 4 million years ago. A. africanus was slightly taller and heavier than A. afarensis. Its cranial capacity was slightly larger, between 430 and 550 cm3.
Between 1.6 and 2 million years ago was Homo habilis (handy human) with a cranial capacity as great as 600 to 800 cm3. The next species is Homo erectus (upright human) found between .5 and 1.6 million years old. Their cranial capacity ranged between 700 and 1,250 cm3. Two skulls between 250,000 and 350,000 years old were found in Germany and Great Britain in the 1930's. These skulls are evidence of hominids transitional between H. erectus and H. sapiens.
They have both the large brow ridges of H. erectus and the very large cranial capacity of H. sapiens.
Hominid fossil skeletons from 35,000 to 130,000 years ago have been found in Europe, Asia, and Africa. They belong to a group called Neanderthals. Neanderthals were early H. sapiens. According to the fossil evidence, Neanderthals had heavy bones, thick brow ridges, and a small chin. However, skull sizes indicate that Neanderthals had a cranial capacity averaging 1,450 cm3. This is slightly larger than the cranial capacity of modern humans. Neanderthals were about 1.5 meters tall.
Hominid fossil skulls from about 35,000 years ago were first found in caves in southwestern France in 1868. Since then the fossil remains of these people, referred to as Cro-Magnons, have been found elsewhere in Europe as well as in Africa, Asia, and eve Australia. Cro-Magnons had a cranial capacity of about 1,400 cm3. They are distinguished from Neanderthals by their height forehead, prominent chin, and lack of brow ridges. Taller than Neanderthals, they stood about 1.8 meters tall. Cro-Magnons were H. sapiens and are regarded by scientists as modern humans. Paleonathropologists differ in their interpretations of how humans evolved. The different theories disagree how A. afarensis branched off, eventually evolving into humans.
The debate between paleoantopolists illustrates that this science is an ongoing process.
