Australopithecus africanus: Encyclopedia - Australopithecus africanus

Australopithecus africanus

Australopithecus africanus was an early hominid, an australopithecine, who lived between 3.3 and 2.4 million years ago in the Pliocene. In common with the older Australopithecus afarensis, A. africanus was slenderly built, or gracile, and was thought to have been a direct ancestor of modern humans. Fossil remains indicate that A. africanus was significantly more evolved than A. afarensis however, with a more human-like cranium permitting a larger brain compared to body size and more humanoid facial features.

Australopithecus africanus - Taung Child

Raymond Dart was at Taung near Kimberley, South Africa in 1924 when one of his colleagues spotted a few bone fragments and the cranium on the desk of a lime worker. The skull seemed like an odd ape creature sharing human traits such as eye orbits, teeth and most importantly the hole at the base of the skull over the spinal column (the foramen magnum), indicating a human-like posture. Dart assigned the specimen the name Australopithecus africanus ("southern ape of Africa"). This was the first time the word Australopithecus was assigned to any hominid. Dart claimed that the skull must have been an intermediate species between ape and man, but his claim about Taung Child was rejected by the scientific community at the time. Sir Arthur Keith suggested that the skull belonged to a young ape, most likely from an infant gorilla.

Australopithecus africanus - Mr. Ples

Dart's theory was supported by Robert Broom. In 1938 Broom classified an adult brain endocast found by G. W. Barlow as Plesianthropus transvaalensis. On 1947-08-17 Broom and John T. Robinson discovered a skull, Sts 5, while blasting at Sterkfontein, and Broom classified it also as Plesianthropus transvaalensis (dubbed Mrs Ples by the press, presently thought to have belonged to a male Mr. Ples). Both fossils were later classified as A. africanus.

Australopithecus africanus - Interpretations

Charles Darwin suggested that humans had originally evolved from Africa, but during the early 20th century most anthropologists and scientists supported the idea that Asia was the best candidate for human origins. However, the famous Leakey family have argued in favor of the African descent since most hominid discoveries such as the Laetoli footprints were uncovered in Eastern Africa. The species A. africanus with it's presumably slightly more Homo-like post cranial features in comparison to A. afarensis is one of several Australopithecine candidates to have evolved into the genus Homo (ie. Homo habilis and Homo rudolfensis by 2.4 million years ago).

Australopithecus africanus - Physiology

Like A. afarensis, A. africanus the South African counterpart was generally similar in many traits, a bipedal hominin with arms slightly larger than the legs (a physical trait also found in chimpanzees). Despite its slightly more human-like post cranial features, seen for example in the craniums Mr. Ples and Sts 71, other more primitive features including ape-like curved fingers for tree climbing are also present.

Due to other more primitive features visible on A. africanus, some researchers believe the hominin, instead of being a direct ancestor of more modern hominins, evolved into Paranthropus. The one particular robust australopithecine seen as a descendent of A. africanus is Paranthropus robustus. Both P. robustus and A. africanus craniums seem very alike despite the more heavily built features of P. robustus that are adaptations for heavy chewing like a gorilla. A. africanus, on the other hand, had a cranium which quite closely resembled that of a chimp, yet both their brains measure about 400 cc to 500 cc and probably had an ape-like intelligence. A. africanus had a pelvis that was built for slightly better bipedalism than that of A. afarensis. No stone tools of any sort have ever been found in association with australopithecines with the exception of 2.6 million year old Australopithecus garhi.

Adapted from the Wikipedia article "Australopithecus africanus", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki