Australopithecus

Australopithecus is a genus of extinct hominins that lived in Africa from about 4.2 to 1.4 million years ago, with fossils found in East and South Africa. Members of the genus are among the earliest known walkers on two legs, but they also retained adaptations for climbing. They had small brains compared with later Homo species, averaging roughly 400 to 550 cubic centimeters.

Their faces were generally prognathic, with large molars and premolars suited to processing a variety of plant foods. Body size and limb proportions vary among species, but many Australopithecus individuals were stocky and bipedal, with relatively long arms indicating some tree-climbing ability. The combination of bipedal locomotion and primitive features places the genus as an early and diverse branch of the human family tree.

The genus includes several well-known species. Australopithecus afarensis, from eastern Africa (about 3.9–2.9 million years old), is represented by the partial skeleton known as Lucy. Australopithecus africanus, from South Africa (about 3.0–2.0 million years old), and Australopithecus anamensis (about 4.2–3.9 million years old) are also recognized. Australopithecus sediba, from South Africa (about 1.98–1.78 million years old), shows a mosaic of primitive and more derived traits. Some robust forms once placed in Australopithecus are now often classified in Paranthropus.

The relationship of Australopithecus to the Homo lineage is debated. It is generally viewed as an early, diverse group that predates Homo, providing important insights into the evolution of bipedality, dentition, and the emergence of our genus.