Australopithecine
Extinct close relatives of modern humans, ancestral to Homo.
The australopithecines—formally grouped as Australopithecina or Hominina—include most species from the closely related genera *Australopithecus* and *Paranthropus*, and sometimes also *Kenyanthropus*, *Ardipithecus*, and *Praeanthropus*. They belong to the subtribe Australopithecina within the tribe Hominini. These extinct creatures are the close relatives of modern humans, and together with the living genus *Homo*, they form the human clade. The name comes from an older classification that placed them in a separate subfamily, the Australopithecinae. Within the group, *Australopithecus* species are often called "gracile australopithecines," while *Paranthropus* species are known as "robust australopithecines."
None of the groups usually assigned directly to this category survived, but the australopithecines are not truly extinct in the sense of having no living descendants. This is because the genera *Kenyanthropus*, *Paranthropus*, and *Homo* likely emerged as sister groups to a late *Australopithecus* species, such as *A. africanus* or *A. sediba*.
The australopithecines lived during the Late Miocene sub-epoch. They walked upright on two legs and had teeth similar to those of humans, but their brains were only slightly larger than those of modern non-human apes, showing less encephalization than the genus *Homo*. Humans (genus *Homo*) may have descended from australopithecine ancestors, and the genera *Ardipithecus*, *Orrorin*, *Sahelanthropus*, and *Graecopithecus* are possible ancestors of the australopithecines themselves.
Their post-cranial remains show they were adapted for bipedal locomotion, though they did not walk exactly like humans. They had a forearm-to-upper-arm ratio similar to the Golden Ratio—greater than in other hominins. They also showed more sexual dimorphism than members of *Homo* or *Pan*, but less than in *Gorilla* or *Pongo*. Average height is thought to have been between 1.2 and 1.5 meters, with weights ranging from 30 to 55 kilograms. Brain size likely fell between 350 and 600 cubic centimeters. The teeth behind the canines were relatively large and had more enamel than those of contemporary apes and humans, while the incisors and canines were relatively small. There was also little difference between male and female canines compared to modern apes.
Most scientists agree that the genus *Homo* appeared in Africa within the aust
- Time period
- Late Miocene sub-epoch
- Brain size
- 350 cc to 600 cc
- Height
- 1.2–1.5 metres (3.9–4.9 ft)
- Weight
- 30–55 kilograms (66–121 lb)
- Locomotion
- Bipedal
- Key genera
- Australopithecus, Paranthropus, Kenyanthropus, Ardipithecus, Praeanthropus
Lore & Background
The australopithecines occurred in the Late Miocene sub-epoch and were bipedal, dentally similar to humans, but with a brain size not much larger than that of modern non-human apes, with lesser encephalization than in the genus Homo. Their post-cranial remains show they were adapted to bipedal locomotion, but did not walk identically to humans. They had a forearm to upper arm ratio similar to the Golden Ratio – greater than other hominins. They exhibited greater sexual dimorphism than members of Homo or Pan but less so than Gorilla or Pongo. The postcanines were relatively large, with more enamel compared to contemporary apes and humans, while incisors and canines were relatively small, with little difference between males' and females' canines compared to modern apes.
Reader's Guide
The australopithecines are significant as the extinct, close relatives of modern humans and, together with the extant genus Homo, comprise the human clade. While none of the groups normally directly assigned to this group survived, the australopithecines do not appear to be extinct in the sense of having no living descendants, as the genera Kenyanthropus, Paranthropus, and Homo probably emerged as sisters of a late Australopithecus species such as A. africanus and/or A. sediba. Most scientists maintain that the genus Homo emerged in Africa within the australopithecines around two million years ago, though there is no consensus on within which species. Nearly every possible species has been suggested as a likely candidate, but none are overwhelmingly convincing. A minority view holds that australopithecines moved outside Africa, with some arguing robust australopithecines reached Indonesia and China, though such claims remain disputed. The genera Ardipithecus, Orrorin, Sahelanthropus, and Graecopithecus are possible ancestors of the australopithecines.
Did You Know?
- The term 'australopithecine' comes from a former classification as members of a distinct subfamily, the Australopithecinae.
- Australopithecines had a brain size of 350 cc to 600 cc, not much larger than that of modern non-human apes.
- Marc Verhaegen has argued that an australopithecine species could have been ancestral to the genus Pan (chimpanzees).
- A minority view among palaeoanthropologists is that australopithecines moved outside Africa, possibly reaching Indonesia and China.
More in Extinct Hominins 1-19
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