Australopithecus garhi

A. garhi lived about 2.5 million years ago. Although similar to other australopithecines, it displayed some surprising features. The fossils are significant as they help fill the period between 2 and 3 million years ago; a time with a poor human fossil record.

Background of discovery

Age

The fossils are dated to 2.5 million years ago. However, this is a date for the fossils only, not a date range for the species. More fossils need to be found in order for a species time range to be determined.

Important fossil discoveries

Field work in Bouri from 1996-1998 recovered a number of fossils from multiple closely-situated sites.

The type specimen (BOU-VP-12/130) is a partial cranium discovered in 1997 by Yohannes Haile-Selassie in Bouri, Ethiopia. A second cranium, lower jaws and a partial skeleton have been found at nearby sites. These may represent the same species, however the discoverers point out that the skeletal remains need not belong to the same species as the skulls. This species was announced in 1999.

What the name means

The genus or group name Australopithecus is derived from the Latin word ‘australo’ meaning ‘southern’ and the Greek word ‘pithecus’ meaning ‘ape’. The species name, garhi, means ‘surprise’ in the Afar language. This name was chosen because the scientists who discovered the skull were surprised by some of the features of the skull, in particular the enormous back teeth.

Distribution

All fossil have been found at sites in the Middle Wash, Bouri, Ethiopia.

Relationships with other species

More fossils are needed before it is possible to determine where this species fits on our family tree. Its similarity to A.afarensis suggests it evolved from this species. It may be a direct ancestor of modern humans, representing an evolutionary link between the Australopithecus and Homo, or it may belong on a side-branch.

Key physical features

Brain

• size about 450 cc, similar to other australopithecines

Body size and shape

• probably slightly larger than A.afarensis

Jaws and teeth

• very large canines, molars and premolars
• thick tooth enamel
• rectangular or U-shaped dental arcade
• diastema (gap between canines and incisors) often present in the upper jaw. This is a primitive feature.
• similar in appearance to A.afarenis but has more advanced features in the teeth

Skull

• prognathous or projecting lower face
• like many australopithecines, including some A.afarensis, it has a sagittal crest for anchoring large jaw muscles

Limbs

• limb bones (although it is debated whether they belong to this species) are intermediate in proportion between A.afarensis and H.ergaster. Arm length was relatively long, but leg length was more humanlike compared to A.afarensis.

Lifestyle

Environment and diet

A changing climate had thinned the forests that once dominated this region, and savannah grasslands were becoming widespread.

It most likely ate plant material and possibly some meat. If the antelope bones found at the site were butchered by this species, then they must have included significant amounts of meat and marrow in their diet.

Culture

The skeletal remains were found associated with antelope bones bearing cut marks, apparently from stone tools. Stone tools were not found at this site, but at the nearby, contemporaneous site Gona. These are the earliest dated stone tools that have been found, but may have been left by another species.

Further reading:

Asfaw, B; White, T; Lovejoy, O; Latimer, B; Simpson, S; Suwa, G (1999). ‘Australopithecus garhi: a new species of early hominid from Ethiopia’. Science. 284 (5414): 629–35

De Heinzelin, J; Clark, JD; White, T; Hart, W; Renne, P; Woldegabriel, G; Beyene, Y; Vrba, E (1999). ‘Environment and behavior of 2.5-million-year-old Bouri hominids’. Science. 284 (5414): 625–9