Australopithecus prometheus

Information About the Species

Australopithecus prometheus is a species of early hominin characterized by robust teeth and jaws, adaptations likely linked to a diet of tough, fibrous plant material such as roots, tubers, and hard fruits (Clarke & Kuman, 2019). The species shares bipedal locomotion with other australopithecines but is distinguished by its more specialized dietary traits. A. prometheus likely coexisted with A. africanus around 2 to 2.5 million years ago, contributing to our understanding of the evolutionary pressures that shaped early hominins (Clarke, 2019; Crompton et al., 2022). Fossils like the StW 573 skull from the Sterkfontein Caves provide key insights into the species' physical traits and its role in the broader context of hominin evolution (Clarke & Kuman, 2019).

Defining Features of the Species

Australopithecus Prometheus exhibits distinct characteristics that set it apart from other australopithecine species, particularly A. africanus. A key feature is its larger molars and premolars, which are an indication of adaptations for processing tougher, more fibrous foods. These teeth, combined with a robust jaw musculature, suggest that the species may have had a diet consisting of hard plant material such as roots, tubers, and tough fruits or seeds. The robust nature of the jaws and teeth reflects evolutionary adaptations to a dietary niche requiring stronger masticatory capabilities. A. Prometheus was bipedal and capable of upright walking, which aligns with the general behaviors of australopithecines. However, its larger and more robust teeth and jaw structure set it apart from other species like A. africanus, indicating a specialized adaptation to its diet (Crompton, 2022). While it was likely capable of limited arboreal behaviors, its reliance on bipedal locomotion suggests it spent significant time on the ground, using its teeth and jaws for processing tough plant materials (Clarke, 2019).

MLD 1 and StW 573 fossil skulls (Hawkes 2024)

Taylor, I. by K., & Welker, B. H. (2017)

Evolutionary Tree

Australopithecus prometheus likely lived around 2 to 2.5 million years ago, a time when multiple hominin species were emerging and diverging. It may have coexisted with other species like A. africanus, but with notable differences in its morphological and dietary adaptations. The species' robust teeth and jaw structure suggest that it may have branched off from the more gracile australopithecines into a more specialized lineage, capable of adapting to environments with tougher vegetation (Clarke, 2019; Crompton et al., 2022). As part of the broader Australopithecus genus, A. prometheus contributes to understanding the evolution of early hominins, particularly in relation to dietary and locomotor adaptations. This species, alongside others like A. afarensis, helps trace the complex environmental and evolutionary pressures that shaped early hominin development (Clarke & Kuman, 2019).

(Pinkstone, 2021)

Interesting Information

Habitat: Fossils of A. prometheus have been found in the Sterkfontein Caves, South Africa. This site indicates that the species lived in a mixed environment, with a combination of woodlands and open savannahs. Such an environment would have required adaptability in both arboreal and terrestrial behaviors. As such, it is likely that A. prometheus was capable of climbing trees when necessary but also moved effectively on the ground (Clarke, 2019).

Diet: The robust teeth and jaw musculature suggest a diet of tough, fibrous plant material, such as roots, tubers, and hard fruits or seeds. This dietary adaptation may have been an important factor in the species' survival, as it allowed A. prometheus to exploit ecological niches that other hominins could not.

Social Structure: While the details of A. prometheus’ social structure remain speculative, it is likely that this species lived in small social groups, as was typical of many early hominins. Cooperation in food gathering, protection, and possibly even in tool use (as evidenced by later species) would have been essential for survival (Dart, 1960).

The Silberberberg Grotto, looking west from the position of the eastern talus. The location of StW 573 is to the right of the person in the lower centre. Photo by Patrick Landman and Remi Benali. (Clarke 2018).

The discovery of A. prometheus and its unique physical traits provides crucial insights into the dietary and locomotor adaptations of early hominins. In his 1960 work, Dart discussed the bone tool-manufacturing abilities of australopithecines at Makapansgat, South Africa, which were once thought to be a human-exclusive trait. Dart's research demonstrated that early hominins were not only capable of creating tools but also used bones with intentionality and complexity (Dart, 1960). This challenges previous perceptions of early australopithecines as primitive, suggesting that behaviors like tool use and bone manipulation may have emerged earlier than previously thought.

MLD 1 (Makapansgat Limeworks Deposit 1)

The type speciment for Australopithecus prometheus is MLD 1 (Makapansgat Limeworks Deposit 1).

The type specimen for A. prometheus is MLD 1, a small fragment of occipital bone discovered by Raymond Dart in 1948 at Makapansgat, South Africa. Dart initially described the specimen as representing A. Prometheus. However, subsequent analysis revealed that the features of MLD 1 overlap significantly with those of A. africanus, leading some to question the validity of A. prometheus as a distinct species (Stratford 2021). Despite this, MLD 1 remains an important specimen in understanding the early hominin fossil record. Significance of MLD 1: Although it was the basis for Dart's initial classification of A. prometheus, MLD 1’s ambiguous features have led to debates about its role in defining the species. The lack of distinguishing traits between MLD 1 and A. africanus has prompted reevaluation, and many scholars now consider it as part of the broader A. africanus species complex (Stratford 2021).

MLD 1 Specimen (Hawks, 2022).

"Little Foot" (StW 573)

The StW 573 fossil is a nearly complete skeleton from Sterkfontein nicknamed "Little Foot".

The excavation of StW 573, known as “Little Foot,” has played a significant role in expanding our understanding of A. prometheus. The specimen, excavated at Sterkfontein in the 1990s, represents a nearly complete skeleton and offers a window into the locomotion and behavior of early hominins. The analysis of StW 573 suggests that A. prometheus had a highly adaptable locomotor system, capable of both terrestrial and arboreal movement. This flexibility points to an early hominin niche that was not confined to one specific environment, but instead spanned multiple terrains (Crompton et al., 2022). Key Features of StW 573: Evidence suggests that StW 573 was capable of walking upright on the ground, but also could engage in climbing and hand-assisted bipedality, offering insights into the species' ecological role (Clarke, 2019). The specimen challenges earlier models that likened early hominins to modern apes like chimpanzees, suggesting instead that they shared more in common with gorillas, particularly in their locomotor behaviors (Crompton et al., 2022).

The StW 573 skull, found in the Sterkfontein Caves, belongs to a mature individual and dates to around 3.67 million years ago, making it contemporary with Australopithecus afarensis fossils from East Africa. The skull has similar features to A. prometheus fossils from Sterkfontein and Makapansgat, especially in its cranial structure and teeth. This finding supports the idea that two species of Australopithecus, A. africanus and A. prometheus, coexisted in South Africa, with their fossil evidence showing they overlapped in time and space without necessarily competing with each other (Clarke et al., 2019).

"Little foot" is characterized as a climbing biped, with curved phalanges.

The skeleton as currently cleaned and reconstructed. Photo by Paul Myburgh. (Clark 2019)

The StW 573 skull in anterolateral view. Photo by M. Lotter. (Clarke et al., 2019)

References

Beaudet, A., Clarke, R. J., de Jager, E. J., Bruxelles, L., Carlson, K. J., Crompton, R., ... & Jashashvili, T. (2019). The endocast of StW 573 (“Little Foot”) and hominin brain evolution. Journal of Human Evolution, 126, 112-123.

Clarke, R. J. (2019). Excavation, reconstruction and taphonomy of the StW 573 Australopithecus prometheus skeleton from Sterkfontein Caves, South Africa. Journal of Human Evolution, 127, 41-53.

Clarke, R. J., & Kuman, K. (2019). The skull of StW 573, a 3.67 Ma Australopithecus skeleton from Sterkfontein Caves, South Africa. bioRxiv, 483495. doi:10.1101/483495

Crompton, R. H., McClymont, J., Elton, S., Thorpe, S., Sellers, W., Heaton, J., ... & Clarke, R. (2022). StW 573 Australopithecus prometheus: its significance for an australopith bauplan. Folia Primatologica, 92(5-6), 243-275.

Dart, R. A. (1948). The Makapansgat proto‐human Australopithecus prometheus. American Journal of Physical Anthropology, 6(3), 259-284.

Dart, R. A. (1953). The predatory transition from ape to man. International Anthropological and Linguistic Review, 1, 201-218.

Dart, R. A. (1960). The bone tool-manufacturing ability of Australopithecus prometheus. American Anthropologist, 62(1), 134-143.

John Hawks. (2024, January 21). Guide to australopithecus species. https://johnhawks.net/weblog/guide-to-australopithecus-species/

Robinson, J. T. (1954). The genera and species of the Australopithecinae. American Journal of Physical Anthropology, 12(2), 181-200.

Stratford, D., & Crompton, R. (2021). Introduction to special issue: a 3.67 ma Australopithecus prometheus skeleton from Sterkfontein caves, South Africa. Journal of Human Evolution, 158, 103008.

Taylor, I. by K., & Welker, B. H. (2017b, June 13). 14. Australopithecus Prometheus or africanus. The History of Our Tribe Hominini. https://milnepublishing.geneseo.edu/the-history-of-our-tribe-hominini/chapter/australopithecus-prometheus-or-africanus/

Tobias, P. V. (1997). Some little known chapters in the early history of the Makapansgat fossil hominid site. Paleontologica Africana, 33, 67-79.

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