Digital reconstruction of iconic fossil reveals unexpected similarities with Ethiopian specimens, contributing to debates on early hominin relationships.
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The digital reconstruction of the iconic fossil, Little Foot, reveals unexpected similarities with Ethiopian specimens, contributing to debates on early hominin relationships.
view moreCredit: Amelie Beaudet/Wits University
A new digital reconstruction of the face of the 3.67‑million‑year‑old Australopithecus fossil, Little Foot, provides new insight into the evolution of the human face.
The new findings, published in Comptes Rendus Palevol, offer fresh insight into the diversity of the fossil hominin (i.e., extant human and their ancestors and relatives) face across Africa 4-3 million years ago.
Little Foot was discovered at the Wits Sterkfontein Caves, located about 40km North West of Johannesburg, South Africa, in the Cradle of Humankind World Heritage Site. It is the most complete early hominin skeleton ever found. While much of the skeleton has been, and continues to be, studied, the face has been distorted by millions of years of geological processes that were impossible to correct using physical reconstruction methods. Using high‑resolution synchrotron scanning at the Diamond Light Source synchrotron in the UK and advanced virtual reconstruction techniques, an international research team led by Dr. Amelie Beaudet and Professor Dominic Stratford has now digitally reassembled the facial bones, producing one of the most complete Australopithecus faces known.
The team analysed nine linear facial measurements and applied three‑dimensional geometric morphometrics to compare Little Foot to those of several other extant great apes as well as with three other Australopithecus fossils. These included a younger specimen from South Africa and two Ethiopian specimens. The results show that the overall size of the face, the shape and dimensions of the eye sockets, and the general facial architecture of Little Foot more closely resemble the East African fossils than the younger South African comparative specimen, although the study is limited to a couple of fossil specimens due to the scarcity of complete faces.
“This pattern is unexpected, given the geographic origin of Little Foot and suggests a more dynamic evolutionary history than previously assumed,” says Beaudet, a previous post-doctoral fellow and current honorary researcher of Wits University. Little Foot, for instance, may represent a lineage closely related to East African populations, while later South African hominins developed more distinct facial features through local evolutionary processes.
The study also identified evidence of selective pressures acting on the orbital region (the eyes), which may relate to changes in visual capacity and ecological behaviour.
“Besides the fact that our study, limited to one anatomical region and a couple of comparative fossil specimens, provides additional data on the affinities between Australopithecus populations across Africa, we demonstrate that the orbital part of the face has possibly been under evolutionary pressure at that time,” says Beaudet.
“While we know that the hominin face evolved through time to become less projected and more gracile, we still ignore when such changes occur, and the nature of the evolutionary mechanisms involved.”
“Rather than viewing early hominin evolution as occurring in isolated regions, the study supports the idea of Africa as a connected evolutionary landscape, with populations adapting to ecological pressures while remaining linked through shared ancestry,” says Stratford, who is also Director of Research at the Wits Sterkfontein Caves.
Through digestive, visual, respiratory, olfactory, and non-verbal communication systems, the face plays a central role in the interactions primates have with their physical and social environments. In this context, the face is a key anatomical region for understanding how the hominins adapted to, and engaged with, their surroundings.
“Only a handful of Australopithecus fossils preserve an almost complete face, making Little Foot a rare and valuable reference point. Little Foot’s face preserves key anatomical regions involved in vision, breathing and feeding, and its skull will offer further key elements for understanding our evolutionary history,” says Beaudet.
As further virtual reconstructions are completed, the researchers hope to refine our understanding of how early hominins moved, interacted and diversified across Africa.
“The face is only part of the story. Other parts of the skull, especially the braincase, remain distorted by plastic deformation and will require similar digital reconstruction to better understand brain size and organisation in this early hominin,” says Beaudet.
Journal
Comptes Rendus Palevol
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