Jan Bartek – AncientPages.com – Paranthropus robustus was a prehistoric human species that inhabited South Africa around 2 million years ago, coexisting with Homo ergaster, a direct ancestor of modern humans. The Swartkrans Cave, located between Johannesburg and Pretoria, has been a rich source of Paranthropus robustus fossils since scientific excavations began in 1948. These findings have provided significant insights into this extinct species’ diet and social structure.
A fossil leopard lower jawbone next to a skull fragment of a juvenile Paranthropus robustus. Note the two punctures in the skull, which match the spacing of the tips of the leopard’s fangs—implying that this unfortunate hominin was killed and eaten by a leopard. Credit: Jason Heaton
The species’ heavy jaws and thickly enameled teeth indicate an ability to consume tough, low-quality foods during scarce times. Additionally, the variation in skull and tooth size suggests sexual dimorphism with larger males and smaller females, pointing to a polygynous mating system where one dominant male mates with multiple females.
However, our understanding of Paranthropus robustus’s physical attributes, such as stature, posture, and movement, has been limited due to the scarcity of skeletal remains beyond skulls and teeth. A recent discovery at Swartkrans—a set comprising an articulating hipbone, thigh bone, and shin bone—promises to enhance our knowledge about how this species moved and interacted within its environment.
A team of international researchers affiliated to the Evolutionary Studies Institute at the University of the Witwatersrand (Wits University) in South Africa, including Travis Pickering, Matthew Caruana, Marine Cazenave, Ron Clarke, Jason Heaton, A.J. Heile, Kathleen Kuman, and Dominic Stratford, has discovered that this group of fossils belongs to a single, young adult Paranthropus robustus.
The fossil provides evidence that the species was a habitual upright walker, similar to modern humans. Additionally, it confirms that the species was extremely small in size.
“It is estimated that this individual, probably a female, was only about a meter tall and 27 kg when it died, making it even smaller than adults from other diminutive early human species, including those represented by the famous ‘Lucy’ (Australopithecus afarensis, about 3.2 million years old) and ‘Hobbit’ (Homo floresiensis, about 90,000 years old) skeletons, from Ethiopia and Indonesia, respectively,” says Professor Pickering from the University of Wisconsin–Madison, who led the research.
The small stature of the newly discovered Paranthropus robustus individual likely made it more susceptible to predators, including sabertooth cats and giant hyenas, known inhabitants of the Swartkrans Cave region. This hypothesis is supported by the team’s analysis of surface damage on the fossils, which revealed tooth marks and chewing patterns consistent with those left by leopards on their prey’s bones.
“Although it seems that this particular Paranthropus robustus individual was the unfortunate victim of predation, that conclusion does not mean that the entire species was inept. We know that Paranthropus robustus survived in South Africa for over a million years and is found invariably, and at various sites, in spatial association with stone and bone tools,” says Pickering.
These tools served multiple functions, such as butchering animals for meat and excavating edible roots and underground insects. Current research is exploring whether Paranthropus robustus, the contemporaneous Homo ergaster, or both species were responsible for creating and using these essential implements.
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The Swartkrans team leans towards the likelihood that Paranthropus robustus had both the cognitive and physical abilities to perform these tasks. Their ongoing study of fossils involves CT-scan analyses of internal bone structures, which aim to provide further insights into the growth and developmental patterns of Paranthropus robustus, while also enhancing our understanding of its locomotor behaviors.
The study was published in the Journal of Human Evolution
Written by Jan Bartek – AncientPages.com Staff Writer
