Paranthropus robustus, a thoroughly documented hominin lineage, has thus far lacked any reported genetic substantiation. This species inhabited the region presently known as South Africa approximately two million to 1.2 million years ago. In a recent investigational effort, paleoanthropologists successfully extracted enamel protein sequences from 2-million-year-old dental remains attributed to this hominin, recovered from the Swartkrans fossil site in South Africa. Their discoveries indicate a greater degree of internal variation within the Paranthropus genus than was previously appreciated, lending support to the hypothesis that multiple distinct species may have existed within this group.
Paranthropus boisei. Image credit: © Roman Yevseyev.
While advancements in ancient DNA (aDNA) sequencing have yielded significant insights into the evolutionary connections of hominins from the Middle to Late Pleistocene epochs, our comprehension of earlier Pliocene-Pleistocene species, such as Paranthropus, remains somewhat restricted.
This limitation stems primarily from the poor preservation of aDNA in African hominin fossils exceeding 20,000 years in antiquity.
Historically, Paranthropus has been conceptualized as a singular evolutionary entity.
However, the confluence of shared characteristics between Paranthropus robustus and Australopithecus africanus has prompted inquiries into their potential ancestral relationship.
Furthermore, observed discrepancies in dental morphology suggest either latent diversity within the Paranthropus robustus classification or the existence of several discrete species.
In the contemporary research initiative, Dr. Palesa Madupe, affiliated with the University of Copenhagen and the University of Cape Town, alongside her colleagues, employed ancient proteins – which exhibit considerably greater longevity – as a means to probe the variations present within this ancient hominin species.
Utilizing cutting-edge high-resolution mass spectrometry and paleoproteomics methodologies, the research team meticulously analyzed dental enamel proteins from four Paranthropus robustus fossil specimens unearthed at Swartkrans Cave.
These fossils, estimated to date from 2.2 to 1.8 million years ago, represent some of the earliest known examples of this hominin.
The examination of protein sequences brought to light molecular-level discrepancies among the Paranthropus robustus individuals. This analysis included evidence pointing to the presence of both male and female specimens, thereby challenging the efficacy of tooth size as a sole determinant for sex determination and positing that sexual dimorphism alone cannot adequately explain the variability observed in the fossil record.
Significantly, one particular individual appears to be genetically differentiated from the others, a finding that could signify the presence of a distinct Paranthropus lineage or reflect pronounced intraspecific variability.
These findings resonate with recent morphological evidence that indicates previously unacknowledged taxonomic differentiation within the genus, including the proposed species Paranthropus capensis.
“Our investigation effectively illustrates how paleoproteomics can be instrumental in differentiating between sexual dimorphism and other sources of variation in early African hominins of the Pleistocene epoch,” the researchers stated in their conclusion.
This research has been officially published in the esteemed scientific journal, Science.
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Palesa P. Madupe et al. 2025. Enamel proteins reveal biological sex and genetic variability in southern African Paranthropus. Science 388 (6750): 969-973; doi: 10.1126/science.adt953
