Researchers analysed 2 million-year-old Paranthropus robustus teeth from South Africa, uncovering ancient proteins that reveal new genetic clues about early human diversity and evolution.
For nearly a hundred years, scientists have been trying to understand the remains of Paranthropus robustus, an ancient relative of early humans. This species, which walked upright, lived in southern Africa between 2.25 and 1.7 million years ago. It had strong jaws and thick-toothed enamel, which helped it chew tough foods like roots and nuts, a trait that evolved to help it survive in a tough environment.
Tracing Our Ancient Roots
Southern Africa is one of the best places in the world for finding fossils that show different stages of human evolution. Fossils of Australopithecus africanus, A. sediba, and A. prometheus show early forms of walking on two legs, while later species such as Homo habilis, Homo erectus, Homo naledi, and finally Homo sapiens reveal the development of tool-making and larger brains. Together, these discoveries show an amazing journey of evolution that led to the appearance of modern humans in South Africa about 153,000 years ago. However, many questions about P. robustus remain, especially how it fits into the broader picture of human evolution.
Decades of Unanswered Questions
When P. robustus fossils were first discovered in 1938, scientists were fascinated. Finding answers has been difficult because ancient DNA rarely survives in Africa’s warm climate, making genetic evidence scarce. To overcome this, a team of African and European researchers used a new method called paleoproteomics, which studies ancient proteins that can survive for millions of years.
Ancient Proteins Tell a New Story
The scientists studied proteins from the enamel of four P. robustus teeth found in Swartkrans Cave, part of South Africa’s famous Cradle of Humankind. Unlike DNA, proteins stick tightly to enamel and bone, which helps protect them from heat and decay. By analyzing these proteins, the researchers could determine the sex of each fossil, two males and two females, and find small genetic differences.
They also discovered a protein called enamelin, which is involved in tooth enamel formation. Two fossils showed a sequence found in humans, chimpanzees, and gorillas, while the other two had a version unique to Paranthropus. Even more interestingly, one fossil had both versions, offering the first evidence of genetic variation (called heterozygosity) in a molecule that is over two million years old.
Rethinking the Human Family Tree
These findings challenge the idea that P. robustus was a single, uniform species. The genetic differences suggest that there may have been different populations, perhaps even separate lineages that interbred or evolved separately. By using this molecular data with traditional fossil analysis, scientists can now create a more detailed picture of how early human relatives were connected. Future research will explore this further by examining other P. robustus fossils across South Africa to see how widespread these differences were.
As technology in paleoproteomics continues to improve, even older and more fragile fossils may soon reveal their secrets. The mystery of Paranthropus robustus now appears far more complex, offering exciting clues about the diversity and adaptability of our ancient ancestors.
Source: The Conversation. “2 million-year-old teeth reveal secrets from the dawn of humanity.” ScienceDaily. ScienceDaily, 1 November 2025.