For the first time, researchers have linked specific hand and foot bones to Paranthropus boisei, an extinct human relative. The findings, published in Nature, provide new insights into the evolution of tool use and upright walking among early hominins.
Dr. Carrie S. Mongle, a paleoanthropologist and Assistant Professor of Anthropology at Stony Brook University, led the study. She said, “This is the first time we can confidently link Paranthropus boisei to specific hand and foot bones. The hand shows it could form precision grips similar to ours, while also retaining powerful grasping capabilities more like those of gorillas, and the foot is unquestionably adapted to walking upright on two legs.”
Paranthropus is considered an evolutionary cousin to Homo sapiens, diverging from a common ancestor over three million years ago. Until now, most fossil evidence for P. boisei consisted of skulls and teeth, making it difficult for scientists to determine how the species moved or whether it could make and use tools.
Fossils of Homo and Paranthropus are sometimes found together at archaeological sites. Historically, stone tools found at these sites have been attributed to Homo species rather than Paranthropus.
The partial skeleton described in this study—KNM-ER 101000—was found at Koobi Fora near Lake Turkana in Kenya between 2019 and 2021. It dates back more than 1.5 million years and includes cranial fragments, teeth, and a well-preserved set of hand and foot bones.
“It took a huge amount of time to carefully remove the sediments that ultimately revealed these amazing fossils,” said Cyprian Nyete, Field Director of the excavations.
Dr. Matt Tocheri of Lakehead University, a co-author, commented, “There has been a long controversy about whether or not this species made and used stone tools. This fossil evidence effectively ends that debate.”
Analysis of the new fossils shows that P. boisei had hand proportions similar to early Homo species, suggesting they could manipulate stone tools. However, they lacked certain wrist features seen in later humans and Neanderthals.
The findings also highlight differences in ecological roles among early hominins. Early Homo species seem to have relied more on tool use, while Paranthropus had specialized adaptations for eating plant foods.
“This discovery helps us understand a lot more about Paranthropus boisei, especially how its hand shared similarities with members of our own genus Homo while evolving its own capabilities,” said Dr. Caley Orr from the University of Colorado School of Medicine. “It has converged on gorilla morphology in ways that are consistent with obtaining and processing tougher plant foods with its hands,” he added, “and these powerful grasping abilities would also have been quite useful for climbing.”
Dr. Louise Leakey, Director of the Koobi Fora Research Project, noted the importance of collaboration: “Overall, this discovery is a great example of how much we can achieve when we undertake long-term fieldwork that involves strong collaborations between researchers from around the world and the local communities that live in the places where hominin fossils are preserved.” She emphasized the role of local partners who spend most of the year excavating and surveying in the region.
Leakey also reflected on her family's history in paleoanthropology: “It is definitely an exciting new era in paleoanthropology, which has changed and grown so much since my grandparents [Louis and Mary Leakey] discovered the first skull of Paranthropus boisei at Olduvai and my parents [Richard and Meave Leakey] first began to focus their research on the fossil-rich Turkana Basin in Kenya.”
Funding for this research came from the National Geographic Society and Stony Brook Research Foundation. The study was conducted by an international team including members from institutions such as Stony Brook University, National Museums of Kenya, University of Colorado, Lakehead University, Washington University in St. Louis, Rutgers University, University of Southern California, American Museum of Natural History, Turkana Basin Institute, and Koobi Fora Research Project.