For decades, scientists have debated whether Paranthropus boisei, an extinct human relative recognized for its robust jaws and large teeth, could make and use stone tools. New research published in Nature presents the first hand and foot bones definitively linked to this species, revealing that P. boisei possessed both human-like dexterity and strong gripping ability similar to gorillas.
“This is the first time we can confidently link Paranthropus boisei to specific hand and foot bones,” said Carrie S. Mongle, a paleoanthropologist and assistant professor of anthropology at Stony Brook University, who led the study. “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 of Homo sapiens, with divergence from a common ancestor estimated at over 3 million years ago. Until now, fossil evidence for P. boisei has mostly consisted of skulls and teeth, limiting researchers’ understanding of its movement or tool use capabilities.
The newly described partial skeleton, named KNM-ER 101000, was excavated between 2019 and 2021 at Koobi Fora near Lake Turkana in Kenya from geological layers dating back just over 1.5 million years. The discovery included cranial fragments, teeth, and well-preserved 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.
Previously, fossils from Homo and Paranthropus were sometimes found at the same sites, but stone tools were generally attributed only to Homo. The new fossils suggest that P. boisei had hand proportions suitable for manipulating stone tools but lacked certain wrist features seen in later humans and Neanderthals.
“There has been a long controversy about whether or not this species made and used stone tools,” said Matt Tocheri, a co-author from Lakehead University in Canada. “This fossil evidence effectively ends that debate.”
The findings also add detail to discussions about early hominin ecology. Early Homo species seem to have become more dependent on tool use, while Paranthropus maintained a diet focused on plant foods—an idea supported by their facial, dental, jaw, and now hand adaptations.
“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 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 explained. “And these powerful grasping abilities would also have been quite useful for climbing.”
Louise Leakey, director of the Koobi Fora Research Project, highlighted the importance of long-term fieldwork and 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.”
Leakey also acknowledged local community partners’ essential role in supporting ongoing exploration in the Turkana Basin.
The research was funded by organizations including the National Geographic Society and the Stony Brook Research Foundation. The study involved researchers from several institutions such as the Turkana Basin Institute, National Museums of Kenya, Koobi Fora Research Project, Stony Brook University, University of Colorado, Lakehead University, Washington University in St. Louis, Rutgers, University of Southern California, and the American Museum of Natural History.