Paleoanthropologists have unearthed and examined a hominin partial skeleton that includes hand and foot bones unambiguously associated with skull elements of Paranthropus boisei, a species of early hominin that lived in East Africa between 2.3 and 1.2 million years ago. Their findings demonstrate that Paranthropus boisei shared key manipulative and bipedal adaptations with the genus Homo. Moreover, the hand morphology of the species converges on that of gorillas in ways that are consistent with manual food processing and would have facilitated powerful grasping, such as that used in climbing.
Paranthropus boisei. Image credit: © Roman Yevseyev.
It has long been assumed that the earliest members of the genus Homo manufactured and used stone tools.
However, the discoveries of 3.3 million-year-old stone tools at Lomekwi together with 3-million-year-old Oldowan artifacts alongside a Paranthropus tooth at Nyayanga, both sites in Kenya, have reignited debate about possible tool use in other species.
“When Mary Leakey discovered the OH 5 cranium of Paranthropus boisei alongside Oldowan stone artifacts, it was declared ‘the oldest yet discovered maker of stone tools’,” said Dr. Carrie Mongle of Stony Brook University and colleagues.
“Whether Paranthropus made and used tools has been debated ever since, largely because there are no known hand bones that can be definitively attributed to this genus.”
In the new study, the authors examined a partial hominin skeleton recovered between 2019 and 2021 at Koobi Fora on the eastern side of Lake Turkana, Kenya.
Named KNM-ER 101000, the specimen is estimated to be slightly older than 1.52 million years.
The teeth and skull of the specimen match those of previously documented Paranthropus boisei fossils.
“KNM-ER 101000 includes the first hand and foot bones unambiguously associated with the teeth and skull of Paranthropus boisei,” the researchers said.
The hands of KNM-ER 101000 share features with both modern humans and African apes.
For example, the thumb-finger length proportions indicate that Paranthropus boisei had similar grip or dexterity to humans, but possibly without precision pinch grips.
By contrast, other hand bones resemble those of gorillas, which may have given Paranthropus boisei a powerful grip that could have been useful for climbing.
“The findings suggest that Paranthropus boisei was capable of tool making and use in some capacity while also supporting the proposed dichotomy of distinct dietary adaptations between Paranthropus and Homo,” the scientists said.
“In addition to offering insights into the poorly known postcranial functional anatomy of Paranthropus, this discovery illuminates broader patterns of hominin hand evolution and tool use.”
The findings were published in a new paper on October 15 in the journal Nature.
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C.S. Mongle et al. New fossils reveal the hand of Paranthropus boisei. Nature, published online October 15, 2025; doi: 10.1038/s41586-025-09594-8
