Fossil hand from human-kin puzzles scientists match with human-like and gorilla-like features

Recently discovered fossils of an extinct human relative have baffled experts. Paranthropus bosi. They are amazed by the mixture of human-like and gorilla-like features in the fingers.

In the journal The natureresearchers describe a set of 1.5-million-year-old fossils from a site in Kenya that include the first obscure paranthropus bones identified in the fossil record. They are a very rare example of a relatively complete set of hand bones from this period.

The first specimen of Paranthropus was discovered in 1938 by Dr. Robert Broom in South Africa. Its name means “with man” and reflects the fact that it shared a direct ancestor with our own genus, Homo (known as Australopithecus), but with an early human lineage. Broom’s fossil belonged to the species Paranthropus robustus.

The species Paranthropus bosi, on the other hand, was first discovered in 1959 by Mary and Louis Leckie, in Oldovi Gorge, Kenya. His massive mandibles and teeth led to his nickname: The Nutcracker Man. Very molar teeth (where non-molar teeth take on the appearance of a molar) indicated a possible diet of tough and fibrous foods—certainly plant-based—that required extensive chewing.

Paranthropus was a bipedal hominin, like representatives of our own lineage, with a similar body size. It lived in similar habitats to early Homo. Yet it became extinct by 800,000 years ago. Inevitably, these two hominin lineages have been compared in every way possible to identify which traits ensured the survival of Homo. Homo’s persistence is attributed to its large brain, small teeth, and meat-based diet.

Paranthropus, on the other hand, with its large teeth and a small brain, is often cast as an evolutionary “also-ran”. However, there was little real evidence for concrete differences in how paranthropes used their bodies or their environments. Until now

New fossils from Kube Fura on the eastern shore of Lake Turkana, Kenya, show that Paranthropus bosi was not clumsy or poorly adapted to its lifestyle. The remains, dated to around 1.52 million years ago, include a partial skeleton with hand and foot bones along with an unformed pectoral jaw and teeth. For the first time, we can link the massive chewing apparatus of this species to the limbs and hands that helped work the ancient landscape.

Toes are, in many respects, more like gorillas than humans, but feet are very similar to Homo feet. In fact, the feet show that Pebocei was an efficient biped, walking on arched, stiff feet more similar to species that preceded our own, such as Australopithecus afarensis.

The big toe was attached to the others, and the joints show a single upward tilt—not dorsal canting. A twisted third metatarsal bone formed a transverse arch, an architectural feature that stiffens the human foot and turns it into a spring for energy-efficient movement.

The new find suggests a mix of both modern and ancient features. It paints a picture of a creature capable of crossing the mixed open habitats of East Africa on two legs, moving confidently between feeding areas and perhaps even carrying food or simple tools. The powerful hands may have been used for foraging for food, which required a strong grip.

There could be an argument that Paranthropus was pulling itself up into trees. Until now, paranthropus have not been thought of as climbers, nor as animals particularly associated with dense tree cover. It was thought that the cooler climate and thinner forests led to bipedalism in both Homo and paranthropus.

Yet there are clear differences with Homo. Peabody’s big toe was shorter than ours, suggesting a slightly different gait—perhaps a slower, heavier stride. The little finger was straighter and stiffer than that of apes, but not as well developed as that of Homo sapiens. This mosaic anatomy suggests that walking upright was already accomplished in several human relatives, even if each did it in its own way.

P. Bossi’s foot shows that by 1.5 million years ago, bipedalism was a common feature rather than a unique advantage. Both Homo and Paranthropus walked tall; Their evolutionary paths diverged not in locomotion but in lifestyle. While Homo relied increasingly on brainpower, tools, and cooperation, paranthropos doubled down on strength and chewing muscles. One lineage adapted to resilience, another to endurance – and in the end, only one survived.

But the discovery also softens the old story of triumph and failure. Paranthropus bosi was not a “failed” hominin relative. It was a successful species in its own right, having adapted to its ecological niche over millions of years. The new fossils remind us that human evolution was not a straight march of progress, but a branch of experimentation.

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