Newly Discovered Human Ancestor's Feet And Hands Were Strikingly Similar To Our Own

Peter Schmid/Will Harcourt-Smith.

The newly discovered human, Homo naledi, is special in so many ways. Likely having roots at the base of our very own genus, homo, this mesmeric yet controversial species is arguably one of the most significant human ancestor finds to date. But despite the bounty of information already accrued, our learning journey for this truly unique species is far from over. Two new papers are evidence of that, dedicated entirely to the hand and foot of this hominin.

Both described in Nature Communications, it’s no great surprise that studies are still pouring out; after all, scientists have had more than 1,600 fossil fragments from a single site – the Rising Star cave system in South Africa – to sink their metaphorical teeth into. Among this scattering of bones, representing infants through to the elderly, was an almost complete adult right hand, looking like it was an a “death grip,” Marina Elliott, one of the excavators who was not involved in the present study, told IFLScience.

Like much of H. naledi’s skeleton, this hand seems to sport an unusual combination of primitive and more evolved, transitional features. For example, the long sturdy thumb and wrist architecture are similar to those found in Neanderthals and modern humans, allowing for more precise object manipulation, such as tool use.

On the other hand (pun intended), the fingers show curvature to a similar or greater extent than some of the earliest hominins; perfect for gripping. This combination of human-like wrist and palm with more primitive fingers suggests that H. naledi was a climber, using the strong grasp to maneuver along and suspend from tree branches.

But even though this bipedal species had hands suitable for locomotor climbing, the lower limbs tell us that it was also a long-distance walker. Analyzing more than 100 foot bones, including one nearly complete adult foot, scientists once again found striking similarities to modern human feet, not only in structure but possibly also function. Notably, the foot is arched and would contact the ground in a similar manner to our own as we walk, and the big toe is not adapted for grasping. Although the foot is perhaps the most human-like of our ancestors to date, there are subtle differences: the toes are more curved, for example, and the arch is not as prominent as our own.

H. naledi also had extremely long legs and an outward flaring pelvis, more so than the famous 3.2-million-year-old hominin Lucy, which likely predates this species, although dating has yet to be carried out on the latest find.

“This configuration moved the hip muscles away from the hip joints and gave them more leverage in walking, perhaps more of an advantage than humans have today,” lead researcher Jeremy DeSilva said in a statement. “Over time, the architecture of the pelvis evolved and expanded to allow the birth of larger-brained babies.”

The intriguing mixed bag of primitive and more modern features is part of what makes H. naledi so strikingly unique, a species that is gradually helping us understand the early history of our own genus. 

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