Homo Naledi's Bones Were Made For Walking … and Climbing

Peter Schmid and William Harcourt-Smith / Wits University
Peter Schmid and William Harcourt-Smith / Wits University

Its bones were made for walking—and for climbing, and possibly for tool making. That’s the latest insight to emerge from the ongoing analysis of Homo Naledi, our newest human relative, discovered in 2013 in the deep, nearly inaccessible Rising Star cave system in South Africa’s Cradle of Humankind. A pair of papers recently published in Nature Communications—one on the creature’s foot, and the other on the hand—paint a more detailed picture of these small-brained creatures.  

In the foot study, a team of researchers led by William Harcourt-Smith, a paleoanthropologist at Lehman College and a resident research assistant at the American Museum of Natural History, analyzed 107 bones from the foot of H. Naledi, including one nearly complete adult foot.

“The key finding is that this is a foot that is really, really human-like in most respects,” Harcourt-Smith told mental_floss. “However, in such a human-like foot, we did also find a couple of features that aren’t so human-like.”

He points to the creature’s slightly curved bones in its toes—a more primitive feature that may have been used to climb trees. It also seems to have had an arch that was quite low, which may have affected how it could have walked long distances on two legs, Harcourt-Smith says: “That in itself is quite interesting, because it points to how these animals were experimenting with walking upright. And, of course, bipedalism defines us as being human.”

A digital reconstruction of the H. Naledi foot. (a) Dorsal view. (b) Distal view of the cuneiforms and cuboid showing transverse arch reconstruction. (c) Medial view showing the moderate longitudinal arch. Image credit: Harcourt-Smith et al. in Nature Communications

In the hand study, a team lead by paleoanthropologist Tracy Kivell, of the University of Kent’s Skeletal Biology Research Centre, studied the near-complete hand (it’s missing one wrist bone known as a pisiform) of H. Naledi that was found with the bones still partially connected—an extraordinarily rare find. Some 150 hand bones were unearthed in the cave in all.

The 26 bones show a mix of characteristics that have never been seen before in any other hominin species, they say. The wrist bones have adaptive features that would’ve helped H. Naledi use tools (though none have been discovered) that are consistently found only in modern humans and Neanderthals. On the other hand, the finger bones are curved more than most australopiths—bipedal hominids like the 3.3-million-year-old Lucy—and very different from the straight fingers of humans and Neanderthals, which indicates the creature spent a good amount of time climbing.

The H. Naledi bones have yet to be dated, which means we don't know where they fit in among our hominid relatives. "Depending on how old (geologically) the H. naledi remains turn out to be, there will be important implications for interpreting the South African archaeological record, who made the various stone tools that have been found, and what anatomical adaptations were necessary to craft these implements," Kivell said in a statement sent to mental_floss.  

The hand of H. Naledi. (a) Palmar (left) and dorsal (right) views of the right hand bones, (b) found in situ in semi-articulation with the palm up and fingers flexed. The palmar surface of the metacarpals (Mc) and dorsal surface of the intermediate phalanges (IP) can be seen. Image credit: Kivell et al. in Nature Communications

When you put together the mostly modern foot and the modern-primitive hand with other features of the H. naledi body—especially the shoulder suited for climbing and a tiny skull that is decidedly un-human like in size—you get a picture of a creature that is utterly unlike anything else in the fossil record, Harcourt-Smith says. H. Naledi’s unique suite of characteristics “really speak to a unique experiment with being upright, with some part of the time spent being in the trees and some of the time walking around on the ground,” he says.

They’re not yet sure how the creature would have walked. “We haven’t come up with a really good model how it moved yet,” Harcourt-Smith says. “It’s a real conundrum. But I can tell you this: It would’ve spending most of its time walking upright. Its heel would’ve struck the ground the way ours does, and when it was walking it would’ve [looked] distinct from us—but not that much so.”

He continues, “What’s really interesting is that we always used to think with the genus Homo that one of the hallmarks of it was being a full upright, sort of obligate, 100 percent biped. But we now have a creature that we’ve assigned to Homo based on its feet and skull, and yet it’s not really walking upright 100 percent of the time. It raises as many questions as it answers about bipeds.”

Figuring out how H. naledi moved is one of the next big areas of inquiry for the foot researchers. “We really want to reconstruct the gait of this creature,” Harcourt-Smith says. “That means working with all of the teams and coming up with a really robust biomechanical evaluation of the whole. It’ll be a few years worth of work.”

They're also going to investigate the internal architecture, he says. “We’re going to be looking at the molecular structure, and that requires very high-resolution CT scanning.”

As for the hand, Kivell too will be peering inside. “We have done microCT scans of the hand bones and will next analyze the internal bony structure—trabecular and cortical bone—which can tell us more information about function and how the H. naledi hand was used,” she told mental_floss in an email.     

While the science continues, the scientists themselves seem to still be riding the high of the discovery of this unprecedentedly large assemblage of unique bones, and excited by what they can teach us about our evolutionary past.

“When I got down there, it was fossil heaven,” Harcourt-Smith says. “There were so many different things. You never get these sort of opportunities with this amount of stuff found so quickly, and it really was an extraordinary privilege to work on. It’s not normal to get this sort of treasure trove of material in one go. It’s new territory in some ways.”

26 Fascinating Facts About Fossils

Mental Floss via YouTube
Mental Floss via YouTube

If you’ve never visited the Big Bone Room, you’re in luck. Check out our visit to New York City's American Museum of Natural History for a rundown on fossils, which provide invaluable insight into our understanding of history and its once-living occupants.

In this edition of "The List Show," editor-in-chief Erin McCarthy explains the ins and outs of excavation, fossil follies (extinct giants were a big miss), and the terrorizing prospect of a 3-foot-tall parrot.

For more episodes like this one, be sure to subscribe here!

2000-Year-Old Roman Tweezers and Metal Ear Swab Discovered in UK

Christopher Furlong/Getty Images
Christopher Furlong/Getty Images

The ancient Romans took hygiene seriously. They pioneered indoor plumbing, deodorant, and the practice of bathing daily. A recent discovery made at a bridge construction site in the UK reinforces just how committed to cleanliness the Roman civilization was. As Geek.com reports, workers unearthed an ear cleaner and a pair of tweezers thought to date back 2000 years to the Roman Empire.

The artifacts were dug up by the Ebbsfleet Development Corporation at the location of the new Springhead Bridge in Ebbsfleet Garden City, a development in Kent. One small tool appears to be designed for pinching and plucking small items just like modern-day tweezers. The other object is thought to have been built for cleaning ears—but instead of cotton, the "swab" is made entirely of metal. They're thought to date back thousands of years, but scientific analysis will need to be done to determine the exact age.

Grooming items weren't the only artifacts uncovered at the site. Workers also found a piece of timber believed to have been meant for an ancient structure. The Ebbsfleet River, where the new bridge is being built, was once a shipping hub and a Roman settlement called Vagniacis. Historical finds are so common in the area that the Ebbsfleet Development Corporation employs full-time archaeologists.

The personal hygiene tools have been removed from the archaeological site by experts who will study them to learn more about their origins. The fate of the artifacts is unclear, but the construction company behind the discovery hopes they can remain in the same city where they were found.

[h/t Geek.com]

SECTIONS

arrow
LIVE SMARTER