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.”

13 Facts About the Chauvet Cave Paintings

A view taken on June 13, 2014 shows paintings of animal figures on the rock walls of the Chauvet Cave in Vallon Pont d'Arc.
A view taken on June 13, 2014 shows paintings of animal figures on the rock walls of the Chauvet Cave in Vallon Pont d'Arc.
Jeff Pachoud, AFP/Getty Images

Discovered by accident in 1994, the cave paintings adorning the walls of Chauvet Cave in France are among the oldest and most beautiful figurative art in human history. About 36,000 years ago, the ancient artists drew lifelike beasts that seem to gallop, crawl, and frolic through the cave’s chambers. In one stunning triptych, 50 drawings of horses, lions, and reindeer cavort across 49 feet of limestone wall. The cave paintings even impressed filmmaker Werner Herzog enough to make a documentary (available on Netflix). Here are a few more facts about the Chauvet Cave paintings.

1. The Chauvet Cave paintings were discovered by three local explorers.

It was December 18, 1994. French cavers Jean-Marie Chauvet, Éliette Brunel Deschamps, and Christian Hillaire had spent the day exploring the Pont d’Arc caves in the Ardèche region in southern France. They came upon an array of fallen rocks and noticed a gentle woosh of air from beneath the rock pile. Prying aside the stones, they found an aperture and dropped down into a large chamber with a high ceiling that appeared to branch off into other chambers. Their headlamps illuminated several handprints and a red ochre painting of a mammoth on the wall of one chamber. At that moment, they knew they had stumbled onto a major archaeological discovery.

2. Chauvet Cave was formed by an underground river.

Replica of the Chauvet Cave paintings
A detail of the full-scale reproduction of frescos found at the cave of Pont-D'Arc, also known as the Chauvet Cave, on April 8, 2015 in Vallon Pont D'Arc. The frescos were reproduced by French graphic artist and researcher Gilles Tosello to replicate the Chauvet Cave, which is located in the Ardèche region of southern France.
Jeff Pachoud, AFP/Getty Images

Subterranean rivers flowing through the area's limestone hills created Chauvet Cave, along with hundreds of other gorges and caverns in the Ardèche. Chauvet Cave is about 1300 feet (roughly a quarter-mile) long with 14 chambers branching off the largest room, the Chamber of the Bear Hollows—the first one discovered by Chauvet, Brunel Deschamps, and Hillaire. This chamber, closest to the entrance, features no cave paintings; flooding is thought to have washed away any artwork. The most decorated vestibules are farthest from the entrance and include the Hillaire Chamber, Red Panels Gallery, Skull Chamber, the Megaloceros Gallery, and the End Chamber.

3. The Chauvet Cave painters were Aurignacians.

Aurignacians, the first anatomically modern humans in Europe, lived during the Upper Paleolithic, or Old Stone Age, between 46,000 and 26,000 years ago. (Aurignacian also refers to this time period.) Aurignacian culture is characterized by the first figurative drawings and carvings, the invention of a flaked stone tool called a burin used for engraving, bone and antler tools, jewelry, and the oldest-known musical instruments.

In addition to the Chauvet Cave paintings, Aurignacian animal and human figurines have been found in other parts of Europe. At the Hohle Fels cave in southwestern Germany, archaeologists discovered the oldest known Venus statuette, dating from 40,000 to 35,000 years ago, and some of the oldest known bone flutes from the same time period. In Southeast Asia, a cave in Borneo bears the oldest known figurative painting, created at least 40,000 years ago.

4. Ancient humans visited Chauvet Cave during two separate millennia.

A reproduction of a hand stencil found in Chauvet Cave
Picture taken on October 12, 2012 in Vallon-Pont-d'Arc of the facsimile of the Chauvet cave.
Jeff Pachoud, AFP/Getty Images

According to paleontologist Michel-Alain Garcia in Chauvet Cave: The Art of Earliest Times, radiocarbon dating of organic materials in Chauvet Cave suggest people used the cave during two different time periods. In the first, about 36,500 years ago during the Aurignacian, artists drew the majority of the Chauvet Cave paintings. They brought wood into the cave and burned it to create light and charcoal for drawing. Then, for an unknown reason, the Aurignacians abandoned the cave for about five or six thousand years, and it was taken over by cave bears. In the second instance of human use, about 31,000 to 30,000 years ago in the Gravettian period, humans left behind footprints, scorch marks from torches, and charcoal, but no artwork.

5. Fourteen animal species are represented in the Chauvet Cave paintings.

The most common animals in the Chauvet Cave paintings are cave lions, mammoths, and woolly rhinoceroses; all coexisted with the Aurignacians in Europe, but are now extinct. Along with depictions of cave bears, the four species make up 65 percent of the species in the paintings. The other are bison, horses, reindeer, red deer, ibex, aurochs (an extinct wild ancestor of domesticated cattle), the extinct Megaloceros deer (also called the Irish elk or giant deer), musk ox, panthers, and an owl. The paintings are notable for depicting not just figurative representations of the animals, but actual scenes that reveal the animals’ real behavior—like two woolly rhinoceroses butting horns, and a pride of lions stalking a group of bison.

6. Non-animal themes also pop up in Chauvet Cave paintings.

Palm prints in red paint found in Chauvet Cave
A view taken on June 13, 2014 shows paintings on the rock walls of the Chauvet cave, in Vallon Pont d'Arc.
Jeff Pachoud, AFP/Getty Images

In the middle chambers of Chauvet Cave, several walls and overhanging rocks are decorated with red dots made by human palms and stencils of human hands. In the farthest galleries of the cave, five triangular representations of a woman’s pubic area are scratched on to the walls, and one picture of a woman’s lower body similar in profile to Paleolithic Venus figurines is drawn on a stalactite-like rock pendant. Anthropologists are not sure what they’re meant to symbolize.

7. A prehistoric child’s footprints were discovered in Chauvet Cave.

A single track of footprints measuring 230 feet long was found in the soft clay floor of the cave’s Gallery of the Crosshatching. Researchers analyzed modern European feet that were estimated to be roughly equivalent to those of European Early Modern Humans and determined that the track was probably made by a young boy about 4.5 feet tall. Scientists were able to date the prints based on the marks left by a burning torch on the roof of the gallery. “The child regularly wiped his torch on [the vault] above his path. These charcoal marks, dated to 26,000 years ago, seem to have been placed contrary to the direction of progress on purpose, as if to mark the way back,” Garcia writes. Two bits of charcoal were retrieved from the substrate and dated to a period between 31,430 years and 25,440 years ago.

8. The child might have had a pet dog.

The adolescent boy’s footprints are near those of a large canid—possibly a wolf. When Garcia took a closer look, he noticed the length of the middle digit was shorter than a wolf’s, a trait more typical of a domesticated dog. But in the 1990s, when Garcia made the find, the oldest undisputed fossil evidence of a domesticated dog dated back only 14,200 years before present.

A 2017 study that built on previous research, however, compared genomes of three Neolithic dogs with those of more than 5000 canines, including modern wolves and dogs. The researchers concluded that dogs and wolves split genetically sometime between 41,500 and 36,900 years ago, and a second divergence of eastern and western dogs occurred between 23,900 and 17,500 years ago. That puts the window of domestication between 40,000 and 20,000 years ago—the same time as the Aurignacian child and his very good boy were walking through Chauvet Cave.

9. Chauvet cave provided shelter for bears.

Outline of a cave bear head in Chauvet Cave
A view taken on June 13, 2014 shows paintings on the rock walls of the Chauvet cave, in Vallon Pont d'Arc.
Jeff Pachoud, AFP/Getty Images

Larger than modern grizzlies, cave bears spent winters in Chauvet Cave for thousands of years before humans began painting in it. They left claw scratches on the walls and dozens of tracks and footprints in the floor. In the Chamber of the Bear Hollows, researchers have found more than 300 hollows (sleeping spots that bears wore into the cave floor) and dozens of bear tracks and paw prints, made after humans stopped visiting the cave. About 2500 cave bear bones and 170 skulls were scattered throughout the cave’s main chambers. When scientists first investigated the cave in the mid-1990s, they found a cave bear skull carefully placed on a large stone in the middle of a deep chamber, in a way that only humans could have done.

10. The cave also provided shelter for a lot of wolves.

The floor of the Brunel Chamber, directly south of the Chamber of the Bear Hollows, showed multiple wolf prints that indicated a large number of “fissipeds” (pad-footed carnivores) had trampled the ground. Bear prints were superimposed on the wolf prints, suggesting that the bears came in after the wolves.

Not only large carnivores occupied the cave—judging from the variety of bones, it was practically a prehistoric zoo. In addition to the wolf, ibex, and bear bones, prehistorian Jean Clottes reported finding those of foxes, martens (a kind of weasel), roe deer, horses, birds, rodents, bats, and reptiles. And, yes, he also found fossilized wolf poop, indicating the wolves probably went into the cave in search of carrion.

11. No one knows why the Chauvet Cave paintings were created.

Chauvet Cave paintings
A detail of the full-scale reproduction of frescos found at the cave of Pont-D'Arc also known as the Chauvet cave, on April 8, 2015 in Vallon Pont D'Arc. The frescos were reproduced by French graphic artist and researcher Gilles Tosello to replicate the Chauvet Cave, located in the Ardèche region of southern France.
Jeff Pachoud, AFP/Getty Images

The purpose behind the Chauvet Cave paintings is a mystery, but some characteristics of the artwork may offer clues. Researchers have noted that the primary species depicted—cave bear, lion, mammoth, and rhinoceros—were not prey species that Aurignacians pursued for food, possibly suggesting that the paintings weren’t meant to ensure bountiful hunting.

A 2016 study hinted that the Chauvet Cave artists may have been recording contemporary events. Jean-Michel Geneste and colleagues proposed that a spray-like design in the Megaloceros Gallery was a faithful depiction of a volcanic eruption that occurred in the nearby Bas-Vivaris region between 40,000 and 30,000 years ago. If that is true, Chauvet Cave boasts the oldest known painting of volcanic activity, smoking the previous record holder—a 9000-year-old mural in central Turkey—by 28,000 years.

12. When Werner Herzog entered Chauvet Cave, he was overwhelmed.

Filmmaker Werner Herzog accompanied researchers into the depths of the cave system to make his 2010 documentary Cave of Forgotten Dreams (available to stream on Netflix). Herzog’s grandfather was an archaeologist, and Herzog himself once earned money as a ball boy at a tennis court to buy a book about cave art. “Even though in a way I knew what was waiting for me because I had seen photos, I was in complete and overwhelming awe,” Herzog told The A.V. Club in 2011. “The mysterious origins of it—we don’t know why they were made, and why in complete darkness and not next to the entrance.”

13. You can visit a scale replica of the Chauvet Cave paintings.

The world-famous Paleolithic cave paintings at Lascaux, not far from Pont d’Arc, were damaged by the exhalations of thousands of visitors after the cave was opened to the public in 1948. So, immediately after Chauvet Cave was discovered, scientists moved to protect the fragile paintings and closed it to the public; now, only scholars are allowed in during brief windows of time. But that doesn’t mean you can’t see a simulation of the artwork up close. In 2015, a scale replica of the Chauvet Cave paintings, dubbed the Caverne du Pont d’Arc, opened near the site of the actual cave. Engineers and artists faithfully recreated not just the dazzling paintings, but also the temperature, dampness, murk, and funky smell of the original.

The Person Who Solves the Mysterious Inscription on This French Rock Will Be Awarded $2200

iStock.com/GAPS
iStock.com/GAPS

In the village of Plougastel-Daoulas in the Finistere region of Brittany, France, there's a boulder that's only uncovered at low tide. When waters recede, a mysterious inscription carved into one side becomes visible, and though it's written in the Latin alphabet, no one has been able to decipher the message. The only scrutable components are the years 1786 and 1787—suggesting the carving is at least 230 years old. Now, The Local France reports that the village is offering €2000 (roughly $2242) to anyone who can break the code.

According to the mayor of Plougastel-Daoulas, the cipher was discovered on the town's shore a few years ago. The letters, most of which are capitalized, look like they might spell clear words from far away, but upon closer inspection they seem to be arranged in no apparent order. Lines contain nonsense like "DRE AR GRIO SE EVELOH AR VIRIONES BAOAVEL," and "R I OBBIIE: BRISBVILAR." There are also pictures of objects like sailboats etched into the stone.

If the message was written in the late 18th century as the dates indicate, various artillery batteries would have been stationed on Brittany's coast, including at Corbeau Fort which is beside the site. Beyond that, town authorities have no clues as to the inscription's origins. Some people think it's written in Basque or old Breton, but the town wants to hear what a professional code-breaker has to say.

Plougastel-Daoulas is calling on linguists, historians, academics, students, and hobbyists to examine the carving and determine its meaning. When all the translations are submitted, a jury will convene to select the most likely possibility and award the code-breaker the €2000.

In some cases, even years worth of studying ciphers isn't enough to crack a code. A code found in the pocket of a murder victim stumped the FBI for more than a decade, and the centuries-old Voynich Manuscript is still undeciphered.

[h/t The Local France]

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