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.”

Looking to Downsize? You Can Buy a 5-Room DIY Cabin on Amazon for Less Than $33,000

Five rooms of one's own.
Five rooms of one's own.
Allwood/Amazon

If you’ve already mastered DIY houses for birds and dogs, maybe it’s time you built one for yourself.

As Simplemost reports, there are a number of house kits that you can order on Amazon, and the Allwood Avalon Cabin Kit is one of the quaintest—and, at $32,990, most affordable—options. The 540-square-foot structure has enough space for a kitchen, a bathroom, a bedroom, and a sitting room—and there’s an additional 218-square-foot loft with the potential to be the coziest reading nook of all time.

You can opt for three larger rooms if you're willing to skip the kitchen and bathroom.Allwood/Amazon

The construction process might not be a great idea for someone who’s never picked up a hammer, but you don’t need an architectural degree to tackle it. Step-by-step instructions and all materials are included, so it’s a little like a high-level IKEA project. According to the Amazon listing, it takes two adults about a week to complete. Since the Nordic wood walls are reinforced with steel rods, the house can withstand winds up to 120 mph, and you can pay an extra $1000 to upgrade from double-glass windows and doors to triple-glass for added fortification.

Sadly, the cool ceiling lamp is not included.Allwood/Amazon

Though everything you need for the shell of the house comes in the kit, you will need to purchase whatever goes inside it: toilet, shower, sink, stove, insulation, and all other furnishings. You can also customize the blueprint to fit your own plans for the space; maybe, for example, you’re going to use the house as a small event venue, and you’d rather have two or three large, airy rooms and no kitchen or bedroom.

Intrigued? Find out more here.

[h/t Simplemost]

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Humans First Arrived in North America 30,000 Years Ago, New Studies Suggest

Researcher samples cave sediments for DNA.
Researcher samples cave sediments for DNA.
Devlin A. Gandy

People occupied North America by roughly 11,000 BCE, but the exact timeline of how early humans first arrived on the continent is contested. Two new studies suggest that humans were living in North America as far back as 30,000 years ago—preceding some earlier estimates by more than 15,000 years.

According to the traditional narrative, the first North Americans were big game hunters who crossed a land bridge connecting Asia to North America around 13,000 years ago. They left behind distinct, fluted arrowheads and bone and ivory tools that were dubbed “Clovis” tools. “This narrative, known as ‘Clovis-first,’ was widely accepted for most of the 20th century until new archaeological evidence showed that humans were present in the continent before Clovis,” Lorena Becerra-Valdivia, an archaeological scientist with the Universities of Oxford and New South Wales and co-author of the new studies, tells Mental Floss. “Within academia, an earlier arrival of 16,000-15,000 years ago was generally accepted.”

Her new analysis pushes back that date by several millennia. The study, “The Timing and Effect of the Earliest Human Arrivals in North America,” published in the journal Nature, looks at radiocarbon and luminescence data from Beringia, a region that historically linked Russia and Alaska, and North America. A statistical model built with this data indicates that a significant human population was living on the continent long before the Clovis era. According to the study, these humans were likely present before, during, and after the Last Glacial Maximum—the period when ice sheets covered much of North America 26,000 to 19,000 years ago.

Stone tool found below the Last Glacial Maximum layer.Ciprian Ardelean

These findings also contradict the land bridge theory. Rather than making a straightforward journey from Asia to North America and populating the southern half of the continent as the Clovis people were thought to have done, the first humans may have entered the Americas by traveling down the Pacific Coast. “These are paradigm-shifting results that shape our understanding of the initial dispersal of modern humans into Americas,” Becerra-Valdivia says. “They suggest exciting and interesting possibilities for what likely was a complex and dynamic process.”

The second, related study in Nature, ”Evidence of Human Occupation in Mexico Around the Last Glacial Maximum,” supports this new narrative. In it, researchers from institutes in Mexico, the UK, and other countries share artifacts and environmental DNA uncovered from Chiquihuite Cave—a high-altitude cave in Zacatecas, central Mexico. The tools, plant remains, and environmental DNA collected there paint of picture of human life dating back 13,000 to 30,000 years ago. The evidence shows that the site was more than just a stopping point, and the people living there had adapted to the high altitudes and harsh mountain landscape.

The two studies not only offer insight on when the first North Americans arrived on the continent, but who they were and how they lived. The Americas would have looked a lot different to humans during the Last Glacial Maximum than they did to the Clovis people millennia later. The fact that the first North Americans left behind far fewer artifacts than the Clovis people shows that their populations stayed relatively small. “Humans at Chiquihuite Cave would have faced the harshness of the Last Glacial Maximum, the peak of the last Ice Age, which would have kept their population at a low density,” Becerra-Valdivia says. “Clovis peoples, in contrast, thrived well after the last Ice Age, expanding widely through the continent during a period of globally warmer temperatures. Their life ways and subsistence patterns, therefore, would have been very different.”