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.”

Advanced CT Scans Reveal Blood Vessels and Skin Layers in a Mummy's Hand

Jenny Romell, et al./Radiology
Jenny Romell, et al./Radiology

Mummies hold some intriguing secrets to their pasts, like the food they ate and the diseases they had when they were alive. Now scientists are using a tool originally designed for medicine to get an even deeper look at the clues mummified bodies carry with them into the present day, Gizmodo reports.

In a proof-of-concept study published in the journal Radiology, researchers from the KTH Royal Institute of Technology in Sweden detail how a new-and-improved CT scanning technique can be used to visualize the interior of mummies on a microscopic level. By creating detailed X-ray images, CT scans allow doctors to see inside their patients without invasive surgery. Archaeologists have been using this technology to study delicate ancient artifacts for years, but the level of detail that can be achieved this way—especially when it comes to looking at interior soft tissue—is limited.

The upgraded version of the tech, called phase-contrast CT scanning, measures the phase shift, or the change in the position of a light wave, that occurs when X-rays pass through solid objects. The images generated this way have a higher contrast level than conventional X-rays, which means they capture more detail.

Cross-section of mummy hand.
Jenny Romell, et al./Radiology

Doctors have been using this 10-year-old technology to examine soft tissues like organs and veins in living patients, but it hadn't been used on a mummy until recently. Working with a mummified human right hand dating back to 400 BCE in Egypt, which they borrowed from the Museum of Mediterranean and Near Eastern Antiquities in Stockholm, the researchers fired up a phase-contrast CT scanner. It produced images with a resolution of 6 to 9 microns, giving a clear picture of the different layers of skin, individual cells in the connective tissue, and the blood vessels in the nail bed—all without damaging the artifact. Previously, researchers looking to study these same tissues in mummies would have needed to use a scalpel.

As Ars Technica reports, a phase-contrast CT scanner is similar in cost to the conventional machine. The study authors hope their work will lead to phase-contrast CT scanning becoming just as common in archaeology as regular CT scanning, potentially creating new research opportunities in mummies that will be discovered in the future and even in artifacts that have already been examined.

[h/t Gizmodo]

A 2.63-Carat Diamond Was Unearthed by a Grandmother at an Arkansas State Park

iStock
iStock

Visitors to the Crater of Diamonds Park in Murfreesboro, Arkansas clearly have an objective in mind: Excavate one of the diamonds lurking on or beneath the park's soil, the onetime site of a volcanic crater. If they do, it's theirs to keep.

Earlier this month, a 71-year-old grandmother from Colorado made the biggest discovery on park grounds of 2018: a 2.63-carat ice white diamond. And she did it in about 10 minutes.

The retiree, who asked media outlets not to identify her by name, visited Crater of Diamonds with her husband, son, and grandchildren. After briefly scraping away dirt, she saw the gem on the surface. The diamond was so large and clear—roughly the size of a pinto bean—that she assumed it was just a piece of glass. Further inspection by her family and park personnel revealed it was a diamond.

Park officials told press that employees frequently till the soil, which can loosen the gems and allow them to catch the reflection of the sun, making them easier to spot. Roughly 33,000 diamonds have been found by visitors since the park opened in 1972.

It's hard to know the exact value of the diamond. While there is a certain fluctuating value assigned to a carat, appraisers also look at three other "Cs": clarity, color, and cut. A two-carat diamond is often more than double the price of a one-carat diamond because the larger gems are more rare. But tourists have profited from their finds: In 2015, a visitor retrieved a 8.51-carat white diamond that was cut down to 4.6 carats by a jeweler and valued by the American Gem Society at $500,000.

[h/t WGN TV]

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