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Two views of an adult Homo naledi cranium found in the Lesedi Chamber of the Rising Star cave system in South Africa, where the remains of 15 individuals were discovered in a different cave in 2013.
Hawks et al. in eLife, 2017

Puzzling Human Relative Homo Naledi May Have Lived at the Same Time as Our Ancestors

Original image
Two views of an adult Homo naledi cranium found in the Lesedi Chamber of the Rising Star cave system in South Africa, where the remains of 15 individuals were discovered in a different cave in 2013.
Hawks et al. in eLife, 2017

It's tempting to think that evolution works in a straight line, with clearly defined, graduated steps from primitive to modern. We humans are especially prone to telling our own evolutionary story in this manner. Evolution doesn't work that way, though, and we aren’t even the end point of human evolution, but works in progress. (Personally, I hope we are amphibious and have fins in 3 million years. That would be awesome.)

The latest evidence for that essential truth comes from the Rising Star cave system in South Africa, where scientists say Homo naledi, the unusual hominid species they discovered there in 2013, is surprisingly young, living as recently as 236,000 years ago. That means it was one of various hominids wandering the Earth at the same time as the Neanderthals in Europe; the Denisovans in western Asia; the ancestors of the “hobbit,” Homo floresiensis; and, in Africa, potentially alongside the earliest members of our own species, Homo sapiens.

Moreover, the researchers found three more individuals in another chamber in the cave system, one of them with the most complete H. naledi skull discovered yet. (You can see it above.) Today the large team of researchers published a trio of papers documenting their results in the open-access journal eLife.

In 2015, we reported on the initial discovery of 15 sets of hominid remains found in the Dinaledi cave by a team of researchers led by paleoanthropologist Lee Berger. It was an unprecedented bounty of bones. Often, paleoanthropologists are reconstructing human evolutionary history from scant remains—a fragment of skull or jaw bone here, a femur or a finger there. But in the Dinaledi cave, there are at least 1500 bones, and likely a lot more, since only a small fraction of the cave was excavated by a half-dozen archaeologists—all female, all cavers, all slim enough to squeeze through a series of cave tunnels that narrowed to just 7 inches in one spot—who worked in extraordinary conditions to excavate the bones from a pitch-black cave nearly 100 feet beneath the surface.

The ancient creatures were no bigger than the small but formidable women who unearthed them. Slender and about 5 feet tall as adults, they would’ve weighed just under 100 pounds. Their bodies are a fascinating mosaic of primitive and modern: tiny, orange-sized brains housed in skulls with jaws and teeth closer to early Homo; shoulders suited for climbing trees but feet and ankles made for walking; hands potentially capable of making tools, but with fingers well-curved for tightly gripping tree branches.

The discovery made headlines worldwide. Most of us—whether scientist or science nerd—fascinated by the find had one question: How old were they?

DATING THE REMAINS

When H. naledi was first discovered, the researchers deliberately didn’t attempt to answer that question. Determining where a species fits into the evolutionary record based on its morphology is not an unusual approach, but it can also be misleading. In the past 1.5 years, other scientists have proposed ages for H. naledi that range from 100,000 to 2 million years ago.

In one of the current studies, researchers led by James Cook University geologist Paul Dirks conducted six dating tests to narrow the age range, including the paleomagnetic dating of calcite left behind by running water and a chemical analysis of three fossil teeth discovered in the cave using a technique called combined U-series and electron spin resonance (US-ESR) dating. From all the tests, they came up with an age range: they're most likely between 236,000 and 335,000 years old.

As eLife notes in a commentary on the study, “The estimated dates are much more recent than many had predicted, and mean that H. naledi was alive at the same time as the earliest members of our own species—which most likely evolved between 300,000 and 200,000 years ago. These new findings demonstrate why it can be unwise to try to predict the age of a fossil based only on its appearance, and emphasize the importance of dating specimens via independent tests.”

American Museum of Natural History paleoanthropologist Ian Tattersall echoed that sentiment to Mental Floss. “This is an object lesson in trying to date anything by what it looks like,” he says. While he doesn't find the age estimate surprising, he’s less convinced that H. naledi belongs in our Homo genus: “Anything as odd as this is always going to be tough to fit into both a phylogeny and a timescale,” he notes.

Did our ancestors interact with this oddball? We have no idea. But we do know that the picture of human evolution continues to expand in detail and complexity with every discovery like H. naledi.

Bioarchaeologist (and regular Mental Floss contributor) Kristina Killgrove, who teaches biological anthropology, human origins, and evolutionary theory at the University of West Florida, tells us that the long wait for H. naledi dates was “worth it.”

She says, “These dates reveal a much more complicated story of hominin evolution than ever before. We used to think of human evolution as a single lineage—the classic image of the progression from apes to humans. But H. naledi shows that palaeoanthropologists are onto something far more complex—and far more interesting! While these new dates won't make it into textbooks in time for the fall semester, I will certainly be updating my human evolution lectures this summer."

ONE NEW CAVE, THREE NEW BODIES

Whatever we have to learn about this cousin of humanity can only be helped by the other discovery reported today in eLife: 133 bones from three likely H. naledi individuals—two adults and one child—found in another cave in the Rising Star system. First spotted in 2013 by cavers, the bones were unearthed in three locations in a cave the researchers coined Lesedi. The two caves are found at the same depth, but they’re not directly connected.

As with the first expedition into the Dinaledi cave, the working conditions for the researchers weren’t easy: Wits University archaeologist Marina Elliott, who led the intrepid team of “underground astronauts” who excavated both sites, told National Geographic that while the Lesedi cave was slightly easier to reach than Dinaledi, she still had to excavate one set of remains from a 2-foot-wide alcove while laying on her chest, her shoulders pinned between rocks. “It’s extremely physically difficult,” she said. “I’ve tried to do a lot of yoga to get myself to be able to do it.”

Elliott would probably say it was worth it, though; the remains she excavated in that location yielded the most complete H. naledi skull so far discovered. Dubbed Neo (after the Setswana word for "a gift," not the The Matrix character), this adult has a larger skull—and therefore a larger brain capacity—than the other specimens so far discovered, but it falls within an expected range.

ARE THESE BURIALS OF A SORT?

One of the most contentious theories Berger and the team proposed when the first H. naledi fossils were discovered was that these bodies had been intentionally placed in the cave in some sort of death ritual. Berger and John Hawks, a paleoanthropologist at the University of Wisconsin, revisit that theory in the third paper published in eLife. They point out that the caves are difficult to access and aren’t obvious “death traps” that individuals could’ve accidentally fallen into. Nor did the remains show any signs of mass death, having been fed upon by carnivores or scavengers, or of having been flushed into the caves by a water system.

So how did they get there?

The researchers write, “We propose that funerary caching by H. naledi is a reasonable explanation for the presence of remains in the Dinaledi and Lesedi Chambers. Mortuary behaviors, while culturally diverse, are universal among modern human cultural groups. Such behaviors are not seen in living non-human primates or in other social mammals, but many social mammals exhibit signs of grief, distress, or other emotional response when other individuals within their social group die.”

They say that while there’s no evidence of symbolic thinking among H. naledi, such sophisticated thought isn’t necessarily a requirement for a death ritual. The “physical and social effects of the deaths of group members” could have been motivation enough.

“Such behavior may have many different motivations, from the removal of decaying bodies from habitation areas, to the prevention of scavenger activity, to social bonding, which are not mutually exclusive,” they note. “We suggest only that such cultural behavior may have been within the capabilities of a species that otherwise presents every appearance of technical and subsistence strategies that were common across the genus Homo.”

Original image
Two views of an adult Homo naledi cranium found in the Lesedi Chamber of the Rising Star cave system in South Africa, where the remains of 15 individuals were discovered in a different cave in 2013.
EEF, Black Sea MAP
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Stones, Bones, and Wrecks
'Ship Graveyard' Discovered in the Black Sea Provides New Insights into Maritime History
Original image
Rendering of a Roman ship hull by Black Sea MAP researchers.
EEF, Black Sea MAP

In 2015, to learn how prehistoric humans dealt with the coastal impact of climate change, an international team of researchers in Bulgaria embarked on a multiyear geophysical survey of the Black Sea. Little did they know that the undertaking would morph into what's been dubbed "one of the largest maritime archaeological projects ever staged": As IFLScience reports, the team ended up discovering dozen of shipwrecks, dating from the 19th century all the way back to the 5th century BCE.

News of the "ship graveyard," as researchers have taken to calling it, was first announced in 2016. Following three field seasons, marine scientists have just returned from their final trip with recovered artifacts and new insights about ancient ship design and trade patterns.

Scientists from the Black Sea Maritime Project (Black Sea MAP), conducted by the University of Southampton's Center for Maritime Archaeology, used a host of high-tech equipment to survey the Black Sea's floor and take pictures. In all, they located around 60 ships spanning 2500 years of history.

The vessels were in remarkable condition, considering their age. The Black Sea is uniquely suited for preserving organic materials, as it contains two separate layers of water: a top layer that contains oxygen and salt, and a second salty layer with little oxygen or light. Organisms that eat organic matter can't survive in this environment, which is why the site's ships stayed relatively intact.

According to National Geographic, researchers were still able to make out the chisel and tool marks on planks, along with carved decorations. They also saw rigging materials, rope coils, tills, rudders, standing masts, and cargo.

Ships were discovered from the Classical, Roman, Byzantine, and Ottoman periods, with the oldest dating back to the 4th or 5th century BCE. One particularly exciting find was an ornately carved Ottoman ship, which researchers nicknamed Flower of the Black Sea due to its floral deck carvings. Meanwhile, a potentially Venetian ship from the 13th or 14th century provided scientists with a first-ever glimpse of the ships that were the precursors to those used during the Age of Exploration.

"That's never been seen archaeologically," expedition member Rodrigo Pacheco-Ruiz told The New York Times in 2016. "We couldn't believe our eyes."

To reconstruct how these vessels once looked, researchers used 3D software to combine thousands of still photos shot from different angles. This photogrammetric method allowed them to create digital models of the vessels and identify historical features that were once a mystery to archaeologists.

"There's one medieval trading vessel where the towers on the bow and stern are pretty much still there," said Ed Parker, CEO of Black Sea MAP, according to IFLScience. "It's as if you are looking at a ship in a movie, with ropes still on the deck and carvings in the wood."

A 3D recreation of a Roman galley discovered by an international team of researchers in the Black Sea.
A 3D rendering of a Roman galley, created by Black Sea MAP project researchers.
EEF, Black Sea MAP

Photogrammetric model of a wreck from the Medieval period, created by Black Sea MAP researchers.
Photogrammetric model of a wreck from the Medieval period, created by Black Sea MAP researchers.
EEF, Black Sea MAP

Photogrammetric model of the stern of an Ottoman wreck, created by Black Sea MAP researchers.
Photogrammetric model of the stern of an Ottoman wreck, created by Black Sea MAP researchers.
EEF, Black Sea Map

A Roman shipwreck discovered by an international team of researchers in the Black Sea.
Divers with the Black Sea MAP project examining the Roman galley.
EEF, Black Sea MAP

Scientists say the ship graveyard will help them learn more about ancient trade routes, and how various Black Sea coastal communities were connected. That said, they're still committed to their initial goal of investigating ancient changes in the region's environment, using sedimentary core samples and other methods to learn more about the impact of sea level change after the last glacial cycle.

"Our primary aims are focused on the later prehistory of the region and in particular on human response to major environmental change," said Jon Adams, the project's chief investigator and a founding director of the University of Southampton's Centre for Maritime Archaeology, in a news statement. "We believe we now have an unparalleled archive of data with which to address these big questions about the human past."

[h/t IFLScience]

Original image
Two views of an adult Homo naledi cranium found in the Lesedi Chamber of the Rising Star cave system in South Africa, where the remains of 15 individuals were discovered in a different cave in 2013.
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Stones, Bones, and Wrecks
Found: A Sunken German World War I-Era Submarine
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SMU Central University Libraries, Flickr/Public Domain

During World War I, one of Germany's most formidable weapons was the U-boat, an advanced military submarine with torpedoes that sank countless Allied merchant and cargo ships. But while deadly, these submersibles weren't invincible, as evidenced by the recent discovery of a sunken German U-boat in the North Sea.

As ABC News reports, researchers located the UB II-type dive boat—a smaller submarine that typically plagued coastal waters—off the coast of Belgium, around 82 to 98 feet below the North Sea. The 88-foot vessel appears to have struck a mine with its upper deck, judging by damage suffered to its front.

The submarine is remarkably intact. Two of its torpedo tubes were destroyed, but one of them is still in good condition. The ship itself remained sealed, and may serve as a watery grave for up to 23 crew members.

The U-boat's final resting place hasn't been announced, as to prevent looting or damage, according to the BBC. Meanwhile, Belgian officials have contacted the German ambassador to see how they should proceed with any potential remains.

This isn't the first time a World War I-era U-boat has been found in Belgian waters. Experts have catalogued 11 such discoveries so far, but this one is reported to be the best preserved. The Chicago Tribune reports that since 18 U-boats were stationed in Bruges between 1915 and 1918, and 13 of them were destroyed, there might be even more of these kinds of finds to come.

[h/t ABC News]

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