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

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.
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.”

15th-Century Cannonballs Likely Used by Vlad the Impaler Discovered in Bulgaria

By Anonymous, Public Domain, Wikimedia Commons
By Anonymous, Public Domain, Wikimedia Commons

Dracula was known for using his fangs and supernatural powers to dispatch his victims. But he apparently liked to have a few cannonballs by his side as well (just in case).

No, there’s no secret passage from Bram Stoker’s novel involving a battle where the vampire count displays his firepower. Rather, according to the website Archaeology in Bulgaria, cannonballs were recently excavated from the Bulgarian town of Svishtov, the site of a military conquest made by the Romanian prince Vlad III. Known more popularly as “Vlad the Impaler,” he likely served as the inspiration behind Stoker's bloodthirsty antagonist.

During his reign as one of most ruthless rulers in history, Vlad III frequently butted heads with the Ottoman Turks. The conflict came to a violent head in 1461, when Vlad and his army fought for control over Svishtov’s Zishtova Fortress. Now, as Gizmodo reports, archaeologists say they've uncovered a collection of centuries-old cannonballs that may have belonged to Vlad and were most likely linked to the event.

The cannonballs themselves were shot from culverins, medieval cannons that fired missiles weighing up to 16 pounds, which were relatively light compared to later models. Lead archaeologist Nikolay Ovcharov of the National Institute and Museum of Archaeology in Sofia said that's what makes these artifacts particularly exciting.

“We rejoice at those small cannonballs because they are from culverins," Ovcharov told Fox News. "These were the earliest cannons which were for the 15th century, up until the 16th century, [and] they weren’t in use after that.”

That battle occurred as an attempt to reclaim the region from the occupying Turks. The region was occupied as far back as the Roman Empire and was abandoned after barbarian invasions. The Zishtova Fortress was built much later, and Vlad III made it his home—after he reclaimed it from his enemies.

But just because Vlad may have had cannonballs at his disposal doesn't mean that some of the battle's victims weren't impaled.

"[We] have a letter by Vlad Dracula to the king of Hungary in which he boasted that he had taken [the fort] after a fierce battle, and that about 410 Turks were killed during the siege," Ovcharov said. "Some of them were probably impaled, in his style."

Easter Island Statues Are Being Threatened By Nose-Picking Selfie-Seekers

iStock/filipefrazao
iStock/filipefrazao

Though geographically tiny at just 64 square miles, Easter Island, or Rapa Nui, is home to a rich a history that's been attracting visitors for centuries. Now, one of the top experts on the island warns that inappropriate behavior from tourists could harm the ancient site, HuffPost reports.

Jo Anne Van Tilburg is an archaeologist who first visited Rapa Nui in the early 1980s. Her team has studied the Easter Island heads (known as moaiup close and uncovered the bodies buried beneath them, revealing that the full moai statues are actually up to 33 feet tall.

As Van Tilburg shared in a recent interview on 60 Minutes, a lot has changed since she first set foot on the island. In the early 1980s, Easter Island received about 2500 visitors a year; in 2018, 150,000 tourists flocked there to see the mysterious artifacts. That many annual visitors wouldn't be a lot for some destinations, but on Rapa Nui, an island with a permanent population of 5700 that relies on a generator for power and a limited water supply, those numbers can be devastating.

To make matters worse, many guests act in disrespectful ways when they arrive. According to Van Tilburg, it's not unusual to see tourists illegally climbing on top of the statues and pretending to pick their noses for selfies. "I am troubled by the lack of genuine tourist interest in the island and its people," Van Tillburg said. "There is a lack of genuine appreciation for the Rapa Nui past.”

The island's scarce resources and delicate ecosystem have long been a problem for the people who live there. This may have even led to the site's iconic statues: A recently published study posits that the moai were positioned in certain spots to mark precious sources of fresh water.

[h/t HuffPost]

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