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A Neanderthal skull
A Neanderthal skull
Stephane De Sakutin, AFP/Getty Images

Scientists May Have Finally Figured Out Why We Have Eyebrows

A Neanderthal skull
A Neanderthal skull
Stephane De Sakutin, AFP/Getty Images

If you look at a pictures of some of the earlier branches of humanity's family tree, like Neanderthals or Homo erectus, you might notice that Homo sapiens got off relatively lightly, eyebrow-wise. Most early hominins had thick, bony brow ridges rather than the smooth brows of modern humans. For years, researchers have been arguing over why those thick ridges existed—and why modern humans evolved tinier brows. A new study suggests that heavy brow ridges had social usefulness that was more important than their physiological function.

Previous research has suggested that thick brow ridges helped connect early hominins' eye sockets with their brain cavities, or protected the skull from the physical stress put on it by chewing jaws, or even helped early hominins take punches to the face.

The new study by University of York researchers, published in the journal Nature Ecology & Evolution, used a digital model of a fossil skull, thought to be between 125,000 and 300,000 years old, of an extinct species called Homo heidelbergensis that evolved sometime between 300,000 and 600,000 years ago in what is now Zambia. The researchers manipulated the model, changing the size of the brow ridge and seeing what happened when they applied different bite pressures. They found that the brow ridge was much bigger than it needed to be if its purpose was just to connect the eye sockets with the brain case, and that it didn't seem to protect the skull from the force of biting.

Instead, the researchers suggest that the brow ridge played a social role. Other primates have similar brow ridges that serve a social purpose rather than a mechanical one, like male mandrills, whose colorful, heavy-browed muzzles serve as dominance displays. Heavy brow ridges may have played a similar role in early human species.

As Homo sapiens evolved, more subtle communication may have taken precedence over the permanent social signal of a giant brow ridge. As foreheads became more vertical, eyebrows could move more freely and subtly, leading to important social signals in modern humans, like expressions of surprise or indignation.

An accompanying analysis in the same journal, by Spanish paleontologist Markus Bastir, cautions that the results of the new study are appealing, but should be taken with a grain of salt. The specimen used for the digital model was missing a mandible, and the researchers subbed in a mandible from a Neanderthal, a related species but still a distinct one from Homo heidelbergensis. This may have altered the analysis of the model and bite stresses. Still, the study provides "exciting prospects for future research," he writes.

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A Neanderthal skull
Stefan Sauer, AFP/Getty Images
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Stones, Bones, and Wrecks
13-Year-Old Amateur Archaeologist Discovers the Buried Treasure of a Danish King
Stefan Sauer, AFP/Getty Images
Stefan Sauer, AFP/Getty Images

In January, amateur archaeologist René Schön and his 13-year-old student Luca Malaschnitschenko were scouring a field on an island in the Baltic Sea when something small and silver triggered their metal detector. What they initially thought was aluminum trash turned out to be a coin from a 10th-century treasure hoard that once belonged to a Danish king, AP reports.

Schön and Malaschnitschenko discovered the site on the eastern German island of Ruegen, but it wasn't until mid-April that state archaeologists uncovered the hoard in its entirety. Both of the amateur archaeologists were invited back to take part in the final dig, which spanned 4300 square feet.

The treasure trove includes pearls, jewelry, a Thor's hammer, and about 100 silver coins, with the oldest dating back to 714 CE and the most recent to 983 CE. Experts believe the collection once belonged to the Viking-born Danish king Harald "Harry" Bluetooth, who abandoned his Norse faith and brought Christianity to Denmark.

Pile of silver coins.
Stefan Sauer, AFP/Getty Images

Threatened by a rebellion led by his son, the king fled Denmark in the late 980s—around the same time the silver hoard was buried—and took refuge in Pomerania, on the southern coast of the Baltic Sea. He died there in 987.

Harry Bluetooth derived his nickname from his bluish dead tooth. Today his legacy lives on in the Swedish Bluetooth technology that bears his name. The symbol for the tech also uses the runic characters for his initials: HB.

According to the archaeologists who worked there, the dig site represents the largest trove of Bluetooth coins ever discovered in the southern Baltic region.

[h/t AP]

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A Neanderthal skull
Aaron Deter-Wolf and the Tennessee Division of Archaeology
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Stones, Bones, and Wrecks
This May Be the Oldest Tattoo Kit in the World
Aaron Deter-Wolf and the Tennessee Division of Archaeology
Aaron Deter-Wolf and the Tennessee Division of Archaeology

Tattooing is an ancient art, but it has left only ephemeral traces in the archaeological record. Examples of mummies with ink-decorated skin do exist—such as Ötzi the Iceman and the Siberian Ice Maiden—but they're rare. And archaeologists are only just beginning to distinguish tattoo needles from other tools that were used for tasks like working leather or weaving baskets.

Despite those challenges, a pair of researchers thinks they've identified what could be the world's oldest tattooing toolkit: a set of pointy, ink-stained needles that were carved out of wild turkey bones and then buried in a Native American grave at least 3600 years ago.

The burial was found west of Nashville, Tennessee, at a riverside campsite called the Fernvale site, which had been used by prehistoric hunter-gatherers for centuries. The settlement was excavated to make way for a bridge in 1985, but archaeologists at the time did not fully analyze the findings. The set of bone needles, pigment-filled half-shells, and stone tools were collectively labeled a toolkit and put into storage, where they spent the next three decades.

"It was one of these situations where it went into a collection and nothing was done with it," says Aaron Deter-Wolf, an archaeologist with the Tennessee Division of Archaeology and an expert in ancient tattoos.

3600 year old tattoo needles
Aaron Deter-Wolf

Deter-Wolf teamed up with Tanya Peres, a zooarchaeologist at Florida State University, to take a fresh look at the set of artifacts. They were initially interested in the toolkit because it resembled a medicine bundle—a collection of artifacts that was bound together to act like a portable shrine in more recent Native American cultures. But after examining the objects, the researchers thought they might be dealing with a tattoo kit.

"By the arrival of the Europeans, virtually every Native American group in the Great Plains and the Eastern Woodlands practiced tattooing," Deter-Wolf tells Mental Floss. "If it's something that widespread and that important, we suspect that it is very deeply rooted in Native American history."

Their theory got a boost from another study published last year, in which Christian Gates St-Pierre, an archaeologist at the University of Montreal, tattooed pig skin with bone tools to test the wear-and-tear patterns that prehistoric tattoo needles should exhibit. He found that when it was used for tattooing, a bone needle would develop a bright polish—but only on the first 3 millimeters of the tip.

Deter-Wolf recently took those experiments one step further. He re-created one of Ötzi's tattoos on his own skin, using a bone tool and black ink to make 1500 individual punctures on his left wrist—and a permanent tattoo. 

attooing human skin using bone tools for an experimental archaeological evaluation
Aaron Deter-Wolf

Deter-Wolf and Peres said that two of the needles in the kit had the same wear-and-tear signatures that Gates found in his experiments. "At this point there's not another activity that we know of that would create that same pattern on bone tools," Deter-Wolf says.

They also found traces of red and black pigment on the tips of the tools. (They're awaiting the final results of an analysis to figure out the chemical makeup of this paint.) They presented their preliminary findings this week at the annual meeting of the Society for American Archaeology in Washington, D.C.

The toolkit is thought to be at least 3600 years old and could be even more ancient: Initial results from a radiocarbon study of shells found at the same site suggest an age of 5200 years. Either way, the tools predate a group of 3000-year-old tattooing tools made from volcanic glass that were identified in 2016 at an archaeological site on an island in the South Pacific.

King of Yamacraw and his nephew, mezzotint by John Faber the Younger
1739 messotint by John Faber the Younger of Tomo Chachi Mico, king of the Yamacraw, and his nephew Tooanahowi
© Yale University Art Gallery

While scholars know a lot about more recent Native American tattooing practices because of historical accounts and ethnographic studies after European contact, prehistoric tattooing remains more mysterious. For now it's impossible to know what kind of tattoos the Fernvale tools would have been used to create, or what meaning tattooing had for the people who lived along this Tennessee river valley during this era, called the Archaic period in North America.

"I think there has to be a whole lot more work done on Archaic lifeways in general before we can even start to parse the deeper meaning of tattooing in this period," Peres says. "We're still arguing about what they were eating and what kind of houses they living in, which are more durable things in the archaeological record."

Deter-Wolf expects archaeologists will identify more tattoo kits hiding in collections: "What I suspect is that once we start looking at more of these things, we're going to find that tattooing is an incredibly widespread activity."

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