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.

A WWII Navy Submarine, Lost for 75 Years, Has Been Discovered Off the Coast of Japan

MR1805/iStock via Getty Images
MR1805/iStock via Getty Images

The U.S. Navy lost 52 submarines during World War II, many of which are still missing today. But as The New York Times reports, the wreck of the U.S.S. Grayback—a submarine that disappeared along with its 80-person crew in 1944—has been found off the coast of Okinawa, Japan.

On January 28, 1944, the Grayback departed from Pearl Harbor for its 10th combat patrol. It missed its scheduled return date that spring, and after weeks of failing to locate the vessel, the Navy declared it was likely lost.

Immediately following World War II, the U.S. military studied Japanese war records in search of clues that might lead them to their missing ships. One recording clearly states the Grayback was brought down by a bomb dropped by an Japanese aircraft, and it even gives the longitude and latitude of the attack. But due to a poor translation of the audio, the Navy went looking for the sub 100 miles away from its actual resting place.

Seventy-five years later, the submarine's coordinates were finally uncovered in old Imperial Japanese Navy files.

A Japanese researcher named Yutaka Iwasaki noticed this error while looking at the World War II records of the Imperial Japanese Navy base at Sasebo. He was asked to review the files for the Lost 52 Project, an organization dedicated to finding lost World War II submarines. Using the newly uncovered information and an autonomous underwater vehicle, the team was able to locate the vessel at the bottom of the East China Sea near Okinawa.

Lost 52 doesn't hunt for submarine wrecks with plans to recover them. Rather, the goal of the project is "documenting and preserving the story of the Lost 52 WWII Submarines, leaving a foundation of knowledge for future generations." In the case of the Grayback, the site where it settled on the seafloor will be protected from any human interference.

[h/t The New York Times]

Swedish Divers Just Discovered Two Shipwrecks That Might Be Related to the Famous Vasa Warship

The Vasa shipwreck displayed in Sweden's Vasa Museum.
The Vasa shipwreck displayed in Sweden's Vasa Museum.
Christian Lundh, Flickr // CC BY-NC 2.0

In 1625, King Gustavus II Adolphus of Sweden commissioned shipbuilders to create the most beautiful, lethal flagship that ever existed, as a symbol of Sweden’s naval strength. Three years later, crowds gathered to watch the Vasa, named after Sweden’s royal house, set sail for the first time. But less than a mile into its maiden voyage, the poorly and hastily constructed warship sunk to the bottom of the Baltic Sea, where it remained until 1961 when it was salvaged and later transported to the Vasa Museum.

Now, the Guardian reports Swedish maritime archaeologists from Vrak—Museum of Wrecks have located two shipwrecks in the Swedish archipelago outside of Vaxholm that could be linked to the Vasa. This is because the shipwright responsible for the Vasa built three other ships, the Äpplet, the Kronan, and the Scepter (though, unlike their ill-fated sibling, they actually made it into battle).

“It was like swimming around the Vasa ship,” maritime archaeologist Jim Hansson said in a museum press release. They believe the first wreck they discovered may be the Äpplet, and the second wreck could be either the Kronan or the Scepter.

“We think that some of them were sunk in the area,” Patrik Hoglund, another Vrak archaeologist, told the Guardian. But these ships didn’t capsize because of shoddy engineering or even an enemy attack. Instead, experts believe the Swedish navy intentionally sunk them after they were decommissioned, so their wrecks would function as surprise spike strips to damage approaching enemy ships.

The divers brought back wood samples from the wrecks to send to a laboratory for testing. Once they know when and where the timber came from, they can cross-reference the data with Swedish archives to find out if it matches information from the Vasa.

Even if the warships do turn out to be the Vasa’s long-lost siblings, it’s unlikely that they’ll be salvaged and displayed alongside it, since the Baltic Sea’s brackish waters actually preserve them much better than a museum could.

Sweden isn’t the only nation that boasts a beautiful shipwreck or two—here are 10 other shipwrecks around the world that you can visit.

[h/t The Guardian]

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