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.

Laser Scans Detect Hidden Buildings and Tunnels Beneath Alcatraz Prison

iStock.com/f8grapher
iStock.com/f8grapher

Isolated in the San Francisco Bay and surrounded by steep cliff faces, Alcatraz Federal Penitentiary seemed like the most secure place to keep dangerous criminals in the mid-20th century. But it's recently come to light that every inmate on Alcatraz Island lived above a series of potential escape routes that predated the prison's construction, the San Francisco Chronicle reports.

In a new study published in the journal Near Surface Geophysics, archaeologists reported their discovery of structures and artifacts beneath the Alcatraz prison yard, including underground buildings, tunnels, and ammunition magazines. Guided by historical maps, documents, and photographs, they used laser scanning technology and ground-penetrating radar to locate the subterranean fortress close to the surface.

The site dates back to the mid-19th century, when Alcatraz Island was used for military purposes. The same natural features that would later make Alcatraz an appealing prison also made it an ideal coastal fortification. Enough brick buildings were built there to house 200 soldiers and enough food was shipped in to feed them for four months.

But the fortification wasn't used for its original purpose for very long. It was transformed into the West Coast's official military prison during the Civil War, and in the 1930s, the government turned it into a federal prison. Instead of tearing down the forts and tunnels leftover from its military days, workers left them intact and built over them to save money. Archaeologists plan to investigate the underground structures further without disturbing the historic site.

Alcatraz Prison closed in 1963, so the underground tunnels no longer pose a security problem. Today the island is part of the U.S. National Park Service and is a popular tourist attraction.

[h/t San Fransisco Chronicle]

The Site Where Julius Caesar Was Assassinated Will Open to the Public in 2021

iStock.com/Largo di Torre Argentina
iStock.com/Largo di Torre Argentina

Besides being a sanctuary for stray cats, Largo di Torre Argentina in Rome is best known as the place where Julius Caesar was stabbed 22 times by assassins in 44 BCE. As the city's oldest open-air square, the spot is an important piece of Roman history, but it's fallen into disrepair. Now, Condé Nast Traveler reports that Largo di Torre Argentina will reopen to the public following a $1.1 million restoration project.

The site includes four ancient temples, a medieval brick tower, and the ruins of the senate house where Caesar was murdered. About 20 feet below street level, it was excavated under the rule of Benito Mussolini in the 1920s, and has remained largely closed to the public since. Today, Largo di Torre Argentina is overgrown and accessible only to the feral cats that live there.

On Monday, February 25, Rome mayor Virginia Raggi announced that Largo di Torre Argentina will reopen in the second half of 2021. To get the site ready for the public, the city will add restrooms, install lights, and build walkways that allow visitors to explore the area. Stone ruins, some of which are stacked into piles, will be secured, and artifacts currently sitting in storage will be moved to a museum. The one area the project will avoid is the corner where the cat sanctuary is located.

Rome, of course, is filled with ancient ruins—some that residents weren't even aware of until recently. In 2014, a 2000-year-old Roman road was unearthed during the construction of a McDonald's.

[h/t Condé Nast Traveler]

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