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.

Fossilized Fat Shows 550-Million-Year-Old Sea Creature May Have Been the World's First Animal

Ilya Bobrovskiy, the Australian National University
Ilya Bobrovskiy, the Australian National University

A bizarre sea creature whose fossils look like a cross between a leaf and a fingerprint may be Earth's oldest known animal, dating back 558 million years.

As New Scientist reports, researchers from the Australian National University (ANU) made a fortunate find in a remote region of Russia: a Dickinsonia fossil with fat molecules still attached. These odd, oval-shaped creatures were soft-bodied, had rib structures running down their sides, and grew about 4.5 feet long. They were as “strange as life on another planet,” researchers wrote in the abstract of a new paper published in the journal Science.

Another variety of fossil
Ilya Bobrovskiy, the Australian National University

Although Dickinsonia fossils were first discovered in South Australia in 1946, researchers lacked the organic matter needed to classify this creature. "Scientists have been fighting for more than 75 years over what Dickinsonia and other bizarre fossils of the Edicaran biota were: giant single-celled amoeba, lichen, failed experiments of evolution, or the earliest animals on Earth,” senior author Jochen Brocks, an associate professor at ANU, said in a statement.

With the discovery of cholesterol molecules—which are found in almost all animals, but not in other organisms like bacteria and amoebas—scientists can say that Dickinsonia were animals. The creatures swam the seas during the Ediacaran Period, 635 million to 542 million years ago. More complex organisms like mollusks, worms, and sponges didn’t emerge until 20 million years later.

The fossil with fat molecules was found on cliffs near the White Sea in an area of northwest Russia that was so remote that researchers had to take a helicopter to get there. Collecting the samples was a death-defying feat, too.

“I had to hang over the edge of a cliff on ropes and dig out huge blocks of sandstone, throw them down, wash the sandstone, and repeat this process until I found the fossils I was after,” lead author Ilya Bobrovskiy of ANU said. Considering that this find could change our understanding of Earth’s earliest life forms, it seems the risk was worth it.

[h/t New Scientist]

Endeavour, Captain Cook's Lost Ship, Might Have Been Found—Solving a Centuries-Old Mystery

Wellcome Images, Wikimedia Commons // CC BY-SA 4.0
Wellcome Images, Wikimedia Commons // CC BY-SA 4.0

The exact location of the final resting place of Captain James Cook’s HMS Endeavour, which was sunk off the coast of Rhode Island 200 years ago, is considered one of maritime history’s greatest mysteries. Now, after a 25-year effort to pinpoint its remains among 13 sunken vessels, The Age reports that the Endeavour might have finally been identified.

British explorer James Cook left England on the Endeavour in 1768 headed for the South Pacific. He and his crew became the first European expedition to map the entire coast of New Zealand, and later, the first to reach Australia’s east coast. Along the way, they collected hundreds of previously unknown plant species, became the first Europeans to record a kangaroo sighting, and gathered evidence that would help disprove the existence of the long-speculated southern continent, Terra Australis, that hypothetically extended all the way up to the equator.

A replica of the 18th-century 'Endeavour' in the ocean
A replica of the Endeavour in 2004
Dennis4trigger, Wikimedia Commons // CC BY-SA 3.0

After that three-year journey, Cook and his crew returned to England. Though Cook became a legend, the Endeavour didn’t receive the star treatment. The British Royal Navy used it to ferry supplies to and from the Falkland Islands for several years before selling it to a private buyer. The ship was renamed the Lord Sandwich, and was eventually put into service transporting German mercenaries to fight on Britain's side in the American Revolution.

That’s how the ship ended up in Rhode Island, where it was stationed as part of the Royal Navy’s fleet in Newport Harbor and used as a prison ship for captured American soldiers. When French reinforcements came to assist American revolutionaries in Rhode Island, the British decided to sink their ships rather than allow them to be captured, creating a blockade out of scuttled vessels to block the French from getting into the harbor. They sank 12 transport vessels and set another on fire. Over the ensuing years, locals and French forces took equipment from the wrecks, but it’s never been entirely clear what happened to the remains.

The Rhode Island Marine Archaeology Project began to try to map and identify those remains starting in the early 1990s, and eventually figured out that the Lord Sandwich was the same ship as the HMS Endeavour. As the ship played a vital role in Australian history, the Australian National Maritime Museum then got involved with the project.

The two organizations have announced that they have lowered the number of potential wrecks that could be the Endeavour from 14 to five—and perhaps down to just one—by inspecting the area and measuring the wrecks against historic information about Cook's vessel. The researchers think the final resting place of the ship is located off the coast of Goat Island in Narragansett Bay, but to be absolutely certain, they’ll have to excavate the remains of the ship and examine its timbers. The researchers hope to have that work done by the 250th anniversary of Cook’s arrival in Australia’s Botany Bay—and his claiming of Australia as British territory—in 2020.

And there may be a battle over the remains. While the ship is considered a vital artifact of Australian history, the state of Rhode Island claimed ownership of all of the sunken ships in 1999, and they are overseen by the Rhode Island Historical Preservation and Heritage Commission.

[h/t The Age]

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