Did ancient humans eat a Paleo diet?

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Cave paintings from the Lascaux complex in France to Ubirr in Australia have one characteristic in common—they depict hunters and their prey. Very few of our Paleolithic ancestors seemed interested in doing still-life paintings of fruit and veg. Which is a shame, given that they would almost certainly have eaten a more balanced diet than we often give them credit for, says Cristiani.

“We have had a huge problem talking about the ancient human ,” notes Cristiani, an archaeologist based at the Diet and Ancient Technology Laboratory (DANTE) in Italy. “One reason for this is that decays. So when we come across early prehistoric sites, all we tend to find is preserved bones, and perhaps butchering tools.”

This is one reason why prehistoric archaeologists have tended to focus their resources on looking for such clues. This in turn has fed into the popular idea that prehistoric diets consisted primarily of animal proteins.

Our dietary evolution

The story of what ancient humans actually ate, and how our diet evolved, is far richer. This began around 2.5 million years ago, when Homo habilis would have started to use stone tools. Our earliest ancestors were most probably vegetarian, before meat was introduced to their diets through scavenging. With the invention of and the growth of social cooperation, we would then have learned to hunt for ourselves.

“The controlled use of fire was a great invention that allowed us to cook,” continues Cristiani. “The energy we previously would have needed to digest raw meat, and even raw vegetables, could then fuel our brain.”

A picture of ever increasing dietary complexity follows, with more advanced tools and the use of fire enabling us to outcompete other species. This dietary complexity—based on a mix of vegetation, grains and meat—would also have enabled us to prosper in vastly different climates.

“This is what really differentiated us from other primates,” says Cristiani. “While other species were stuck in an , we could migrate across the world using our tools and our brains, because of our diverse diets.”

Proof of a balanced diet

Still, there has to date been a dearth of concrete proof that ancient humans ate a balanced diet. To address this, Cristiani developed a way of identifying from food, which can remain trapped in hardened (called ) for millennia.

The HIDDEN FOODS project, of which Cristiani was coordinator, also recovered microscopic traces of starch from tools that might have been used to process tubers and grains. The project focused on remains from 40,000 to 8,000 years old, from a number of sites in Europe.

“We found that ancient societies who were thought to rely on fish or meat also ate wild cereals,” adds Cristiani. “Their diets were much more balanced. From the way that starches were preserved on their teeth and tools, we could also tell that they liked to make a sort of porridge.”

The technique was also able to show other behaviors such as the use of the mouth to tan hides, as well as the use of plants that are known for their medicinal properties. “This dental calculus is really a treasure from the past that we are scraping off,” remarks Cristiani.



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Astronomers confirm size of largest comet ever discovered, bigger than Rhode Island

Diagram comparing the size of the icy, solid nucleus of comet C/2014 UN271 (Bernardinelli-Bernstein) to several other comets. Credit: NASA, ESA, Zena Levy (STScI)

Astronomers using NASA’s Hubble Telescope have confirmed the existence the largest comet ever discovered, and it will pass by our sun in the next decade.

Comets are different from asteroids in that asteroids are rocky objects, while as a is a ball of ice and dust. Comets are also known for the “tail” they leave behind and the glowing head, or , that appears as it approaches the sun.

Now astronomers have determined the size of “the largest icy comet nucleus ever seen.” Comet C/2014 UN271, also known as Comet Bernardinelli-Bernstein, is about 80 miles wide, larger than Rhode Island. Its nucleus is estimated to weigh 500 trillion tons, about 100,000 times greater than most comets.

Also, the comet is traveling at 22,000 mph and headed closer to Earth. It won’t be of any concern when it makes its in 2031, because it will be around 1 billion miles away from the sun, slightly farther than the distance between Earth and Saturn. The findings on the comet were published Tuesday in the journal The Astrophysical Journal Letters.

“This comet is literally the tip of the iceberg for many thousands of comets that are too faint to see in the more distant parts of the solar system,” David Jewitt, and astronomy professor at UCLA and co-author of the study, said in a statement. “We’ve always suspected this comet had to be big because it is so bright at such a large distance. Now we confirm it is.”

First discovered by astronomers Pedro Bernardinelli and Gary Bernstein in archival images in 2014, the comet was spotted when it was more than 3 billion miles from the sun, an indicator of its size.

“We guessed the comet might be pretty big, but we needed the best data to confirm this,” said Man-To Hui of the Macau University of Science and Technology in Taipa, Macau, and lead author of the study.

To confirm the comet’s size, astronomers took images of it using the Hubble telescope on Jan. 8. But the challenge of deciphering the images was distinguishing the comet’s nucleus from the cloud and tail, or coma, surrounding it. As a comet gets closer to the sun, it heats up, and the coma expands.

The comet is around 2 billion miles away from the sun, where temperatures are an estimated minus 348 degrees Fahrenheit, but enough for the to sublimate off the comet’s surface to form the coma.

Hui and colleagues then made a computer model of the comet and adjusted it to the telescope images. They then were able to take out the coma to leave just the nucleus.

Hui and his colleagues next made a computer model of the surrounding coma and adjusted it to fit the Hubble images. Then they subtracted the glow of the .

The team then took the nucleus photos and compared its brightness to radio observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The combined data allowed to determine its diameter, as well as what the nucleus actually looks like.

“It’s big, and it’s blacker than coal,” Jewitt said.

The comet takes 3 million years to orbit the solar system, and it reaches as far as half a light-year from the sun.

Astronomers hope the comet will provide answers on what comets from the Oort Cloud are like. The Oort Cloud is believed to be a massive nesting ground for trillions of comets; it has yet to be observed directly.



More information:
Man-To Hui et al, Hubble Space Telescope Detection of the Nucleus of Comet C/2014 UN271 (Bernardinelli–Bernstein), The Astrophysical Journal Letters (2022). DOI: 10.3847/2041-8213/ac626a

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Hexbyte Glen Cove Life on Mars search could be misled by false fossils, study says

Hexbyte Glen Cove

Composite image showing some of the types of fossil-like specimens created by chemical reactions that could be found on Mars. Credit: Sean McMahon, Julie Cosmidis and Joti Rouillard

Mars explorers searching for signs of ancient life could be fooled by fossil-like specimens created by chemical processes, research suggests.

Rocks on Mars may contain numerous types of non-biological deposits that look similar to the kinds of fossils likely to be found if the planet ever supported life, a study says.

Telling these false fossils apart from what could be evidence of ancient life on the surface of Mars—which was temporarily habitable four billion years ago—is key to the success of current and future missions, researchers say.

Astrobiologists from the Universities of Edinburgh and Oxford reviewed evidence of all known processes that could have created lifelike deposits in rocks on Mars.

They identified dozens of processes—with many more likely still undiscovered—that can produce structures that mimic those of microscopic, simple lifeforms that may once have existed on Mars.

Among the lifelike specimens these processes can create are deposits that look like and carbon-based molecules that closely resemble the building blocks of all known life.

Because signs of life can be so closely mimicked by non-living processes, the origins of any fossil-like specimens found on Mars are likely to be very ambiguous, the team says.

They call for greater interdisciplinary research to shed more light on how lifelike deposits could form on Mars, and thereby aid the search for there and elsewhere in the solar system.

The research is published in the Journal of the Geological Society.

Dr. Sean McMahon, Chancellor’s Fellow in Astrobiology at the University of Edinburgh’s School of Physic and Astronomy, said: “At some stage a Mars rover will almost certainly find something that looks a lot like a fossil, so being able to confidently distinguish these from structures and substances made by chemical reactions is vital. For every type of fossil out there, there is at least one non-biological process that creates very similar things, so there is a real need to improve our understanding of how these form.”

Julie Cosmidis, Associate Professor of Geobiology at the University of Oxford, said: “We have been fooled by life-mimicking processes in the past. On many occasions, objects that looked like fossil microbes were described in ancient rocks on Earth and even in meteorites from Mars, but after deeper examination they turned out to have non-biological origins. This article is a cautionary tale in which we call for further research on life-mimicking processes in the context of Mars, so that we avoid falling into the same traps over and over again.”



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