Humans

By Karina Shah
A bone fragment, found in south-east Alaska, belonging to a dog that lived more than 10,000 years ago
Douglas Levere / University at Buffalo
Dogs were domesticated at least 27,000 years ago, and they have been tagging along with humans ever since. Now, we may have the strongest evidence yet that early dogs even accompanied the first Americans as they moved along the Pacific coast.
Charlotte Lindqvist and her colleagues at the University at Buffalo in New York extracted DNA from the oldest known dog remains found in the Americas, and found the genetic signature is consistent with the idea that dogs first arrived in the region between 17,000 and 16,000 years ago – which is also roughly in line with the currently accepted time for the arrival of the first Americans.

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The small bone – a piece of the dome-like head of a thighbone – measures 1 centimetre in diameter and was originally found in the late 1990s in Lawyer’s cave, a site in south-east Alaska.
About 15 years ago it was carbon dated to a little more than 10,000 years old, although at the time the small bone fragment was assumed to have come from a bear. Only when Lindqvist and her colleagues studied DNA from the specimen did they realise it belonged to a dog, which makes it the earliest evidence of dogs found so far in the Americas.
The team isolated mitochondrial DNA from the bone to understand the dog’s genetic history. “The mitochondrial DNA gives us a history of the dog’s mother because it contains maternally inherited DNA,” says Lindqvist.
The DNA sequence showed that the ancient Alaskan dog was closely related to the lineage of domestic dogs that were living in the Americas before European contact and colonisation. In detail, the exact lineage the Alaskan dog belonged to branched off from these “precontact dogs” about 14,500 years ago. The genetic data also showed that the Alaskan dog’s lineage branched off from dogs living in Siberia roughly 16,700 years ago.

“This dog belonged to a descent of very early dogs that moved into the New World soon after the ice age around 17,000 years ago,” says Lindqvist.
Archaeological and genetic evidence suggests humans also moved into the Americas roughly 17,000 years ago – several thousand years earlier than once thought. This has led to a reassessment of how they did so.

Originally it was thought early Americans migrated along an internal corridor between the two large ice sheets that were covering the land after the last peak in glacial activity. This would have seen them enter what is now the lower 48 states of the US via what is now Montana. But this route didn’t become viable to travel through until 13,000 years ago, so the very first Americans must have taken a different route.
Many researchers now think the early Americans travelled along the coast of what is now Alaska and British Columbia, probably because the ice sheet at the North Pacific coast began retreating earlier and provided an ice-free coastal corridor. If dogs also moved into the Americas about 17,000 years ago, they presumably did so with these coastal human communities.
“Humans must have moved over Siberia and Alaska into the New World via a route along the coast, and they brought their dogs with them,” says Lindqvist.
The dog bone found in south-east Alaska is around 250 years older than the previously confirmed earliest dog remains reported from a site in Illinois in 2018. “I am very happy to lose our record for the earliest dogs in the Americas, as this new Alaskan dog represents an important piece of the puzzle,” says Angela Perri at Newcastle University, UK, who led the research in 2018 and wasn’t involved in this new study.
Journal reference: Proceedings of the Royal Society B: Biological Sciences, DOI: 10.1098/rspb.2020.3103
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By Alison George
A colour-enhanced image of the ancient kangaroo artwork
Damien Finch
A life size kangaroo painted in red ochre around 17,300 years ago is Australia’s oldest known rock art. This indicates that the earliest style of rock art in Australia focused on animals, similar to the early cave art found in Indonesia and Europe.
Thousands of rock art sites are found all over Australia, with the Kimberley region of Western Australia containing a particularly rich record. But dating the images is challenging as the minerals and organic material needed to determine when the art was created are hard to find.

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Stylistically, Australian rock art has been categorised into five different phases, with the oldest thought to be the so-called naturalistic phase depicting mainly animals and sometimes plants such as yams. But with no firm dates, no one knew for sure.
Now, Damien Finch at the University of Melbourne and his colleagues have dated the images in eight rock shelters in Balanggarra Country, which lies in the north-eastern Kimberley region. Finch and his colleagues worked with the Balanggarra Aboriginal Corporation, which represents the Traditional Owners of the land, and members of the Corporation reviewed their research paper.
They dated the images by measuring the radiocarbon signal from ancient wasp nests that lie beneath and on top of the artwork.

They discovered that a kangaroo image (pictured above) on the ceiling of a rock shelter containing thousands of ancient mud wasp nests was painted between 17,500 and 17,100 years ago. “This is an amazing site, with wonderful paintings all over the place,” says Finch. And, crucially for the dating, “wasps have been building nests at this site pretty much consistently for 20,000 years“, he says.
This kangaroo painting is around 2 metres long, with details of its fur depicted within an outline of its shape.
“The dating of this oldest known painting in an Australian rock shelter holds a great deal of significance for Aboriginal people and Australians and is an important part of Australia’s history,” said Cissy Gore-Birch, Chair of the Balanggarra Aboriginal Corporation, in a media statement.

Analysis of 15 other images, including a 3-metre-long snake and a lizard-like creature, as well as other kangaroo-like animals, showed that this naturalistic style of animal paintings proliferated between 17,000 and 13,000 years ago.
After this, it seems to have been superseded by the so-called Gwion style of rock art, which predominantly features images of humans. A 2020 study by Finch, also using wasp nest dating, showed that this style of art proliferated from around 12,000 years ago.
The kangaroo is unlikely to be Australia’s oldest painting. Humans may have reached Australia as early as 65,000 years ago and the researchers have studied a tiny number of images in the rock art. “We have only worked on a fraction of the Kimberly. The chances are we haven’t found the oldest painting,” says Finch.
Journal reference: Nature Human Behaviour, DOI: 10.1038/s41562-020-01041-0
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By Priti Parikh
A pit latrine toilet in Kayunga District, Uganda
Sean Sprague/Alamy
Nature sanitises around 38 million tonnes of human waste per year – the equivalent of around £3.2-billion-worth of commercial water treatment.
Alison Parker at Cranfield University in the UK and colleagues looked at 48 cities in Africa, Asia, North America and South America. They analysed how much human waste is produced and where it ends up by reviewing existing data from interviews, observations and direct field measurements.

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The team looked at waste management not connected to sewers. This included pit latrines and septic tanks where waste is primarily contained on-site – in a hole below the ground for pit latrines and in box tanks for septic tanks.
Liquid waste from pit latrines and excess water from septic tanks can gradually filter through soil – a process that cleans it before it reaches groundwater. However, this doesn’t happen in cities where the water table is shallow or where large volumes of waste are discharged in a crowded area. Instead, the liquids can contaminate ground water, posing a health risk.
With 892 million people, predominantly in low and middle income countries, using this type of waste management, the researchers estimate that nature safely treats around 38 million tonnes of human waste per year. The team did not look at how much waste is not safely treated.
More than 4 billion people don’t have access to safe sanitation services, with one-third living in low income countries. Unsafe sanitation is responsible for 775,000 deaths each year.
“Sanitation that involves the ground naturally treating waste can be part of the solution,” says Parker. However, pit latrines, septic tanks and other natural waste management options only work if the soils can filter the waste or if the waste dumped in rivers can be diluted safely without causing harm to the environment, which is not always the case.
Duncan Mara at the University of Leeds, UK, says that approaches like this cannot be the “be-all and end-all” as every person on this planet should be given access to sanitation which is safe for the environment and protects human health. This should include also sewers in crowded areas as they are safer.

Journal reference: Cell Press: One Earth, DOI: S2590-3322(21)00049-X
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By Joshua Rapp Learn
Carbonised barley malt from the Viking Age settlement at Hundborg in northern Jutland
Peter Steen Henriksen/National Museum of Denmark
Ancient malted barley grains have revealed that Danes were likely brewing beer and raising their drinking horns at least two millennia ago.
The oldest known beers in the world trace back to the beginning of agriculture in the Middle East. In Scandinavia, the oldest evidence of beer is based on residue in a bark bucket from roughly 1370 BC which was found in the grave of a Bronze Age teenager known as the Egtved Girl. But chemical analysis shows that beer … More

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Is Capitalism Compatible With Environmentalism asks broadcaster Jon Snow of a panel of experts in climate science, policy and economics at the Science Museum in London. Watch online at 7.30 pm on 26 February.

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Hidden Wonders are revealed by French physicist étienne Guyon and his co-authors in a fascinating book that explores the mathematical elegance in everyday objects and physical mechanisms, from crumpled paper to sandcastles.
Courtesy of EPIX
Watch
Pennyworth, on Amazon Prime Video from 28 February (StarzPlay subscription required), starts its second counterfactual season with Batman’s future butler still in the UK, embroiled in a devastating civil war.
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Curiosity about how well our bodies are ageing has fuelled an industry around telomere length tests, but the much touted “biological clock” in our DNA isn’t what we thought

Life 17 February 2021
By Marta Zaraska
Martin Leon Barreto

WHEN David Nurse turned 30, he wanted to find out how his biological age compared with his chronological one. A life coach with the US National Baseball Association, he hoped that the ultra-healthy lifestyle he advocates to players had kept his own body young and healthy, too. So he took a test to assess the length of his telomeres. It revealed his biological age to be 28 years. That was in 2017. Two years later, he took another test. “I was down to 25, so that was great,” he says.
If you google “telomeres”, you are likely to find them described as an ageing clock. They are segments of DNA at the ends of each chromosome that become shorter every time a cell divides. If this shortening happens slowly, it suggests that your body is wearing well. Say you are a 60-year-old with telomeres as long as those of an average 50-year-old, your mortality risk is equivalent to that of someone 10 years younger – or so the story goes. Increasing numbers of people want this information, and many companies offer tests like the one Nurse took, together with various pills claimed to lengthen your telomeres and, in turn, your lifespan.
If only it were that simple. We are now discovering that telomeres are an unreliable ageing clock, which raises questions about the validity of ageing tests based on them. The links between telomere length and lifestyle choices also aren’t as straightforward as we once thought. In fact, long telomeres can even be bad news. Nevertheless, there are some surprising ways we can look after our … More

By Alison George
The arc of former standing stones at Waun Mawn
A. Stanford
The origins of Stonehenge have long been a mystery. Now new discoveries show that the iconic monument may have started as a stone circle in Wales that was then dismantled and rebuilt 280 kilometres away at its current location on Salisbury plain. This is the conclusion of a team of archaeologists who uncovered the remains of what appears to be Britain’s third-largest stone circle, in the Preseli hills of west Wales.
Stonehenge was built in several different phases between about 3000 and 2000 BC, starting with a large circular ditch and bank together with a circle of 2-metre-high bluestones just inside. Later, these bluestones were moved, and bigger structures made from boulders known as sarsens were built.

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In 2015, a team led by Mike Parker Pearson at University College London revealed that the bluestones were extracted from quarries in the Preseli hills, some 280 kilometres away in west Wales. The team then looked for evidence of stone monuments close to these quarries, as the Neolithic people who extracted Stonehenge’s bluestones might have constructed stone circles here too.
The archaeologists excavated at a site called Waun Mawn, which had four large stones seemingly placed in an arc. They uncovered evidence of a further six holes that each originally held a stone, indicating that there had once been a stone circle with a large diameter at the site.
“The arc did continue – that was a really important moment,” says Parker Pearson. Extrapolating from these positions, the team estimates that the completed circle probably had 30 to 50 stones, though arranged more haphazardly than the original bluestone circle at Stonehenge.

A number of strands of evidence suggest that stones from Waun Mawn formed part of the original stone circle at Stonehenge. Dating studies showed that the Waun Mawn stone circle was created between 3600 and 3200 BC, a few hundred years before the first stages of construction at Stonehenge, and the types of stone at the two sites match.
One of the stone holes at the Welsh site has an unusual pentagonal shape, similar in shape and size to that of bluestone 62 at Stonehenge. “It could have been in that hole. It’s not categorical proof, but it is really very suggestive,” says Parker Pearson.
The sizes of the two circles also match. “There are only two Neolithic monuments in Britain with the same diameter of 110 metres, and that’s the outer ditch of Stonehenge and the Waun Mawn diameter,” he says. Stonehenge is famous for aligning with the midsummer solstice sunrise, and the new evidence at Waun Mawn suggests it had this alignment too.

“It’s a really interesting study that shows some nice arguments for a link between both stone circles,” says David Nash at the University of Brighton, UK, who wasn’t involved with the excavations in Wales, but, who last year published a study identifying the origins of Stonehenge’s sarsens. For him, the clincher would be to conduct detailed geological analysis of stone fragments found at Waun Mawn to see if they are identical to those found at Stonehenge.
Others are less convinced. “They’ve got a ragbag of stones and I’m rather sceptical of it being a stone circle,” says Tim Darvill at Bournemouth University, UK, who has carried out many studies of Stonehenge.
Further excavations are planned at Waun Mawn to clarify the picture. But if Stonehenge was rebuilt from a Welsh stone circle, this could help explain why Neolithic people went to such lengths to construct the iconic megalithic monument. Studies of the isotopes in cremated remains of the earliest people interred at Stonehenge indicate that some of them probably came from west Wales. This has led Parker Pearson to conclude that Stonehenge was constructed to commemorate the ancestors of the original people who lived at Stonehenge.
The Welsh excavations also shed light on the earliest story of the monument’s origins from 1136, when the chronicler Geoffrey of Monmouth wrote how Stonehenge was built from a dismantled stone circle in Ireland. It seems this tale had a grain of truth, says Parker Pearson.
Journal reference: Antiquity, DOI: 10.15184/aqy.2020.239
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By Ibrahim Sawal
These mini brains contain a Neanderthal version of a certain gene
UC San Diego Health Sciences
Miniature brains grown in the lab are helping to reveal how modern humans survived when other hominins died out.
Neanderthals and Denisovans are some of our closest relatives. They lived alongside us about 50,000 years ago when modern humans migrated from Africa towards Europe, but they went extinct shortly after we came into contact with them. This might be because modern humans outcompeted and outsmarted them, but it may have just been bad luck.

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Alysson Muotri at the University of California, San Diego, and his colleagues wanted to know more about how our brains differed from these other hominins and whether this could affect survival. The team compared the genomes of modern humans, Neanderthals and Denisovans and found a total of 61 genes that differed.
One gene, neuro-oncological ventral antigen 1 (NOVA1), particularly caught their eye. The gene is specifically active during brain development and influences the developing nervous system. The team found that the modern human NOVA1 gene differed from the Neanderthal and Denisovan version by a single base pair
To find out more, the team grew their own ancient human-like brains. They used CRISPR genome editing to change the modern NOVA1 gene in human stem cells to mimic the Neanderthal and Denisovan version, then prompted the cells to develop into a Neanderthal or Denisovan-like brain organoid – a small, simplified version of the organ consisting of clusters of brain cells in a dish. They did the same with standard human stem cells.

As they matured, the ancient human organoids were smaller in diameter, had a more wrinkled cell surface and their cells multiplied more slowly than the modern human ones. “They are quite distinct from modern humans, suggesting that single base alteration can change brain development,” says Muotri.
This alteration also changed the expression of 277 genes compared with the modern human organoids, and caused 113 alternative splicing events – a process that causes one gene to code for multiple proteins, many of which were linked to brain development and synapse formations.
“The fact that virtually all modern humans now carry the modern version of the gene, strongly suggests that the alteration is a benefit to our species,” says Muotri. “If I might speculate, it might suggest that individuals carrying the Neanderthal NOVA1 alteration have a potential different way to process information,” he says, and this therefore may have affected their survival.

Tony Capra at the University of California, San Francisco, says he is excited about these new methods because it allows us to directly test Neanderthal brains. “As it progresses, we will be able to evaluate how the Neanderthal genome worked in more and more complex and realistic models,” he says.
However, because Muorti and his team used a modern human genome with a single change, Capra says this doesn’t truly reflect the entire Neanderthal or Denisovan genome. “It is unlikely that a single “magic” genetic change produced a dramatic positive change in these traits,” says Capra. He says there are many parts of our genome that contribute to cognition and that evolution may have acted on multiple variants with smaller effects.
Journal reference: Science, DOI: 10.1126/science.aax2537
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