Humans

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
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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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By Karina Shah

A conch shell found in a cave used by the Magdalenian people of the late Upper Palaeolithic was originally thought to be a cup, but a new analysis suggests they used it as a kind of horn. That would make it the earliest known conch shell horn.
Gilles Tosello at the University of Toulouse in France and his colleagues were investigating objects and cave art found in Marsoulas Cave in the Pyrenees mountains. They revisited a conch shell that was discovered in 1931.
The shell is 31 centimetres long and 18 centimetres wide and once belonged to a large sea snail of the species Charonia lampas that likely lived on the coast of France or Spain.
It has a small narrow hole drilled into the the point of the shell called the apex, and is decorated with fingerprint-shaped ochre red markings.

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“We are pretty sure that this shell was transformed by human action, on the contrary to what was first published in the 1930s,” said Tosello at a press conference on 9 February. Its original discoverers suspected the conch shell was a ceremonial drinking cup.
Tosello and his team came to a different conclusion after examining the inside of the shell with CT scanning and a tiny medical camera.
“The broken part of the apex is very narrow, and the hole inside is perfectly round with a regular edge,” he said. The hole in the apex was most likely drilled to make way for some kind of mouthpiece, such as a small hollow bone to blow into, to protect the lips of the musician.

To test the hypothesis that this was used as an instrument, the team enlisted the help of a horn player to see if they could play the conch shell – the horn player produced three notes close to C, D and C sharp.

Along with the decorative ochre markings – which match paintings found on the walls of the original cave – there are smears of a brown, organic residue around the conch shell. Although there is not enough to determine what the residue is, it was probably used as a sort of glue to fix the mouthpiece into the shell, says Tosello.
The team have now produced a 3D model of the conch shell to investigate how it was used by the Magdalenian people as a musical instrument, without damaging the original artefact.
It’s not surprising that the Magdalenian people played instruments as music is an inherent part of any cultural system, says Francesco d’Errico at the University of Bordeaux in France.
Journal reference: Science Advances, DOI: 10.1126/sciadv.abe9510
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Paul SayedListen
Octave of Light, featuring soprano Beth Sterling, is an album of exoplanet music by David Ibbett, guest composer at Fermilab in Illinois, and astronomer Roy Gould, who have turned exoplanet spectra into musical chords.

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The Raven’s Hat by Jonas Peters and Nicolai Meinshausen is a series of engaging games that seem unsolvable — until you translate them into mathematical terms. Hours of fun for anyone who took maths seriously at school.
Netflix
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Tribes of Europa, a near-future German sci-fi series on Netflix, follows siblings Kiano, Liv, and Elja, who are fighting for their lives on a continent split into warring tribal states. Available from 19 February.
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