
New Bone Test Could Rewrite British History
From the end of the Roman occupation through the Anglo-Saxon and Viking invasions - a new way of testing DNA in ancient bones could force a rethink of key moments in Britain's early history, say researchers.
Scientists could already track big alterations in DNA that occur over thousands or millions of years, helping us learn, for example, how early humans evolved from ape-like creatures.
Now researchers can identify subtler changes over just hundreds of years, providing clues as to how people migrated and interacted with locals.
They are using the new method to analyse human remains found in Britain, including from the time when Romans were replaced by an Anglo-Saxon elite from Europe.
Prof Peter Heather, from Kings College London, who is working on the project with the developers of the new DNA technique at the Francis Crick Institute in London, said the new technique could be "revolutionary".
While the project will analyse the DNA of more than 1,000 ancient human remains of people who lived in Britain during the past 4,500 years, researchers have homed in on the time after the Romans left as a particularly interesting era to study.
What happened in this period more than 1,500 years ago is unclear from written and archeological records. Historians are divided in their views about the scale and nature of the Anglo-Saxon invasion, whether it was large or small, hostile or co-operative.
"It is one of the most contested and therefore one of the most exciting things to work on in the whole of British history," according to Prof Heather.
"[The new method] will allow us to see the type of relations that are being found with the native population," he said. "Are they co-operative, is there interbreeding, are the locals able to make their way into the elite?"
They are optimistic about the success of the technique, known as Twigstats, after testing it on human remains found in mainland Europe between the years 1 and 1,000 CE.
Much of what they gleaned from the DNA about the spread of the Vikings into Scandinavia tallied with historical records.
This result, published in the journal Nature, confirmed the method worked while showing how powerful it could be at shedding new light on accepted facts when findings didn't match what was written in the history books.
"That was the moment we got really excited," said Dr Leo Speidel, who developed the technique with his group leader Dr Pontus Skoglund. "We could see that this could really change how much we can find out about human history."
The problem the researchers were trying to overcome is that a human's genetic code is extremely long - consisting of 3 billion separate chemical units.
Spotting the small genetic changes in that code which occur over a few generations, for example, as a result of new arrivals interbreeding with the local population, is like looking for a needle in a haystack.
The researchers solved the problem by, as it were, taking away the haystack and leaving the needle in plain sight - they found a way to identify the older genetic changes, disregard them and look only at the most recent alterations.
They combed the genetic data of thousands of human remains from an online scientific database, then calculated how closely they were related to each other, which chunks of DNA were inherited from which groups and when.
This created a family tree with older changes appearing in earlier branches, and more recent changes showing up in newer 'twigs', hence the name Twigstats.
Each of the people whose remains will be studied have their own tales to tell and soon scientists and historians will be able to hear their stories, said Dr Skoglund.
"We want to understand many different epochs in European and British history, from the Roman period, when the Anglo-Saxons arrived, through the Viking period and see how this shapes the ancestry and diversity of this part of the World," he said.
As well as showing up interbreeding with different populations, embedded in the ancient DNA are hugely important details on how people coped with key historical moments, such epidemics, shifts in diet, urbanisation, and industrialisation.
The technique can potentially be applied to any part of the world for which there are a large collection of well preserved human remains.
Prof Heather wants to use it to investigate what he describes as one of European history's biggest mysteries: why central and eastern Europe changed from being Germanic speaking to Slavic speaking, 1,500 years ago.
"Historical sources show what was the case before and what was the case after, but there is nothing about what happened in between," he said.
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Nahar Net
30-05-2025
- Nahar Net
What would happen if the Amazon rainforest dried out?
by Naharnet Newsdesk 30 May 2025, 16:34 A short walk beneath the dense Amazon canopy, the forest abruptly opens up. Fallen logs are rotting, the trees grow sparser and the temperature rises in places sunlight hits the ground. This is what 24 years of severe drought looks like in the world's largest rainforest. But this patch of degraded forest, about the size of a soccer field, is a scientific experiment. Launched in 2000 by Brazilian and British scientists, Esecaflor — short for "Forest Drought Study Project" in Portuguese— set out to simulate a future in which the changing climate could deplete the Amazon of rainfall. It is the longest-running project of its kind in the world, and has become a source for dozens of academic articles in fields ranging from meteorology to ecology and physiology. Understanding how drought can affect the Amazon, an area twice the size of India that crosses into several South American nations, has implications far beyond the region. The rainforest stores a massive amount of carbon dioxide, a greenhouse gas that is the main driver of climate change. According to one study, the Amazon stores the equivalent of two years of global carbon emissions, which mainly come from the burning of coal, oil and gasoline. When trees are cut, or wither and die from drought, they release into the atmosphere the carbon they were storing, which accelerates global warming. Creating drought conditions and observing the results To mimic stress from drought, the project, located in the Caxiuana National Forest, assembled about 6,000 transparent plastic rectangular panels across one hectare (2.5 acres), diverting around 50% of the rainfall from the forest floor. They were set 1 meter above ground (3.3 ft) on the sides to 4 meters (13.1 ft) above ground in the center. The water was funneled into gutters and channeled through trenches dug around the plot's perimeter. Next to it, an identical plot was left untouched to serve as a control. In both areas, instruments were attached to trees, placed on the ground and buried to measure soil moisture, air temperature, tree growth, sap flow and root development, among other data. Two metal towers sit above each plot. In each tower, NASA radars measure how much water is in the plants, which helps researchers understand overall forest stress. The data is sent to the space agency's Jet Propulsion Laboratory in California, where it is processed. "The forest initially appeared to be resistant to the drought," said Lucy Rowland, an ecology professor at the University of Exeter. That began to change about 8 years in, however. "We saw a really big decline in biomass, big losses and mortality of the largest trees," said Rowland. This resulted in the loss of approximately 40% of the total weight of the vegetation and the carbon stored within it from the plot. The main findings were detailed in a study published in May in the journal Nature Ecology & Evolution. It shows that during the years of vegetation loss, the rainforest shifted from a carbon sink, that is, a storer of carbon dioxide, to a carbon emitter, before eventually stabilizing. There was one piece of good news: the decades-long drought didn't turn the rainforest into a savanna, or large grassy plain, as earlier model-based studies had predicted. Next steps include measuring forest recovery In November, most of the 6,000 transparent plastic covers were removed, and now scientists are observing how the forest changes. There is currently no end date for the project. "The forest has already adapted. Now we want to understand what happens next," said meteorologist João de Athaydes, vice coordinator of Esecaflor, a professor at the Federal University of Para and coauthor of the Nature study. "The idea is to see whether the forest can regenerate and return to the baseline from when we started the project." During a visit in April, Athaydes guided Associated Press journalists through the site, which had many researchers. The area was so remote that most researchers had endured a full-day boat trip from the city of Belem, which will host the next annual U.N. climate talks later this year. During the days in the field, the scientists stayed at the Ferreira Penna Scientific Base of the Emilio Goeldi Museum, a few hundred yards (meters) from the plots. Four teams were at work. One collected soil samples to measure root growth in the top layer. Another gathered weather data and tracking soil temperature and moisture. A third was measured vegetation moisture and sap flow. The fourt focused on plant physiology. "We know very little about how drought influences soil processes," said ecologist Rachel Selman, researcher at the University of Edinburgh and one of the co-authors of the Nature study, during a break. Esecaflor's drought simulation draws some parallels with the past two years, when much of the Amazon rainforest, under the influence of El Nino and the impact of climate change, endured its most severe dry spells on record. The devastating consequences ranged from the death of dozens of river dolphins due to warming and receding waters to vast wildfires in old-growth areas. Rowland explained that the recent El Nino brought short-term, intense impacts to the Amazon, not just through reduced rainfall but also with spikes in temperature and vapor pressure deficit, a measure of how dry the air is. In contrast, the Esecaflor experiment focused only on manipulating soil moisture to study the effects of long-term shifts in rainfall. "But in both cases, we're seeing a loss of the forest's ability to absorb carbon," she said. "Instead, carbon is being released back into the atmosphere, along with the loss of forest cover."


MTV Lebanon
04-03-2025
- MTV Lebanon
World's largest iceberg runs aground off remote island
The world's largest iceberg has run aground in shallow waters off the remote British island of South Georgia, home to millions of penguins and seals. The iceberg, which is about twice the size of Greater London, appears to be stuck and should start breaking up on the island's south-west shores. Fisherman fear they will be forced to battle with vast chunks of ice, and it could affect some macaroni penguins feeding in the area. But scientists in Antarctica say that huge amounts of nutrients are locked inside the ice, and that as it melts, it could create an explosion of life in the ocean. "It's like dropping a nutrient bomb into the middle of an empty desert," says Prof Nadine Johnston from British Antarctic Survey. Ecologist Mark Belchier who advises the South Georgia government said: "If it breaks up, the resulting icebergs are likely to present a hazard to vessels as they move in the local currents and could restrict vessels' access to local fishing grounds." The stranding is the latest twist in an almost 40-year story that began when the mega chunk of ice broke off the Filchner–Ronne Ice Shelf in 1986. We have tracked its route on satellite pictures since December when it finally broke free after being trapped in an ocean vortex. As it moved north through warmer waters nicknamed iceberg alley, it remained remarkably intact. For a few days, it even appeared to spin on the spot, before speeding up in mid-February travelling at about 20 miles (30km) a day. "The future of all icebergs is that they will die. It's very surprising to see that A23a has lasted this long and only lost about a quarter of its area," said Prof Huw Griffiths, speaking to BBC News from the Sir David Attenborough polar research ship currently in Antarctica. On Saturday the 300m tall ice colossus struck the shallow continental shelf about 50 miles (80km) from land and now appears to be firmly lodged. "It's probably going to stay more or less where it is, until chunks break off," says Prof Andrew Meijers from British Antarctic Survey. It is showing advancing signs of decay. Once 3,900 sq km (1,500 sq miles) in size, it has been steadily shrinking, shedding huge amounts of water as it moves into warmer seas. It is now an estimated 3,234 sq km. "Instead of a big, sheer pristine box of ice, you can see caverns under the edges," Prof Meijers says. Tides will now be lifting it up and down, and where it is touching the continental shelf, it will grind backwards and forwards, eroding the rock and ice. "If the ice underneath is rotten - eroded by salt - it'll crumble away under stress and maybe drift somewhere more shallow," says Prof Meijers. But where the ice is touching the shelf, there are thousands of tiny creatures like coral, sea slugs and sponge. "Their entire universe is being bulldozed by a massive slab of ice scraping along the sea floor," says Prof Griffiths. That is catastrophic in the short-term for these species, but he says that it is a natural part of the life cycle in the region. "Where it is destroying something in one place, it's providing nutrients and food in other places," he adds. There had been fears for the islands' larger creatures. In 2004 an iceberg in a different area called the Ross Sea affected the breeding success of penguins, leading to a spike in deaths. But experts now think that most of South Georgia's birds and animals will escape that fate. Some Macaroni penguins that forage on the shelf where the iceberg is stuck could be affected, says Peter Fretwell at the British Antarctic Survey. The iceberg melts freshwater into salt water, reducing the amount of food including krill (a small crustacean) that penguins eat. The birds could move to other feeding grounds, he explains, but that would put them in competition with other creatures. The ice could block harbours or disrupt sailing when the fishing season starts in April. "We will have to do battle with A23a for sure," says Andrew Newman from Argos Froyanes. But scientists working in Antarctica currently are also discovering the incredible contributions that icebergs make to ocean life. Prof Griffiths and Prof Johnston are working on the Sir David Attenborough ship collecting evidence of what their team believe is a huge flow of nutrients from ice in Antarctica across Earth. Particles and nutrients from around the world get trapped into the ice, which is then slowly released into the ocean, the scientists explain. "Without ice, we wouldn't have these ecosystems. They are some of the most productive in the world, and support huge numbers of species and individual animals, and feed the biggest animals in the world like the blue whale," says Prof Griffiths. A sign that this nutrient release has started around A23a will be when vast phytoplankton blooms blossom around the iceberg. It would look like a vast green halo around the ice, visible from satellite pictures over the next weeks and months. The life cycle of icebergs is a natural process, but climate change is expected to create more icebergs as Antarctica warms and becomes more unstable. More could break away from the continent's vast ice sheets and melt at quicker rates, disrupting patterns of wildlife and fishing in the region.


Nahar Net
21-02-2025
- Nahar Net
Climate change is shrinking glaciers faster than ever, with 7 trillion tons lost since 2000
by Naharnet Newsdesk 21 February 2025, 14:35 Climate change is accelerating the melting of the world's mountain glaciers, according to a massive new study that found them shrinking more than twice as fast as in the early 2000s. The world's glaciers lost ice at the rate of about 255 billion tons (231 billion metric tons) annual from 2000 to 2011, but that quickened to about 346 billion tons (314 billion metric tons) annually over about the next decade, according to the study in this week's journal Nature. And the last few years, the melt has accelerated even more, hitting a record 604 billion tons (548 billion metric tons) lost in 2023, the last year analyzed. The study drew on an international effort that included 233 estimates of changes in glacier weight. In all, the world's glaciers have lost more than 7 trillion tons of ice (6.5 trillion metric tons) since 2000, according to the study. "The thing that people should be aware of and perhaps worried about is that yes, the glaciers are indeed retreating and disappearing as we said they would. The rate of that loss seems to be accelerating," said William Colgan, a glaciologist for the Geological Survey of Denmark and Greenland and one of about 60 authors of the study. Glaciers in Alaska are melting at the fastest rate of any of the 19 regions studied, losing about 67 billion tons (61 billion metric tons) of ice a year, producing the biggest net ice loss, the study found. In the past 24 years, Central Europe's glaciers have lost the highest percentage of ice of any region, now 39% smaller than they were in 2000, the paper said. Colgan said he worries most about the Alps because "elevated summer temperatures have been hammering the Alps. " Fifteen years ago, scientists were worried most about the Andes and the Patagonia glaciers, but the Alps have shrunk so fast they could eventually disappear, Colgan said. "Glaciers are apolitical and unbiased sentinels of climate change, and their decline paints a clear picture of accelerated warming," said Gwenn Flowers, a professor of Earth Sciences at Simon Fraser University in Canada, who wasn't part of the study. University of Colorado ice scientist Ted Scambos, who also wasn't part of the study, said glaciers shrank and grew in the past for local, well-understood reasons that were not climate change. What's happening now is different and clear, he said: "It's due to greenhouse gas increases caused directly by coal, oil, and natural gas burning. ... No amount of rhetoric, tweeting, or proclamation will change that." Scambos, Flowers and other outside scientists called the assessment sobering and accurate but not surprising. Colgan said that many places — such as those in the U.S. West — are seeing extra water now from fast-melting glaciers and benefiting from that boost, but that will soon disappear as the glaciers melt beyond a point of no return. Melting glaciers contribute more to sea level rise than ice loss in either Greenland or Antarctica. Only the expansion of water as it warms plays a bigger role in sea level rise, the paper said. The overall glacier loss rate is similar, if maybe slightly less, than that found by earlier and less comprehensive studies. But this new work will probably trigger new predictions that will be even gloomier in the future because of better information and worsening warming, Colgan said. "If you're losing 5.5% of the global ice volume in just over 20 years, clearly that's not sustainable," Colgan said. "That's going to catch up with you." The more than 600 billion tons of glacier loss in 2023 "sounds incredible now, but it might sound pretty normal in 10 years from now," Colgan said. "Mountain glaciers as a whole can flip into collective ice loss pretty darn quick."