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Ancient DNA suggests woolly mammoths roamed Canada more recently than previously thought – National Post

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THE CONVERSATION

This article was originally published on The Conversation, an independent and nonprofit source of news, analysis and commentary from academic experts. Disclosure information is available on the original site.

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Author: Tyler J. Murchie, Postdoctoral fellow, Anthropology, McMaster University

In 2010, small cores of permafrost sediments were collected by a team at the University of Alberta from gold mines in the Klondike region of central Yukon. They had remained in cold storage until paleogeneticists at the McMaster Ancient DNA Centre applied new genomics techniques to better understand the global extinction of megafauna that had culminated in North America some 12,700 years ago.

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These tiny sediment samples contain an immense wealth of ancient environmental DNA from innumerable plants and animals that lived in those environments over millennia. These genetic microfossils originate from all components of an ecosystem — including bacteria, fungi, plants and animals — and serve as a time capsule of long-lost ecosystems, such as the mammoth-steppe, which disappeared around 13,000 years ago.

How exactly these ecosystems restructured so significantly, and why large animals seem to have been the most impacted by this shift has been an active area of scientific debate since the 18th century.

We can now use environmental DNA to help fill the gaps that have driven this debate.

Ancient DNA, cutting-edge technologies

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Bacterial, fungal and unidentifiable DNA make up over 99.99 per cent of an environmental sample. In our case, we wanted a way to selectively recover the much smaller fraction of ancient plant and animal DNA that would help us better understand the collapse of the mammoth-steppe ecosystem.

For my doctoral research, I was part of a team that developed a a new technique to extract, isolate, sequence and identify tiny fragments of ancient DNA from sediment.

We analyzed these DNA fragments to track the shifting cast of plants and animals that lived in central Yukon over the past 30,000 years. We found evidence for the late survival of woolly mammoths and horses in the Klondike region, some 3,000 years later than expected.

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We then expanded our analysis to include 21 previously collected permafrost cores from four sites in the Klondike region that date between 4,000 to 30,000 years ago.

With current technologies, we not only could identify which organisms a set of genetic microfossils came from. But we were also able to reassemble those fragments into genomes to study their evolutionary histories — solely from sediment.

Tremendous environmental change

The Pleistocene-Holocene transition, which occurred about 11,700 years ago, was a period of tremendous change across the globe. In eastern Beringia (the former Eurasian land bridge and unglaciated regions of Yukon and Alaska), this period saw the collapse of the mammoth-steppe biome and its gradual replacement with the boreal forest as we know it today.

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This brought about the loss of iconic ice age megaherbivores like the woolly mammoth, Yukon horse, and steppe bison, along with predators such as the American scimitar cat and Beringian lion, among many others.

We found ancient environmental DNA from a diverse spectrum of ancient fauna, including woolly mammoths, horses, steppe bison, caribou, rodents, birds and many other animals.

We were also able to observe how ecosystems shifted with the rise of woody shrubs around 13,500 years ago, and how that correlated with a decline of DNA from woolly mammoths, horses and steppe bison. With this remarkably rich dataset, we observed four main findings.

1. There was a surprising consistency in the signal between sites, suggesting our data was representative of ecological trends in the region.

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2 . Woolly mammoth DNA declines prior to the Bølling–Allerød warming, a warm period at the end of the last ice age, suggesting that megafaunal losses may have been staggered.

3. Forbs (herbaceous flowering plants) make up a substantial component of the mammoth-steppe ecosystem alongside grasses.

4. There is a consistent signal of woolly mammoth and Yukon horse persistence into the Holocene, as much as 7,000 years after their disappearance from fossil records.

When paired with other records, our genetic reconstructions suggest that the transition out of the last glacial period may have been more drawn out than dated bones alone would suggest.

Mammoths, for example, may have declined in local population abundance thousands of years earlier than other megafauna, which is potentially correlated with the first controversial evidence of humans in the area. Further, grassland grazing animals may have persisted for thousands of years in refugia (habitats that support the existence of an isolated population), despite the environmental shift.

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Woolly mammoths alongside humans

Our data suggest that horses and woolly mammoths may have persisted in the Klondike until approximately 9,000 years ago and perhaps as recently as 5,700 years ago, outliving their supposed disappearance from local fossil records by 7,000 years. However, it is possible for ancient environmental DNA to survive erosion and re-deposition, which could mix the genetic signals of different time periods, necessitating a degree of caution in our interpretations.

Until recently, there was no evidence of mammoth survival into the mid-Holocene. But studies have now shown that mammoths survived until 5,500 and 4,000 years ago on Arctic islands.

Researchers at the Centre for GeoGenetics in Copenhagen found evidence for the late survival of horses and mammoths in Alaska until as recently as as 7,900 years ago. They also found evidence of mammoths surviving as recently as 3,900 years ago in Siberia, alongside woolly rhinoceros to at least 9,800 years ago.

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Steppe bison, which were thought to have disappeared and been replaced by the American bison during the Pleistocene, have likewise been found to have survived even as recently as perhaps just 400 years ago. We were able to observe the presence of distinct genetic lineages of both woolly mammoths and steppe bison in the same sediment samples, which suggests that there were likely distinct populations of these animals living in the same area.

There is a growing body of evidence that many ice age megafauna probably survived well into recorded human history, roaming the north during the Bronze Age and while builders worked on the pyramids of Egypt.

Genetic archives of our ecological past

The growing sophistication of environmental DNA methods to study ancient genetic microfossils highlights just how much information is buried in sediments.

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Permafrost is ideal for preserving ancient DNA, but as this perennially frozen ground thaws and degrades with a warming Arctic, so too will the genetic material preserved within, and the evolutionary mysteries they once held.

Advances in paleogenetics continues to push the boundaries of what was once relegated to science fiction. Who knows what undiscovered evolutionary information remains frozen in ordinary sediments, hidden in microfossils of ancient DNA?

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Tyler J. Murchie currently receives funding from the CANA Foundation, a non-profit organization with horse rewilding initiatives.

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This article is republished from The Conversation under a Creative Commons license. Disclosure information is available on the original site. Read the original article: https://theconversation.com/ancient-dna-suggests-woolly-mammoths-roa https://theconversation.com/ancient-dna-suggests-woolly-ma

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Fluid in eye cells can 'boil' if you watch the eclipse without protection: expert – Delta Optimist

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Millions of people in parts of Eastern and Atlantic Canada will be able to see the rare solar eclipse happening on April 8. But they should only look up if they have proper eye protection, experts say. 

WHY IS WATCHING THE ECLIPSE MORE DANGEROUS THAN LOOKING AT THE SUN ON A NORMAL DAY?

When people look up at the sun normally, the intense brightness triggers pain that causes them to look away quickly before it can cause damage, said Dr. Philip Hooper, president of the Canadian Ophthalmological Society.

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But as the moon starts to block the sun in the period leading up to the total eclipse “there is significant light energy that’s coming from the sun, but we don’t appreciate pain. And so you can look at it long enough to do damage to the eye,” said Hooper, who is also an associate professor of ophthalmology at Western University in London, Ont. 

HOW DOES STARING AT THE SUN DAMAGE OUR EYES?

When you’re looking directly at the sun, intense visible light and infrared radiation are focused on the centre of the retina in the back of the eye. 

“It’s basically like taking a magnifying glass in the sun on a normal day and focusing that light on a piece of paper. It can get hot enough to burn the paper,” Hooper said. 

The sun has the same effect, because your eye concentrates that energy into a small area of the retina. 

“The temperature of the cells in that area can actually get high enough that the fluid in the cells actually boils and it damages the cells permanently,” he said. 

CAN I JUST PUT MY SUNGLASSES ON TO WATCH THE ECLIPSE?

No. Sunglasses do not provide protection, Hooper said. 

WHAT IF I STAY INSIDE AND WATCH THROUGH THE WINDOW?

Again, no. Windows offer no protection. 

IS IT SAFE TO WATCH THROUGH A PHONE CAMERA?

No.

“Eclipse or not, you shouldn’t look at the sun directly with the naked eye, or with a camera or telescope, without a (certified) solar filter. This can lead to irreversible eye damage,” says an eclipse safety video posted online by the Canadian Space Agency. 

Pointing your phone camera directly at the eclipse may also have other consequences. 

“Just remember that your camera on your phone has lenses just like eyeglasses do, and that light is coming in from the sun as soon as you open the shutter,” said Elaina Hyde, director of the Allan I. Carswell Observatory at York University in Toronto.

“At the very least you could expect to damage your camera. You won’t be able to see anything, again, because your phone is not able to handle that light.”

HOW DO I SAFELY WATCH THE ECLIPSE?

You’ll need special glasses with filters designed for eclipse watching, says the Canadian Space Agency website. 

Those glasses must have side protection so that light rays can’t enter, said Hooper. 

They must also have certified lenses, he said.

The certificationISO 12312-2 should be printed on the glasses, whichmeans the glasses meet international safety standards.  

While wearing the glasses, you should not be able to see anything unless you’re staring at the sun. 

“No matter how bright a light you are exposed to in your indoor environment, if you shone a very bright light through them, you’d see nothing. They’re totally black. That’s how dark they are,” Hooper said. 

The eclipse glasses should not be used if they are “scratched, punctured, torn, or otherwise damaged,” the American Astronomical Society says on its website, noting that people should inspect their glasses before using them. 

The society also says that children using the glasses during the eclipse must be supervised at all times. 

WHERE CAN I GET THE ISO 12312-2 CERTIFIED GLASSES?

Free eclipse-viewing glasses are available at many libraries, cities and school districts across Canada, according to the Royal Astronomical Society of Canada website.   

The American Astronomical Society has a list of companies and retailers in both Canada and the U.S. that sell certified solar eclipse glasses on its website.  

Some companies selling them in Quebec are listed on the Eclipse Quebec website. 

WHAT ABOUT WELDING GOGGLES?

Welding goggles come in a variety of shades, denoted by number, according to the Canadian Centre for Occupational Health and Safety website. 

The minimum darkness required to safely watch the eclipse is shade 13, said Hooper. 

“That’s much darker than the welding glasses or goggles that are typically used by welders. And they’re not widely available,” he said. 

IF I DON’T HAVE THE CERTIFIED GLASSES, IS THERE ANOTHER OPTION?

Another option for safe viewing is to make a projector so that you are never looking directly at the sun. It can be as basic as a piece of paper with a pinhole that projects the light from the sun onto the sidewalk, or a projector made out of a box. 

The Canadian Space Agency website has simple instructions on how to make a projector using an empty cardboard box, a sheet of white paper, aluminum foil, a pin, tape and scissors.  

For instructions, visit https://www.asc-csa.gc.ca/eng/youth-educators/activities/fun-experiments/eclipse-projector.asp 

-With files from Sonja Puzic

This report by The Canadian Press was first published March 29, 2024.

Canadian Press health coverage receives support through a partnership with the Canadian Medical Association. CP is solely responsible for this content.

Nicole Ireland, The Canadian Press

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The total solar eclipse in North America could shed light on a persistent puzzle about the sun – Phys.org

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The total solar eclipse in North America could shed light on a persistent puzzle about the sun

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The path of eclipse totality passes through Mexico, the US and Canada. Credit: NASA’s Scientific Visualization Studio

A total solar eclipse takes place on April 8 across North America. These events occur when the moon passes between the sun and Earth, completely blocking the sun’s face. This plunges observers into a darkness similar to dawn or dusk.

During the upcoming eclipse, the path of totality, where observers experience the darkest part of the moon’s shadow (the umbra), crosses Mexico, arcing north-east through Texas, the Midwest and briefly entering Canada before ending in Maine.

Total solar eclipses occur roughly every 18 months at some location on Earth. The last that crossed the US took place on August 21 2017.

An international team of scientists, led by Aberystwyth University, will be conducting experiments from near Dallas, at a location in the path of totality. The team consists of Ph.D. students and researchers from Aberystwyth University, Nasa Goddard Space Flight Center in Maryland, and Caltech (California Institute of Technology) in Pasadena.

There is valuable science to be done during eclipses that is comparable to or better than what we can achieve via space-based missions. Our experiments may also shed light on a longstanding puzzle about the outermost part of the sun’s atmosphere—its corona.

The sun’s intense light is blocked by the moon during a total solar eclipse. This means that we can observe the sun’s faint corona with incredible clarity, from distances very close to the sun, out to several solar radii. One radius is the distance equivalent to half the sun’s diameter, about 696,000km (432,000 miles).

Measuring the corona is extremely difficult without an eclipse. It requires a special telescope called a coronagraph that is designed to block out direct light from the sun. This allows fainter light from the corona to be resolved. The clarity of eclipse measurements surpasses even coronagraphs based in space.

We can also observe the corona on a relatively small budget, compared to, for example, spacecraft missions. A persistent puzzle about the corona is the observation that it is much hotter than the photosphere (the visible surface of the sun). As we move away from a hot object, the surrounding temperature should decrease, not increase. How the corona is heated to such high temperatures is one question we will investigate.

We have two main scientific instruments. The first of these is Cip (coronal imaging polarimeter). Cip is also the Welsh word for “glance,” or “quick look.” The instrument takes images of the sun’s corona with a polariser.

The light we want to measure from the corona is highly polarized, which means it is made up of waves that vibrate in a single geometric plane. A polarizer is a filter that lets light with a particular polarization pass through it, while blocking light with other polarizations.

The Cip images will allow us to measure fundamental properties of the corona, such as its density. It will also shed light on phenomena such as the solar wind. This is a stream of sub-atomic particles in the form of plasma—superheated matter—flowing continuously outward from the sun. Cip could help us identify sources in the sun’s atmosphere for certain solar wind streams.

Direct measurements of the magnetic field in the sun’s atmosphere are difficult. But the eclipse data should allow us to study its fine-scale structure and trace the field’s direction. We’ll be able to see how far magnetic structures called large “closed” magnetic loops extend from the sun. This in turn will give us information about large-scale magnetic conditions in the corona.

The second instrument is Chils (coronal high-resolution line spectrometer). It collects high-resolution spectra, where light is separated into its component colors. Here, we are looking for a particular spectral signature of iron emitted from the corona.

It comprises three , where light is emitted or absorbed in a narrow frequency range. These are each generated at a different range of temperatures (in the millions of degrees), so their relative brightness tells us about the coronal temperature in different regions.

Mapping the ‘s temperature informs advanced, computer-based models of its behavior. These models must include mechanisms for how the coronal plasma is heated to such high temperatures. Such mechanisms might include the conversion of magnetic waves to thermal plasma energy, for example. If we show that some regions are hotter than others, this can be replicated in models.

This year’s eclipse also occurs during a time of heightened solar activity, so we could observe a coronal mass ejection (CME). These are huge clouds of magnetized plasma that are ejected from the sun’s atmosphere into space. They can affect infrastructure near Earth, causing problems for vital satellites.

Many aspects of CMEs are poorly understood, including their early evolution near the sun. Spectral information on CMEs will allow us to gain information on their thermodynamics, and their velocity and expansion near the sun.

Our eclipse instruments have recently been proposed for a space mission called moon-enabled solar occultation mission (Mesom). The plan is to orbit the moon to gain more frequent and extended eclipse observations. It is being planned as a UK Space Agency mission involving several countries, but led by University College London, the University of Surrey and Aberystwyth University.

We will also have an advanced commercial 360-degree camera to collect video of the April 8 eclipse and the observing site. The video is valuable for public outreach events, where we highlight the work we do, and helps to generate public interest in our local star, the sun.

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The total solar eclipse in North America could shed light on a persistent puzzle about the sun (2024, March 28)
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Mar 30: An Australian Atlantis and other lost landscapes, and more… – CBC.ca

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Quirks and Quarks54:00An Australian Atlantis and other lost landscapes, and more…


On this week’s episode of Quirks & Quarks with Bob McDonald: 

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Archaeologists identify a medieval war-horse graveyard near Buckingham Palace 

Quirks and Quarks9:04Archaeologists identify a medieval war-horse graveyard near Buckingham Palace

We know knights in shining armour rode powerful horses, but remains of those horses are rare. Now, researchers studying equine remains from a site near Buckingham Palace have built a case, based on evidence from their bones, that these animals were likely used in jousting tournaments and battle. Archaeologist Katherine Kanne says the bone analysis also revealed a complex, continent-crossing medieval horse trading network that supplied the British elite with sturdy stallions. This paper was published in Science Advances.

University of Exeter researchers analyzed horse skeletons found near Buckingham Palace and conducted isotope tests on teeth to find out more about the animals’ origins. (University of Exeter)

In an ice-free Arctic, polar bears are dining on duck eggs — and gulls are taking advantage

Quirks and Quarks9:22In an ice-free Arctic, Polar bears are dining on duck eggs — and gulls are taking advantage

Researchers using drones to study ground-nesting birds in the Arctic have observed entire colonies being devastated by marauding polar bears that would normally be out on the ice hunting seals, except the ice isn’t there. What’s more, now they’re enabling a second predator — hungry gulls that raid the nests in the bears’ wake. Andrew Barnas made the observations of this “gull tornado” by following around polar bears in East Bay Island in Nunavut. The research was published in the journal Ecology and Evolution.

Aerial video of a polar bear on grassy, rocky terrain with white birds circling nearby.
A polar bear storms eider duck nests on East Bay island in Nunavut, while herring gulls follow closely behind to snack on any remaining eggs. (Submitted by Andrew Barnas)

A NASA mission might have the tools to detect life on Europa from space

Quirks and Quarks8:05A NASA mission might have the tools to detect life on Europa from space

NASA’s Europa Clipper mission, due to launch this fall, is set to explore the jewel of our solar system: Jupiter’s moon, Europa. The mission’s focus is to determine if the icy moon, thought to harbour an ocean with more water than all of the water on Earth, is amenable to life. However, postdoctoral researcher Fabian Klenner, now at the University of Washington, demonstrated how the spacecraft may be able to detect fragments of bacterial life in a single grain of ice ejected from the surface of the moon. The study was published in the journal Science Advances.

The silhouette of the spacecraft is flying over a brightly pink, blue and orange tinted moon with lots of darker coloured veins underneath with a slightly eclipsed Jupiter looming in the backdrop.
Scientists think under Europa’s icy shell, there is a global, saltwater ocean with twice the volume of Earth’s oceans combined. (NASA/Jet Propulsion Laboratory/Caltech)

Pollution is preventing pollinators from recognizing floral plants by scent

Quirks and Quarks7:50Pollution is preventing pollinators from finding plants by scent

Our polluted air is transforming floral scents so pollinators that spread their pollen can no longer recognize them. In a new study in the journal Science, researchers found that a certain compound in air pollution reacts with the flower’s scent molecules so pollinators — like the hummingbird hawk-moths that pollinate at night — fail to recognize them. Jeremy Chan, a postdoctoral researcher at the University of Naples, said the change in scent made the flowers smell “less fruity and less fresh.”

A huge insect that looks like a hummingbird hovers over a vibrant pink flower with its long antenna inside one of the blooms.
Scientists found that a hummingbird hawk-moth’s ability to recognize the smell of flowers is hampered by air pollution. (Thomas Kienzle/AFP/Getty Images)

An Australian Atlantis and underwater archeological remains in the Baltic 

Quirks and Quarks17:14An Australian Atlantis and underwater archeological remains in the Baltic

During the last ice age, sea levels were more than 100 metres lower than they are today, which means vast tracts of what are currently coastal seafloor were dry land back then. Geologists and archaeologists are searching for these lost landscapes to identify places prehistoric humans might have occupied. These included a country-sized area of Australia that could have been home to half a million people. Archaeologist Kasih Norman and her colleagues published their study of this now-drowned landscape in Quaternary Science Reviews

Another example is an undersea wall off the coast of Northern Germany that preserves an underwater reindeer hunting ground, described in research led by Jacob Geersen, published in the journal PNAS.

a black-and-white depiction of a small group of caribou walking between a low stone wall and an ocean coastline.
An artist’s representation of caribou being directed by a hunters’ stone wall, as it would have appeared 8-11,000 years ago, before rising sea levels left it 20m below the surface of the Baltic Sea. (Michał Grabowski)

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