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      New effort IDs the genes that made the mammoth

      news.movim.eu / ArsTechnica · Friday, 7 April, 2023 - 17:40 · 1 minute

    Artist's view of a mammoth superimposed over DNA sequencing data.

    Enlarge (credit: Beth Zaiken)

    An international team of scientists has published the results of their research into 23 woolly mammoth genomes in Current Biology . As of today, we have even more tantalizing insights into their evolution, including indications that, while the woolly mammoth was already predisposed to life in a cold environment, it continued to make further adaptations throughout its existence.

    Years of research, as well as multiple woolly mammoth specimens, enabled the team to build a better picture of how this species adapted to the cold tundra it called home. Perhaps most significantly, they included a genome they had previously sequenced from a woolly mammoth that lived 700,000 years ago, around the time its species initially branched off from other types of mammoth. Ultimately, the team compared that to a remarkable 51 genomes—16 of which are new woolly mammoth genomes: the aforementioned genome from Chukochya, 22 woolly mammoth genomes from the Late Quaternary, one genome of an American mastodon (a relative of mammoths), and 28 genomes from extant Asian and African elephants.

    From that dataset, they were able to find more than 3,000 genes specific to the woolly mammoth. And from there, they focused on genes where all the woolly mammoths carried sequences that altered the protein compared to the version found in their relatives. In other words, genes where changes appear to have been naturally selected.

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      By eating them, hyenas gathered 9 Neanderthal skeletons in one cave

      Kiona N. Smith · news.movim.eu / ArsTechnica · Monday, 10 May, 2021 - 18:18

    By eating them, hyenas gathered 9 Neanderthal skeletons in one cave

    Enlarge (credit: Italian Culture Ministry)

    Archaeologists in Italy recently unearthed the remains of at least nine Neanderthals in Guattari Cave, near the Tyrrhenian Sea about 100 km southeast of Rome. While excavating a previously unexplored section of the cave, archaeologists from the Archaeological Superintendency of Latina and the University of Tor Vergata recently unearthed broken skulls, jawbones, teeth, and pieces of several other bones, which they say represent at least nine Neanderthals. That brings the cave’s total to at least 10; anthropologist Alberto Carlo Blanc found a Neanderthal skull in another chamber in 1939.

    Italy was a very different place 60,000 years ago. Hyenas, along with other Pleistocene carnivores, stalked rhinoceroses, wild horses (an extinct wild bovine called aurochs), and people.

    “Neanderthals were prey for these animals. Hyenas hunted them, especially the most vulnerable, like sick or elderly individuals,” Tor Vergata University archaeologist Mario Rolfo told The Guardian. The archaeologists found the Neanderthal remains mingled with the bones of rhinos, giant deer, wild horses, and other hyenas. Predators and scavengers tend to leave behind different parts of the skeleton than, say, flowing water or simple burial—and tooth marks are usually a dead giveaway.

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      Million-year-old mammoth DNA rewrites animal’s evolutionary tree

      John Timmer · news.movim.eu / ArsTechnica · Wednesday, 17 February, 2021 - 18:10 · 1 minute

    Image of a fractured, white post partially embedded in the soil.

    Enlarge / A mammoth tusk thaws out of the ground in Siberia.

    Ancient DNA has revolutionized how we understand human evolution, revealing how populations moved and interacted and introducing us to relatives like the Denisovans, a "ghost lineage" that we wouldn't realize existed if it weren't for discovering their DNA. But humans aren't the only ones who have left DNA behind in their bones, and the same analyses that worked for humans can work for any other group of species.

    Today, the mammoths take their turn in the spotlight, helped by what appears to be the oldest DNA ever sequenced. DNA from three ancient molars, one likely to be over a million years old, has revealed that there is a ghost lineage of mammoths that interbred with distant relatives to produce the North American mammoth population.

    Dating and the mammoth family tree

    Mammoths share something with humans: like us, they started as an African population but spread across much of the planet. Having spread out much earlier, mammoth populations spent enough time separated from each other to form different species. After branching off from elephants, the mammoths first split into what are called southern and steppe species. Later still, adaptations to ice age climates produced the woolly mammoth and its close relative, the North American mammoth, called the Columbian mammoth. All of those species, however, are extinct, and the only living relatives are the elephants.

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      Yukon gold miner unearths a mummified Ice Age wolf pup

      Kiona N. Smith · news.movim.eu / ArsTechnica · Tuesday, 22 December, 2020 - 12:15

    Color photo of wolf mummy puppy laying on a pillow

    Enlarge / The puppy's remains are dried out but mostly intact thanks to being buried in permafrost. (credit: Government of Yukon )

    This Ice Age wolf puppy doesn’t look much like a fearsome predator, what with her tiny puppy teeth and soft little ears. According to her DNA, however, the mummified puppy, named Zhùr, came from a population that's among the ancestors of all modern wolves. Canada’s permafrost freeze-dried her remains shortly after her death around 57,000 years ago.

    “She’s the most complete wolf mummy that’s ever been found. She’s basically 100 percent intact—all that’s missing are her eyes,” said Des Moines University paleontologist Julie Meachen.

    Puppy surprise

    In July 2016, miner Neil Loveless of Favron Enterprises was searching for gold in Alaska’s famed Klondike gold fields. He was water-blasting the frozen mud along the banks of Last Chance Creek. It’s a process called “hydraulic thawing,” meant to thaw and soften the frozen permafrost so miners can search for gold in the streambed deposits, an approach called placer mining. But Loveless found something far stranger and even more interesting than Klondike gold: a frozen, mummified wolf puppy.

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      Not-so-hostile takeover: Human Y chromosome displaced the Neanderthals’ version

      Kiona N. Smith · news.movim.eu / ArsTechnica · Thursday, 24 September, 2020 - 18:00 · 1 minute

    Comparison of Modern Human and Neanderthal skulls from the Cleveland Museum of Natural History.

    Comparison of Modern Human and Neanderthal skulls from the Cleveland Museum of Natural History. (credit: hairymuseummatt )

    We know that Neanderthals left their mark behind in the DNA of many modern humans, but that exchange worked both ways. The groups of Neanderthals our species met in Eurasia around 45,000 years ago already carried some Homo sapiens genes as souvenirs of much earlier encounters. A recent study suggests that those early encounters allowed the Homo sapiens version of the Y chromosome to completely replace the original Neanderthal one sometime between 370,000 and 100,000 years ago.

    Evolutionary geneticists Martin Petr, Janet Kelso, and their colleagues used a new method to sequence Y-chromosome DNA from two Denisovans and three Neanderthals from sites in France, Russia, and Spain (all three lived 38,000 to 53,000 years ago). The oldest Neanderthal genomes in Eurasia have Y chromosomes that look much more like those of Denisovans. Later Neanderthals, however, have Y chromosomes that look more like those of us humans.

    Gene flow is a two-way street

    Tens of thousands of years ago, our species shared the world with at least two other hominins. The tools, beads, and art they left behind hint that these other humans were probably a lot like us. And we were definitely all alike enough to have, apparently, a bit of sex.

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      Ancient DNA sheds light on Viking origins, travels

      Kiona N. Smith · news.movim.eu / ArsTechnica · Wednesday, 16 September, 2020 - 15:36 · 1 minute

    Modern reconstruction of a Viking longboat.

    Enlarge / Modern reconstruction of a Viking longboat. (credit: Dun.can / Flickr )

    A recent study of ancient DNA sheds light on who the Viking groups were and how they interacted with the people they met. The Viking Age, from around 750 to 1100 CE, left a cultural and economic impact that stretched from the coast of North America to the Central Asian steppe, and archaeology shows several examples of cultural exchange spanning continents. But to see patterns in how people swapped not only ideas, but genes, we need to look at the DNA of ancient people.

    “We know very well that the Viking Age changed the cultural and political map of Europe a thousand years ago, but we don't really know much about the demographic changes that accompanied these changes,” University of Copenhagen genomicist Ashot Margaryan told Ars. “This can be addressed based on population genetics methods.”

    Who were the Vikings?

    Today, we tend to think of the Vikings as one big mass of bearded raiders, swooping down European coasts, up rivers, and across the North Atlantic. But the Vikings themselves didn’t see themselves that way at all. The people who set sail to raid, trade, fish, and settle during the Viking Age saw themselves as members of distinct groups, with a shared culture but not a shared identity. The genetic evidence, it turns out, is on the Vikings’ side.

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