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Thread: Denisovan jawbone found on Tibetin Plateau

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    Denisovan jawbone found on Tibetin Plateau

    exciting news!

    https://gizmodo.com/jawbone-fossil-r...mys-1834444888

    "Jawbone Fossil Reveals More About the Denisovans, a Mysterious Species that Mated With Modern Humans

    George Dvorsky
    26 minutes agoFiled to: DENISOVANS

    A photo of the Xiahe mandible.


    In 2010, archaeologists found evidence of a previously unknown hominin, the Denisovans, in a Siberian cave. Researchers are now reporting the discovery of a 160,000-year-old Denisovan jawbone pulled from a cave on the Tibetan Plateau. The fossil is now the first evidence of this mysterious human species outside of Siberia, and the earliest evidence of a hominin presence in this part of the world.

    This Denisovan mandible was discovered nearly 40 years ago by a monk who was wandering through Baishiya Karst Cave in Xiahe, China. The cave is located on the Tibetan Plateau, which over 1,240 miles (2,000 kilometers) from Denisova cave in Siberia—the only other place in the world where Denisovan fossils have been unearthed. The details of this discovery were published today in Nature.

    We suspected this day would come, and it’s finally happened—the first fossil evidence of this species outside of Denisova cave, which is located in the Siberian Altai Mountains. Archaeologists have only known about the Denisovans—a hominin species closely related to the Neanderthals and not a direct ancestor of modern humans—for the past nine years. Scientists were able to extract DNA fragments from a single Denisovan finger bone found in Denisova cave, allowing them to identify the previously undiscovered species. Today, bits of Denisovan DNA linger on in present day Asian, Australian, and Melanesian populations. This fact alone suggested Denisovans interbred with modern humans (probably around 50,000 to 40,000 years ago), and that they were geographically dispersed. Given all this, the dearth of Denisovan fossils outside of Siberia was somewhat of an enigma.

    Like the Neanderthals, the Denisovans eventually went extinct—save for the bits of DNA we inherited from them. Indeed, a remarkable and puzzling aspect of Denisovan DNA is the presence of an allele known as EPAS1. This genetic mutation confers resistance to hypoxia, otherwise known as altitude sickness. Archaeologists couldn’t understand why hominins living in a Siberian cave a mere 2,300 feet (700 meters) above sea level needed a resistance to a high altitude, low-oxygen environment. The discovery of a Denisovan fossil on the Tibetan Plateau, 10,760 feet (3,280 meters) above sea level, seems to solve this mystery. Fascinatingly, the EPAS1 allele lives on in the genome of present-day Himalayans—a trait that likely originated from the Denisovans.

    “One of the most spectacular aspects of this new discovery is its location on the Tibetan Plateau,” Jean-Jacques Hublin, the lead author of the new paper and an archaeologist from the Max Planck Institute for Evolutionary Anthropology (MPI-EA), said at a press conference on Monday. “Nobody imagined that archaic humans lived there—we thought only by modern humans like us.”


    The discovery, he said, is offering new insights into the Denisovan genome and the special gene variant that protects against hypoxia.

    “Now we have an explanation for that,” he said. “The Denisovan population, or populations related to them, lived in high-altitude environments for a very long time, and later passed on this gene to modern populations.”

    The Xiahe Denisovans lived during a particularly cold period on the Tibetan Plateau, explained Hublin. Some 160,000 years ago, during the late Middle Pleistocene, the Denisovans had to deal with a “more challenging environment” than the one experienced in the region today—an observation that “blows my mind,” said Hublin.

    As noted, this well-preserved mandible, of which only the right half remains, was discovered in 1980 by a monk, but it eventually made its way to Lanzhou University. Since 2010, Lanzhou researchers Fahu Chen and Dongju Zhang, both co-authors of the new study, have been studying the area in which the jawbone was found. The MPI-EA researchers joined the investigation in 2016.


    A physical analysis of the jawbone and its teeth distinguished the fossil as belonging to a Denisovan individual. Unfortunately, however, no DNA could be extracted from the mandible, but MPI anthropologist and study co-author Frido Welker conducted a cutting-edge protein analysis to further discern the provenance of the fossil. By extracting and analyzing proteins from the molars, Welker was able to identify protein sequences which, like fingerprints, are unique to Denisovans. These coding sequences were then compared to those produced by Neanderthals and modern humans. The “preserved coding sequences were most similar to Denisovans compared to anything else,” Welker said during Monday’s press conference. “We concluded that the mandible belongs to Denisovans.”

    A heavy carbonate crust was attached to the mandible, allowing the archaeologists to date the fossil. Erring on the side of caution, the researchers dated the jawbone to 160,000 years ago, but said it could be older.


    As for the mandible itself, it contained some ancient features, including very large molars. One of the molars hadn’t yet pierced through the gums, which means it likely belonged to an adolescent Denisovan individual. At the press conference, Hublin said its most distinguishing characteristic was the “robust teeth,” but he admitted “we still know very little of what they looked like.” When pressed to make an educated guess, Hublin said Denisovans “probably looked like an early form of Neanderthals.”

    In terms of major takeaways, the new discovery offers at least three. First, we finally have an explanation for why Denisovans had a gene variant to stave off hypoxia. Second, this jawbone is evidence that Denisovans “were connected with other populations of Denisovans,” said Hublin, referencing to the Altai Denisovans in Siberia. And finally, we now know that Denisovans were, as a whole, geographically dispersed.

    “Naturally, one wishes that DNA was present in that specimen,” Katerina Douka, an archaeologist at the University of Oxford who’s not affiliated with the new study, wrote in an email to Gizmodo. “Without it, other possibilities cannot be ruled out completely, but I agree that with the currently available data Denisovan is the most likely attribution.”

    Chris Stringer, a paleoanthropologist at the Natural History Museum in London—also not involved in the new study—described this “first use” of ancient protein analysis to identify the Denisovan fossil as a “notable landmark.”

    “Of course it is early days for this research, and we must remain slightly cautious while both the data from the fossil and from the comparative samples are sparse, but the technique shows great promise for mapping the relationships of fossil hominins where ancient DNA is not preserved,” explained Stringer in an email to Gizmodo.

    For Douka, the most exciting aspect of the discovery was not the presence of Denisovans outside of Siberia (which she said she suspected all along), but the location of the new site at over 3,000 meters above sea level. The presence of Denisovans at this altitude during this particular geological period “is truly astonishing,” she said, and a discovery that jibes well with her own research from earlier this year. In that study, Douka’s team dated the oldest Denisovan fossils found in Denisova cave to the same time period indicated by the Tibetan Plateau fossil. This happened during a “weak interglacial period which would have allowed humans,” a group that included Denisovans, Neanderthals, and possibly anatomically modern humans, “to disperse widely, even in uninviting parts of Asia, followed by the penultimate Ice Age, which saw a return to colder conditions and the rather surprising presence of Denisovans in Siberia and, as we know now, the Tibetan plateau,” said Douka.

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    O this is great in so many aspects! Recently a similar technique like this was used to establish ancestry of a woolly Rhinoceros from Dmanisi cave which was 1.77 million year old. This means that we have a second way to determine ancestry, next to ancient DNA and one that allows us to look far deeper in time. This will allow for determine ancestry from samples which are too old for DNA recovery (Homo Erectus) and samples which yielded no usable DNA (Red Deer Cave, Flores man).

    https://anthrogenica.com/showthread....l=1#post484171

    EDIT: Also, this will greatly extend the knowledge of the Denisovan molar morphology. See for example this: https://www.academia.edu/32406136/Th...ve_In_English_
    Last edited by epoch; 05-02-2019 at 08:18 AM.

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    Quote Originally Posted by epoch View Post
    This means that we have a second way to determine ancestry,
    Proteins were used BEFORE we had DNA.
    They are nothing new.
    Just overlooked while we had something better.

    In the early 1970s when DNA techniques were expensive and tricky, this then undergraduate was given a protein experiment to demonstrate some principles that also applied to DNA. One lesson that has stayed with me ever since.

    The tricky thing with these ancient samples is to avoid contamination and to ensure that any proteins analysed are from the sample itself.
    Last edited by Saetro; 05-02-2019 at 07:17 PM.

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    The paper has some PCA's with morphological and dental geometrics of the mandible and teeth. It turns out that it maps pretty well with some Heidelberg (Mauer) samples and samples from Arago cave. That is pretty interesting as the proto-Neanderthals from Sima de los Huesos had mtDNA types that were closer to Denisovans than to later Neanderthals.
    Last edited by epoch; 05-04-2019 at 08:43 PM.

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    "One of the most the most remarkable things about the new discovery of a Denisovan Jawbone is where it appears morphologically on a PCA. Is Homo Erectus simply an early Denisovan?"
    https://twitter.com/vagheesh/status/1123640550408716289



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    Well 1 Denisovan on a graph of 100+ modern humans, dozens of Neanderthals, and a handful of Erectus, where would it be expected to plot?
    I'd assume due to their 1+ million years of existence and wide range of habitat, Erectus would have the most diversity.
    Neanderthals being more confined in space and time, and bottlenecked genetically, would probably share a suite of derived features. Same thing goes for modern humans to some extent.
    So if Denisovan aren't derived for Neanderthal or modern features, they'd probably just get dumped within Erectus until there's enough Densiovan samples for them to form their own cluster, right?
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    Quote Originally Posted by Kale View Post
    Well 1 Denisovan on a graph of 100+ modern humans, dozens of Neanderthals, and a handful of Erectus, where would it be expected to plot?
    I'd assume due to their 1+ million years of existence and wide range of habitat, Erectus would have the most diversity.
    Neanderthals being more confined in space and time, and bottlenecked genetically, would probably share a suite of derived features. Same thing goes for modern humans to some extent.
    So if Denisovan aren't derived for Neanderthal or modern features, they'd probably just get dumped within Erectus until there's enough Densiovan samples for them to form their own cluster, right?
    Yes possible.
    There is also the possibility that many of the remains presently classified as Erectus are actually Denisovans.

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