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可能發現新人種 -- Sam Elliott-Gibbs
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Mystery as ancient skull found without a chin 'could be from new species of human'
Scientists have spent the past four years examining the fossilised remains dug up in Hualongdong (華龍洞), China, and the skull belonging to a child could turn out to be an incredible find
Sam Elliott-Gibbs, 08/09/23
The find in Hualongdong, China, has left experts baffled (Image: Wu et al., Journal of Human Evolution, 2023；請至原網頁參看圖片)
Archaeologists may have identified a new species of human after a chinless skull from hundreds of thousands of years ago was discovered in Asia.
Scientists have been examining the fossilised remains since they were dug up in Hualongdong, China, nearly four years ago. It included a jaw and leg bones and a skull that belongs to a child, but mystery still surrounds the find. The remains were likely to belong to a 12 or 13-year-old.
But its features did not 'match the lineage which split to form Neanderthals, nor Denisovans' and it has left the experts baffled. They said the the species 'did not possess a true chin' as they continue to search for answers. The study was published in the Journal of Human Evolution, hinting at an entirely new lineage, a hybrid between modern humans and those from the Denisovans region.
Homo sapiens only appeared about 120,000 years ago in China. Now it has been suggested that this may be the last common ancestor of Homo sapiens and Neanderthals, which arose in southwest Asia before spreading to all sides of the world.
Scientists may have identified a new species ( Image: Wu et al., Journal of Human Evolution, 2023；請至原網頁參看圖片)
The paper read: "Excavations in Hualongdong, East China, have yielded abundant hominin fossils dated to 300 ka. There is a nearly complete mandible that fits well with a partial cranium, and together they compose the skull labeled as HLD 6.
"Thus far, detailed morphological description and comparisons of the mandible have not been conducted. Here we present a comprehensive morphological, metric, and geometric morphometric assessment of this mandible and compare it with both adult and immature specimens of Pleistocene hominins and recent modern humans.
"Results indicate that the HLD 6 mandible exhibits a mosaic morphological pattern characterized by a robust corpus and relatively gracile symphysis and ramus. The moderately developed mental trigone and a clear anterior mandibular incurvation of the HLD 6 mandible are reminiscent of Late Pleistocene hominin and recent modern human morphology.
The skull and bones were likely to belong to a 12 or 13-year-old child (Image: Wu et al., Journal of Human Evolution, 2023；請至原網頁參看圖片)
"However, the weak expression of all these features indicates that this mandible does not possess a true chin. Moreover, a suite of archaic features that resemble those of Middle Pleistocene hominins includes pronounced alveolar planum, superior transverse torus, thick corpus, a pronounced endocondyloid crest, and a well-developed medial pterygoid tubercle.
"The geometric morphometric analysis further confirms the mosaic pattern of the HLD 6 mandible. The combination of both archaic and modern human features identified in the HLD 6 mandible is unexpected, given its late Middle Pleistocene age and differs from approximately contemporaneous Homo members such as Xujiayao (許家窯)."
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A new human species? Mystery surrounds 300,000-year-old fossil
A chinless jawbone from eastern China that displays both modern and archaic features could represent a new branch of the human family tree.
Dyani Lewis, 09/18/23
A fossilized jawbone discovered in a cave in eastern China bears a curious mix of ancient and modern features, according to a detailed analysis that compares it with dozens of other human specimens. The finding, published in the Journal of Human Evolution, indicates that the 300,000-year-old bone could have belonged to an as-yet undescribed species of archaic human1.
Scientists excavating a cave called Hualongdong, located in Anhui province in eastern China, have unearthed remains of 16 individuals that date to around 300,000 years ago 2. Several fragments belong to the skull of a 12-to-13-year-old juvenile.
Xiujie Wu, a palaeoanthropologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, and her colleagues first described the skull in 2019 2. But in 2020, while sifting through trays of animal bones found in the cave, they identified a fragment of a mandible — the lower part of the jaw — that could be another piece of the same skull.
The discovery has enabled a more detailed analysis of where the Hualongdong people fit on the human family tree. The mandible has a mixture of both modern and archaic features. For example, the bone along the jawline is thick, a feature shared with early human species, such as Homo erectus. It also lacks a true chin, the presence of which is a key feature of Homo sapiens. But the side of the mandible that attaches to the upper jaw is thinner than those of archaic hominins and more reminiscent of that of modern humans.
Ancient and modern
The analysis deepens the mystery of which ancient human species inhabited the region during the Middle to Late Pleistocene epoch, a period spanning almost 800,000 years that preceded the end of the last Ice Age, around 12,000 years ago.
A digital comparison of the newly uncovered mandible with 83 other jawbones confirmed a strange mix of ancient and modern anatomical features. Wu and her colleagues used juvenile and adult bones from Neanderthals (Homo neanderthalensis), which lived in Eurasia until 40,000 years ago, H. sapiens from around the world, and H. erectus, a species whose range extended from eastern Africa to the southeast Asian islands of Indonesia between 1.9 million and 250,000 years ago.
Wu says that the H. sapiens-like features of the jawbone set it apart from those of other hominins from the Middle Pleistocene, including those of a 160,000-year-old Denisovan from Tibet 3 and of the around 770,000-year-old remains known as Peking Man 4. She adds that the Hualongdong people could represent a previously unknown ancestor or close relative of early H. sapiens.
But the notion that modern humans arose from ancestors in Asia is not widely accepted. The oldest H. sapiens fossils, which date to 230,000 years ago, are from sites in Ethiopia 5.
Confusing picture
The picture of human occupation in East Asia during the Pleistocene is a confusing one, says Yameng Zhang, a palaeoanthropologist at Shandong University in Jinan, China. He says that numerous species of archaic hominin inhabited East Asia during the Middle Pleistocene, a period from around 800,000 to 126,000 years ago. It is unclear whether any of these could be ancestors of modern humans — like Neanderthals and Denisovans, they might simply have died out.
The combination of ancient and modern features in the Hualongdong mandible is similar to those of remains found during the early 2000s at the Jebel Irhoud archaeological site in Morocco, says María Martinón-Torres, a palaeoanthropologist at the National Research Center on Human Evolution in Burgos, Spain, who was part of the team that described the findings at Hualongdong. The Jebel Irhoud remains — which include several skull fragments and a nearly complete mandible — have an age similar to that of the Hualongdong ones and are thought to belong to one of the earliest members of the evolutionary lineage that includes H. sapiens 6、7. “More fossils and studies are necessary to understand [the Hualongdong people’s] precise position in the human family tree,” she says.
Martinón-Torres adds that ancient proteins extracted from the bones could shed further light on how the Hualongdong people are related to modern humans, as well as to more-archaic species.
doi: https://doi.org/10.1038/d41586-023-02924-8
References
1. Wu, X. et al. J. Hum. Evol. 182, 103411 (2023). Article PubMed Google Scholar
2. Wu, X.-J. et al. Proc. Natl Acad. Sci. USA 116, 9820–9824 (2019). Article PubMed Google Scholar
3. Chen, F. et al. Nature 569, 409–412 (2019). Article PubMed Google Scholar
4. Shen, G., Gao, X., Gao, B. & Granger, D. E. Nature 458, 198–200 (2009). Article PubMed Google Scholar
5. Vidal, C. M. et al. Nature 601, 579–583 (2022). Article PubMed Google Scholar
6. Hublin, J.-J. et al. Nature 546, 289–292 (2017). Article PubMed Google Scholar
7. Richter, D. et al. Nature 546, 293–296 (2017). Article PubMed Google Scholar
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