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A recent study published in Science reveals that a fossilized jawbone, discovered by fishermen off the coast of Taiwan, belongs to the Denisovans, an enigmatic group of ancient hominins. This finding significantly expands the geographical distribution of Denisovans beyond previously known locations.
The fossil, called Penghu 1, was acquired in 2008 by a Taiwanese man, who later donated it to the National Museum of Natural Science in Taiwan. Initially classified as an unknown species of Homo, subsequent analysis confirmed its identity as a Denisovan. The fossil is a right lower jaw containing four cheek teeth and a partial canine, which allowed researchers to conduct an in-depth examination.
Biological anthropologist Takumi Tsutaya and his team provided two compelling pieces of evidence pointing to the jaw’s Denisovan origins. Initially, they analyzed 4,241 protein residues from the fossil and identified two that displayed a chemical structure commonly found in Denisovans. Notably, these alterations were absent in Neandertals and rare in contemporary humans. While no DNA could be extracted from Penghu 1, the protein mutations suggest a strong link to Denisovans, with one protein marker indicating male sex originating from the jaw’s enamel.
Tsutaya highlighted the significance of this discovery, emphasizing that the ability to analyze protein variation from a fossil retrieved from the ocean represents substantial progress in paleogenomics. The second line of evidence stems from the anatomical similarities between Penghu 1 and other Denisovan fossils, particularly a jawbone found on the Tibetan Plateau, which shares characteristics like thick bones and large molars.
Attempts to date Penghu 1 directly have been hindered due to seawater exposure and degradation of bone collagen. However, researchers speculate it may date back either to the period of glacial formation around 70,000 to 10,000 years ago or from approximately 190,000 to 130,000 years ago, when Taiwan was connected to mainland Asia via lowered sea levels.
The implications of this find suggest that Dennisovans thrived in a wider array of environments than previously assumed, adapting not only to the harsh conditions of Siberia and Tibet but possibly also to the milder climates of Taiwan, located about 4,000 kilometers from Denisova Cave.
Paleoanthropologist Yousuke Kaifu from the University of Tokyo speculates that Denisovans might have inhabited a large area encompassing Central and East Asia, likely exhibiting regional variations that have yet to be fully understood. Meanwhile, some researchers, like Xiujie Wu from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, propose classifying Penghu 1 and other Denisovan fossils as belonging to a separate species, Homo juluensis. This proposition is supported by other finds from China, which suggest distinctly large braincases dating back between 200,000 and 105,000 years.
However, some experts urge caution. Athreya argues that the limited and often fragmentary nature of known Denisovan fossils prevents definitive conclusions about their morphology. As she notes, a complete understanding of who the Denisovans were is essential for uncovering their relationship with modern humans and their ultimate fate.
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