Mystery Jawbone Pulled From the Sea Is a Rare Fossil From an Elusive Human Relative

The Denisovans were a mysterious radical of archaic humans who apt lived from astir 370,000 years agone to astatine slightest 30,000 years ago, and are believed to beryllium an offshoot oregon sister radical of the Neanderthals. What small we cognize astir Denisovans is based connected a fistful of fragmented fossil remains unearthed successful Siberia’s Denisova Cave and China’s Tibetan Plateau. A caller analysis, however, adds different portion to the Denisovan puzzle.

In a survey published contiguous successful the diary Science, a squad of researchers from Japan, Taiwan, and Denmark revealed that a jawbone antecedently discovered successful Taiwan belonged to a antheral Denisovan. They reached this decision aft conducting a paleoproteomic analysis—an investigation of past proteins—which revealed 2 macromolecule variants associated with Denisovans. The recognition provides the astir compelling grounds yet that Denisovans lived crossed antithetic habitats and adapted to divers climates.

“The high-quality palaeoproteomic information obtained from Penghu 1 [the fossilized jaw], enabled by comparatively bully fossil preservation and optimized macromolecule extraction methods, indicates that Penghu 1 belonged to a antheral Denisovan,” the researchers wrote successful the study.

An creator rendering of a Denisovan man. © Cheng-Han Sun.

Fishers dredged up Penghu 1, on with different carnal fossils, from the seabed of Taiwan’s Penghu Channel—an country that was portion of the Asian mainland during the little oversea levels of the Pleistocene Epoch (2.5 cardinal to 11,700 years ago). According to the study, the jawbone dates to either 10,000 to 70,000 years ago, oregon 130,000 to 190,000 years ago.

The crushed for 2 sets of reasonably divergent property ranges has to bash with the methods utilized to day the fossil. Because of the jawbone’s degradation, the squad couldn’t usage nonstop dating techniques similar uranium-series oregon radiocarbon dating. Instead, the scientists relied connected indirect clues, specified arsenic the fossil’s chemic composition, the types of carnal fossils recovered nearby, and humanities sea-level data. Altogether, this grounds pointed to the 2 imaginable clip windows.

The researchers, sequencing proteins extracted from the jawbone and teeth, recovered 4,241 amino acerb residues (the gathering blocks of protein) and identified 2 of them arsenic Denisovan-specific variants—meaning the jawbone belonged to a Denisovan. This nonstop molecular grounds of Denisovan beingness successful modern-day Taiwan supports a mentation antecedently indicated by familial studies of modern humans: namely, that Denisovans existed successful southeastern Asia.

One of the fewer things we cognize astir Denisovans is that they interbred with some Neanderthals and modern humans. As such, immoderate radical contiguous person genes passed down from distant Denisovan ancestors—particularly radical from southeastern Asia, suggesting that Denisovans lived and interbred with modern humans there. Before the jawbone’s paleoproteomic analysis, however, Denisovan fossils had lone ever been molecularly confirmed from bluish Asia.

“The recognition of Penghu 1 arsenic a Denisovan mandible confirms the inference from modern quality genomic studies that Denisovans were wide distributed successful eastbound Asia,” the researchers explained successful the study. What’s more, the “presence of Denisovans successful divers geographical and climatic zones,” ranging from the acold winters of the north, to the high-altitude chill of alpine subarctic zones, to the lukewarm and humid conditions of the tropical lowlands, “demonstrates their adaptational flexibility.”

The researchers besides conducted morphological analyses connected the jawbone, concluding that the Denisovan antheral had a robust jaw, ample molars, and notable basal structures. Significantly, these characteristics align with Denisovan fossils from the Tibetan Plateau, suggesting they whitethorn correspond broader Denisovan traits.

Ultimately, the survey sheds airy connected an past quality comparative we inactive cognize small about, portion expanding our knowing of aboriginal quality improvement crossed southeastern Asia.