The Denisovans were a mysterious group of archaic humans who likely lived from around 370,000 years ago to at least 30,000 years ago, and are believed to be an offshoot or sister group of the Neanderthals. What little we know about Denisovans is based on a handful of fragmented fossil remains unearthed in Siberia’s Denisova Cave and China’s Tibetan Plateau. A new analysis, however, adds another piece to the Denisovan puzzle.
In a study published today in the journal Science, a team of researchers from Japan, Taiwan, and Denmark revealed that a jawbone previously discovered in Taiwan belonged to a male Denisovan. They reached this conclusion after conducting a paleoproteomic analysis—an analysis of ancient proteins—which revealed two protein variants associated with Denisovans. The identification provides the most compelling evidence yet that Denisovans lived across different habitats and adapted to diverse climates.
“The high-quality palaeoproteomic data obtained from Penghu 1 [the fossilized jaw], enabled by relatively good fossil preservation and optimized protein extraction methods, indicates that Penghu 1 belonged to a male Denisovan,” the researchers wrote in the study.
Fishers dredged up Penghu 1, along with other animal fossils, from the seabed of Taiwan’s Penghu Channel—an area that was part of the Asian mainland during the lower sea levels of the Pleistocene Epoch (2.5 million to 11,700 years ago). According to the study, the jawbone dates to either 10,000 to 70,000 years ago, or 130,000 to 190,000 years ago.
The reason for two sets of fairly divergent age ranges has to do with the methods used to date the fossil. Because of the jawbone’s degradation, the team couldn’t use direct dating techniques like uranium-series or radiocarbon dating. Instead, the scientists relied on indirect clues, such as the fossil’s chemical composition, the types of animal fossils found nearby, and historical sea-level data. Altogether, this evidence pointed to the two possible time windows.
The researchers, sequencing proteins extracted from the jawbone and teeth, recovered 4,241 amino acid residues (the building blocks of protein) and identified two of them as Denisovan-specific variants—meaning the jawbone belonged to a Denisovan. This direct molecular evidence of Denisovan presence in modern-day Taiwan supports a theory previously indicated by genetic studies of modern humans: namely, that Denisovans existed in southeastern Asia.
One of the few things we know about Denisovans is that they interbred with both Neanderthals and modern humans. As such, some people today have genes passed down from distant Denisovan ancestors—particularly people from southeastern Asia, suggesting that Denisovans lived and interbred with modern humans there. Before the jawbone’s paleoproteomic analysis, however, Denisovan fossils had only ever been molecularly confirmed from northern Asia.
“The identification of Penghu 1 as a Denisovan mandible confirms the inference from modern human genomic studies that Denisovans were widely distributed in eastern Asia,” the researchers explained in the study. What’s more, the “presence of Denisovans in diverse geographical and climatic zones,” ranging from the cold winters of the north, to the high-altitude chill of alpine subarctic zones, to the warm and humid conditions of the tropical lowlands, “demonstrates their adaptational flexibility.”
The researchers also conducted morphological analyses on the jawbone, concluding that the Denisovan man had a robust jaw, large molars, and notable root structures. Significantly, these characteristics align with Denisovan fossils from the Tibetan Plateau, suggesting they may represent broader Denisovan traits.
Ultimately, the study sheds light on an ancient human relative we still know little about, while expanding our understanding of early human development across southeastern Asia.
