A nearly two-decade-old fossilized jawbone discovered off Taiwan’s coast has been identified as belonging to a male Denisovan, proving that these ancient humans once lived across an expansive area ranging from the icy expanses of Siberia to the tropical forests of the subtropics. Unlike their Neanderthal relatives, Denisovans have left behind scant physical evidence, making this find from Taiwan only the third confirmed site of Denisovan remains since their initial identification 15 years ago.

Despite the limited fossil record, genetic data indicates that Denisovans were widespread across East Asia for hundreds of thousands of years. Their existence was unknown until 2010 when a finger bone, later joined by other bone fragments and teeth from Denisova Cave in Southern Siberia, was confirmed to represent a previously unrecognized group on the hominin family tree. It wasn’t until 2010 that a jawbone with two molars, discovered by a Buddhist monk in a Tibetan cave in 1980, was connected to this mysterious lineage.

“It’s very sparse,” comments Frido Welker, a molecular anthropologist at the University of Copenhagen and co-author of the recent jawbone study published in Science. The Tibetan and Siberian fossils suggest Denisovans roamed Eurasia starting at least 200,000 years ago and managed to survive long enough to mingle genetically with modern humans, who emerged from Africa around 50,000 years ago. “Every piece that is informative changes our understanding,” Welker adds.

Support Quality Science Journalism

If you appreciate this article, please consider supporting our award-winning journalism by subscribing. Your subscription helps secure the future of in-depth reporting on the discoveries and ideas shaping our world.

The research indicates that Denisovans not only survived the harsh Siberian winters and the high altitudes of the Tibetan Plateau but also thrived in the warm, moist climates of lower-latitude East Asia. “Their adaptability was extraordinary,” states Bence Viola, a paleoanthropologist at the University of Toronto, not involved in the study. Unlike any other hominin group, including the resilient Neanderthals, Denisovans managed to inhabit a wide range of environments.

The jawbone, also known as Penghu 1, was retrieved from the shallow Penghu Channel off the western coast of Taiwan by a commercial fishing dredge before 2008 and was described in a study in Nature in 2015. Its DNA was too degraded to be identified, so Welker and his team turned to protein analysis, identifying two protein variants specific to Denisovans. “This was enough to confidently identify the fossil,” reports Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who was not involved in the study.

For experts in the field, the confirmation was not unexpected. “We all pretty much expected this would be a Denisovan,” Viola remarks, noting the robust structure similar to the Tibetan mandible. Additionally, in 2022, a molar resembling the Tibetan specimens was discovered in a cave in the Annamite Mountains in Laos. Although its DNA was also too degraded, the molar could potentially be tested using Welker’s protein analysis technique.

The jawbone further deepens a lingering mystery: comparisons of Denisovan DNA with that of modern humans show that Denisovan genes persist in billions of people today, from Aboriginal Australians to Native Americans. The highest concentrations of Denisovan DNA are found in modern populations in the Philippines, New Guinea, and other Pacific islands, making the geographic distribution of Denisovan fossils somewhat puzzling, as Siberia and Oceania are far apart.

This study provides another clue about where Denisovans and early modern humans might have interacted and exchanged genes, according to Emilia Huerta-Sánchez, a population geneticist at Brown University, who was not involved in the study. Her research indicates that several genetically distinct Denisovan populations interbred with humans, and some of the genes we inherited from them provided evolutionary benefits, such as helping Tibetans breathe in thin air.

However, the proteins in Penghu 1 provide limited insight into the gene flow between Denisovans and early modern humans, Huerta-Sánchez points out. “This is just a small piece of data,” she says, underscoring that obtaining a complete genome from a different geographic location would be more informative, albeit challenging due to DNA’s fragility, especially in warmer regions.

Welker plans to wait for more data before speculating on how these enigmatic relatives fit into the human evolutionary story. For now, he describes the jawbone as “a new addition to our hominin family”—another clue in the ongoing mystery of the Denisovans.