Taiwan’s Jawbone Reveals Insights on Ancient Human Migration

Recent molecular analysis has confirmed that a jawbone found offshore from Taiwan belonged to a Denisovan, highlighting how this mysterious group of archaic humans occupied a diverse range of climates across eastern Eurasia, from icy and dry to warm and damp.

While scientists could not extract any DNA from this fossil, which includes part of the lower jaw with five attached teeth, they did identify two protein variants unique to Denisovans, differentiating them from Neanderthals and Homo sapiens based on earlier fossil studies.

Proteins related to the Y-chromosome were found in the fossil’s dental enamel, indicating that the individual was male.

Establishing the age of the fossil has been challenging, as researchers could not apply standard dating techniques. They estimate it to be anywhere from 10,000 to 70,000 years old, or 130,000 to 190,000 years old, based on associated animal fossils discovered alongside it.

This places it in contention for the title of the youngest-known Denisovan fossil.

The jawbone, along with various animal remains, was retrieved from the ocean floor through dredging during commercial fishing in the Penghu Channel, an area that was once dry land. It eventually ended up in an antique shop in Taiwan, where it was purchased in 2008 and later donated to a local museum.

Denisovans were previously unknown until their remains were found in Denisova Cave in Siberia in 2010. Genetic analysis revealed that they are a close relative to Neanderthals, the robust archaic humans that lived in areas of Eurasia.

Both groups interacted significantly with Homo sapiens, including instances of interbreeding, before ultimately disappearing, though the causes of their extinction remain unclear.

Genetic analyses suggest that Denisovans diverged from Neanderthals approximately 400,000 years ago, but the timing of their extinction is still uncertain.

Currently, Denisovans are known only from fragments of bones and teeth, with no nearly complete skeletons found yet. Consequently, the discovery of any new fossils is invaluable for understanding their physical characteristics and habitat.

“From our findings, we can only hypothesize about the shape of their jawbone and teeth, but at least we know that the mandibles of male Denisovans were quite robust, and their cheek teeth were larger compared to those of Neanderthals and modern humans,” explained Takumi Tsutaya, a biological anthropologist from the Graduate University for Advanced Studies, SOKENDAI, in Japan, who led the study published in the journal Science.

Confirmed Denisovan fossils have now been found in three locations: the remains from the Penghu Channel, teeth and a small finger bone from Denisova Cave in Russia, and a mandible and rib fragment from Baishiya Karst Cave on the Tibetan Plateau in China’s Gansu province. A molar from Cobra Cave in Laos is also believed to be Denisovan based on its morphology.

This evidence suggests that Denisovans roamed a broad area of Eurasia—approximately 2,800 miles (4,500 km) from Denisova Cave to the Penghu Channel—and adapted to a variety of environments, from the cold mountains of Siberia to the high Tibetan Plateau, as well as the warmer climates of Laos and the subtropical coast of Taiwan.

“Thus, Denisovans must have had the ability to adapt to a wide array of habitat types,” noted molecular anthropologist Frido Welker of the University of Copenhagen, a co-author of the study.

The most recently dated Denisovan fossil is a rib fragment from Baishiya Karst Cave, estimated to be about 40,000 years old, which coincides with the date of the youngest-known Neanderthal remains. Modern humans migrated out of Africa and into regions inhabited by Neanderthals and Denisovans, shortly after which both groups became extinct.

“Our knowledge of Denisovans is still limited, which makes it hard to determine the reasons for their extinction,” Welker commented. “However, a lasting impact remains, as some populations in East and Southeast Asia carry Denisovan ancestry in their genetic makeup today.”