Ancient jawbone came from mysterious group of human ancestors, scientists say

An ancient jawbone discovered in Taiwan belonged to an enigmatic group of early human ancestors called Denisovans, scientists reported Thursday.

Relatively little is known about Denisovans, an extinct group of human cousins that interacted with Neanderthals and our own species, Homo sapiens.

“Denisovan fossils are very scarce,” with only a few confirmed finds in East Asia, said study co-author Takumi Tsutaya at the Graduate University for Advanced Studies in Japan.

READ MORE: Fossils suggest ancestors of Indonesian ‘hobbits’ were even shorter

So far, the only known Denisovan fossils include partial jawbones, a few teeth and part of a finger bone found in caves in Siberia and Tibet. Some scientists believe fossils found in a cave in Laos may also belong to Denisovans.

The probable identification of the jawbone from Taiwan as Denisovan expands the region where scientists know these ancient people once lived, said Tsutaya.

The partial jawbone was first recovered when a fishing operation dredged the seafloor in the Penghu Channel near the Taiwan Strait. After it was sold to an antique shop, a collector spotted it and purchased it in 2008, then later donated it to Taiwan’s National Museum of Natural Science.

The Penghu Islands coast at low tide, located off the coast of Taiwan. Although the exact location is unknown, the fossilized mandible of a male Denisovan, an extinct archaic human, was discovered off the coast of this island. Photo by Takumi Tsutaya/ Handout via Reuters

Based on the composition of marine invertebrates found attached to it, the fossil was dated to the Pleistocene era. But exactly which species of early human ancestor it belonged to remained a mystery.

The condition of the fossil made it impossible to study ancient DNA. But recently, scientists in Taiwan, Japan and Denmark were able to extract some protein sequences from the incomplete jawbone.

READ MORE: Ancient stone tools found in Ukraine may have been used by early humans over 1 million years ago

An analysis showed some protein sequences resembled those contained in the genome of a Denisovan fossil recovered in Siberia. The findings were published in the journal Science.

An illustration of a robust male Denisovan, an extinct archaic human, walking under the bright sun of Taiwan. Illustration by Cheng-Han Sun/Handout via Reuters

While the new research is promising, Rick Potts, director of the Smithsonian Institution’s Human Origins Project, said he would like to see further data before confirming the Taiwan fossil as Denisovan.

Potts, who was not involved in the new research, praised the study for “a fantastic job of recovering some proteins.” But he added, such a small sliver of material may not give a full picture.

READ MORE: Early humans used fire to permanently change the landscape

At one time, at least three human ancestor groups — Denisovans, Neanderthals and Homo sapiens — coexisted in Eurasia and sometimes interbred, researchers say.

“We can identity Neanderthal elements and Denisovan elements” in the DNA of some people alive today, said Tsutaya.