THE mystery of a robust ancient jawbone with large teeth and what species it belongs to has baffled scientists since it was dredged up in the 2000s.
But in a new study, scientists say the bone may belong to one of the most elusive of human ancestors – Denisovans.
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Paleoanthropologists have long debated whether the bone came from a Homo erectus, an archaic Homo sapiens, or a Denisovan.
The bone, known scientifically as Penghu 1, was netted by a fisherman from the floor of the Penghu Channel, about 15.5 miles off the west coast of Taiwan.
A technique that analyses the amino acids and proteins in bones found that the individual it belonged to was male, and most similar to Denisovans.
“The same technique can and is being used to study other hominin fossils to determine whether they too are Denisovans, Neanderthals or other hominin populations,” study co-author Frido Welker, a molecular anthropologist at the University of Copenhagen, told Live Science.
Denisovans are a long-extinct human relative who lived at the same time as Neanderthals and Homo sapiens.
The species roamed Asia, from the chilly corners of Siberia to humid areas like Taiwan, during the Pleistocene era – between 2.6 million to 11,700 years ago.
“It is now clear that two contrasting hominin groups – small-toothed Neanderthals with tall but gracile mandibles and large-toothed Denisovans with low but robust mandibles coexisted during the late Middle to early Late Pleistocene of Eurasia,” the researchers wrote in the study published in Science.
Denisovan fossils remain elusive, so the entire species is shrouded in mystery.
Unlike Neanderthals, whose bones have been found throughout Europe and western Asia for more than a century, Denisovans are mostly known from DNA.
Only a handful of fossils have ever been found, most of which come from Denisova Cave in Siberia.
Experts have struggled to identify new Denisovan skeletons without a large collection of fossils to compare to.
Little is known, therefore, about where Denisovans lived and how they are related to humans.
Animal bones found alongside the Penghu 1 suggest it may also be the youngest fragment of a Denisovan ever discovered – trumping the current title holder by 30,000 years.
Researchers were unable to use traditional methods such as carbon-14 or uranium dating on the bones because it was waterlogged for so long.
DNA extraction attempts also failed.
However, Welker explained that animal bones found with the jawbone suggest two age ranges – either 10,000 to 70,000 years ago or 130,000 to 190,000 years ago.
“If the specimen falls into the younger age range, it could potentially be the youngest Denisovan found to date,” he said.
Currently, the youngest Denisovan fossil, found on the Tibetan Plateau, is 40,000 years old.
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