Fossil of extinct Denisovan human species identified on Tibetan Plateau, their diet revealed

Previous evidence had shown that Denisovans inhabited the plateau between 160,000 and 60,000 years ago. However, the new analysis identified one coastal specimen as Denisovan and dated it to a more recent period, 48,000 to 32,000 years ago.

The study, conducted by researchers from Chinese, Danish and British institutions, was published Wednesday in Nature.

Besides a hominid rib specimen, the other bones came from mammals that the Denisovans ate, and the study also found evidence that the Denisovans “processed” these bones for various purposes.

The researchers identified the Denisovan diet using a scientific method that differentiates bone collagen from different animals to determine which species the bones belong to. The researchers found that the bones came primarily from mammals, indicating that the Denisovan diet included these animals.

Most of the bones came from blue sheep (bharal), while others came from wild yaks, the extinct woolly rhinoceros, and the spotted hyena. Even fragments of snow leopard bone were found, as well as fragments of small mammals such as marmots and birds such as the golden eagle and the common pheasant.

Some of the bone fragments found showed signs of human activity, such as cut marks, indicating that the Denisovans had processed them. The meat had been removed and the bone marrow extracted, after which some of the bones had been used as materials for tool making, while traces of the preparation of animal skins had been discovered.

“Since we only know Denisovans from a few fossils worldwide, they remain a mystery. Each new individual we discover therefore adds an important piece to the puzzle of who they were, where they lived and when they lived,” Dr. Zandra Fagernäs of the University of Copenhagen, one of the study's authors, said in a statement from Lanzhou University in China.

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Humans and their cousins

Denisovans coexisted with modern humans and Neanderthals, our closest extinct relatives, for several thousand years in Eurasia. Denisovans were the smallest of the three related species, standing between 90 and 120 cm tall.

Homo sapiens Modern humans first appeared in Africa 300,000 years ago and encountered and interbred with the other two species after migrating to Asia and Europe about 70,000 years ago. Of the two oldest species, Neanderthals lived in Europe and western Asia 400,000 to 300,000 years ago, and Denisovans in Eurasia about 200,000 to 30,000 years ago.

Neanderthals are better known, with their first fossils having been discovered in a cave in Germany as early as 1856 AD. Denisovans, on the other hand, are a newly identified species.

The first Denisovan fossils identified as such were discovered in 2008 by Russian scientists in Denisova Cave, Siberia. These remains were classified as a new species in 2010 by Swedish geneticist Svante Pääbo, who won the Nobel Prize in Physiology in 2022.

Since then, Denisovan remains have been identified in Laos and the Tibetan cave. A jaw fragment from the Baishiya karst cave was established as a Denisovan in 2019.

The rib bone analyzed in the new study comes from another Denisovan individual, the researchers said in a statement from the University of Reading.

Although Denisovans are known to have coexisted with modern humans and Neanderthals before their extinction, researchers believe that only Denisovans lived in the Baishiya Karst Cave.

“Current evidence suggests that it was the Denisovans, and not any other human group, who occupied the cave and made efficient use of all the animal resources at their disposal throughout their occupation,” Dr Jian Wang of Lanzhou University said in the University of Reading statement.

Denisovans in Tibet

To identify the bone samples, the researchers used a screening method called Zooarchaeology by Mass Spectrometry (ZooMS). This method examined the amino acid structures of proteins and, combined with molecular analysis, was able to determine the species of most of the specimens.

Most of the bones come from blue sheep, a species common in the Himalayas even today. From the other bone fragments identified, the researchers concluded that the area around the cave was dominated by a grassy landscape with some small forested areas.

“The diversity of species identified partly answers questions about why Denisovans chose to live in the Baishiya karst cave and the surrounding Ganjia basin, and how they survived there for hundreds of thousands of years,” researcher Dr Dongju Zhang said in a statement from Lanzhou University.

The ZooMS analysis also revealed that the rib bone was a Denisovan fossil and dated it to between 48,000 and 32,000 years ago, which coincides with a time when modern humans were also dispersing across Eurasia.

(Edited by Nida Fatima Siddiqui)

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