Denisovans were first identified in a Siberian cave; but their genes existed in several Asian and Oceanic groups, thus intriguing scientists
Representative photo from iStock The Denisovans, an extinct groups of archaic humans first discovered in a Siberian cave in 2008, were found outside of northern Asia too, the analysis of a tooth found in a Laos cave has shown.
The tooth, a permanent lower molar, was discovered by a team of scientists in December 2018 from Cobra Cave in Huà Pan province, Laos.
The scientists published their study A Middle Pleistocene Denisovan molar from the Annamite Chain of northern Laos May 17, 2022, in the journal Nature Communications.
They said the analysis of the tooth had shown that it belonged to a female individual of the genus Homo and was very probably that of a Denisovan.
“…considering the early maturational stage of the root, this tooth belonged to a juvenile individual corresponding to an age ranging from 3.5 to 8.5 years following modern developmental standards,” the authors wrote.
Denisovans had large dentition. The Laotian tooth’s morphology differentiated it from the smaller dentition of other human species such as Homo floresiensis, found on the island of Flores in Indonesia, Homo luzonensis found on the Philippines’ main northern island of Luzon as well as Homo sapiens, modern humans, the scientists said.
Instead, it showed a lot of similarity with a tooth that was discovered in a Denisovan jawbone found in Xiahe county, in China’s Gansu province.
“The close morphological affinities with the Xiahe specimen from China indicate that they belong to the same taxon and that Tam Ngu Hao 2 most likely represents a Denisovan,” the paper said.
However, the researchers did not discount the possibility that the tooth could belong to a Neanderthal, another group of archaic humans.
“The differences from Neanderthals that we observe do not preclude TNH2-1 from belonging to this taxon and would make it the south-eastern-most Neanderthal fossil ever discovered,” they wrote.
Mystery solved?
If the tooth is indeed of a Denisovan, it could be a missing piece of a puzzle that has intrigued those studying human evolution.
Denisovans were first identified in 2010 on the basis of a single finger bone found in the Denisova Cave in the Altai Mountains of Siberia in Russia in 2008.
However, Denisovan genes have been found in groups located on the opposite end of Asia.
“The geographic distribution of the Denisovans also remains debated. Modern Papuans, Aboriginal Australians, Oceanic/Melanesian, Philippine Ayta groups and, to a much lesser extent, mainland Southeast Asian populations, retain a Denisovan genetic legacy,” the paper noted.
The tooth found in Gansu had extended the southern range of the Denisovans to the Tibetan Plateau. But still, the groups in Southeast Asia and Oceania seemed far away.
Now, with the discovery of a Denisovan relic in Laos in Southeast Asia, it is possible to assume that Denisovans did inhabit this region.
“If TNH2-1 indeed belongs to a Denisovan, this occurrence, along with the recent discovery of a Denisovan mandible from the Tibetan Plateau, a high-altitude, hypoxic environment1, would suggest that this Pleistocene Asian population possessed a high degree of plasticity to adapt to very diverse environments,” the paper said.
The discovery also means that Southeast Asia was home to at least five human species from the genus Homo — Homo erectus, Denisovans/Neanderthals, Homo floresiensis, Homo luzonensis and Homo sapiens.
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