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(CNN)A tooth unearthed from a remote cave in Laos is helping to sketch an unknown chapter in the human story.
Researchers believe the tooth belonged to a young female who lived at least 130,000 years ago and was likely a Denisovan -- an enigmatic group of early humans first identified in 2010.
The lower molar is the first fossil evidence placing Denisovans in Southeast Asia and may help untangle a puzzle that had long vexed experts in human evolution.
The only definitive Denisovan fossils have been found in North Asia -- in the eponymous Denisova cave in Siberia's Altai Mountains in Russia. Genetic evidence, however, has tied the archaic humans most closely to places much further south -- in what's now the Philippines, Papua New Guinea and Australia.
"This demonstrates that the Denisovans were likely present also in southern Asia. And it supports the results of geneticists who say that modern humans and the Denisovans might have met in Southeast Asia," said study author Clément Zanolli, a researcher in paleoanthropology at CNRS, the French National Center for Scientific Research and the University of Bordeaux.
Archaeologists uncovered the tooth in a place known as Cobra Cave, 160 miles (260 kilometers) north of Laos' capital, Vientiane, where excavations began in 2018. The study, which published in the journal Nature Communications on Tuesday, estimated the molar was between 131,000 and 164,000 years old, based on analysis of cave sediment, the dating of three animal bones found in the same layer, and the age of rock overlying the fossil.
"Teeth are like the black box of an individual. They preserve a lot of information on their life and biology. They have been always used by paleoanthropologists, you know, to describe species or to distinguish between species. So for us paleoanthropologists (teeth) are very useful fossils," Zanolli said.
Comparison with archaic human teeth
The researchers compared the ridges and dips on the tooth with other fossilized teeth belonging to archaic humans and found it didn't resemble teeth belonging to Homo sapiens or Homo erectus -- an archaic human that was the first to walk with an upright gait whose remains have been found across Asia. The cave find most closely resembled a tooth found in a Denisovan jawbone found on the Tibetan plateau in Xiahe county, in Gansu province, China. The authors said it was possible, though less likely, it could belong to a Neanderthal.