This unusual tooth is the first fossil evidence of Denisovans in Southeast Asia

A child living in the village of Long Gua Pa in northeastern Laos approached a team of archaeologists in order to show them a cave full of bones. The team began to chisel into the cave's cementlike walls, exposing the remains of ancient rhinoceroses, tapirs, pigs, rodents, and a single humanlike molar. The tooth was found to be that of a Denisovan, a mysterious cousin of Neanderthals and modern humans who died out about 30,000 years ago. The first fossil evidence of Denisovans in Southeast Asia supports clues in the genetics of modern Indigenous populations.

We assumed that Denisovans were in Southeast Asia, but we didn't have the fossils for it.

Neanderthals and Denisovans were both present in the same area hundreds of thousands of years ago. fossil evidence of their existence has been hard to come by, most notably in one group of Indigenous Filipinos who inherit about 5% of their genome from Denisovans. There are a few teeth, a finger bone, and a piece of skull that have been uncovered by researchers. No fossils have turned up in Southeast Asia despite the genetic clues that Denisovans was there.

The archaeologists who were led to the cave had been excavating early modern human sites in the Annamite Mountains for 15 years. The rocky accretions around the tooth were dissolved in the depths of Cobra Cave. It was pegged as a permanent lower hominin molar by the researchers. Which species?

Laura Shackelford, a paleoanthropologist at the University of Illinois, said that it looked kind of human, but not quite right for a modern human. It was bigger and had a different thickness. The pattern of ridges and hills didn't match that of modern humans.

The study's co-author, a paleoanthropologist at the University of Bordeaux and a dental structure expert, helped eliminate a few other possibilities. There is no evidence that Neanderthals ever lived in Southeast Asia.

The tooth was scanned using an x-ray scanner at the Max Planck Institute for Evolutionary Anthropology. Next, they compared the teeth of humans and apes. They found that it was very similar to the lower molars on the Denisovan mandible.

The team used a variety of techniques to date the stalagmite and stalactites in the cave, and found that it was 130,000 to 160,000 years old.

The tooth's extreme age and the region's hot, tropical climate made it unlikely to be saved. The researchers took small chips of tooth enamel and analyzed them for ancient proteins, which are hardier than DNA, but offer less precise answers about ancestry and other characteristics. The owner of the Lao molar was most likely a female, as the makeup of its proteins confirmed. The tooth had no wear and was in completely formed root, suggesting that it was a juvenile when she died.

The tooth is Denisovan, according to a dental paleoanthropologist at New York University. She hopes other examples of Denisovan teeth will show up in the collections of universities and museums. That is pretty amazing.