A molar found in a cave in Laos may belong to a member of the Denisovans, a group of ancient humans first identified in 2010. If confirmed, it would be the first fossil evidence of the Denisovans in Southeast Asia and would join just a handful of other remains unearthed from these hominins that lived about 500,000 to 30,000 years ago, writes Nature’s Freda Kreier. The researchers published their findings in the journal Nature Communications.
Previous research has placed the Denisovans in Siberia and Tibet, but their DNA has been found in present-day humans much farther south, in Australia and the Philippines, suggesting the Denisovans and Homo sapiens had interbred.
“We knew that Denisovans should be here,” Laura Shackelford, a paleoanthropologist at the University of Illinois at Urbana-Champaign and a co-author of the new study, tells the New York Times’ Carl Zimmer. “It’s nice to have some tangible evidence of their existence in this area.”
The authors estimate the tooth is between 131,000 and 164,000 years old and belonged to a female who died between the ages of 3.5 and 8.5. In the study, the researchers compared the molar to those of other ancient humans, and found that it didn’t quite resemble teeth belonging to species such as Homo sapiens or Homo erectus. Instead, it matched most closely with a molar from a Denisovan jawbone discovered in Tibet.
“Everything fits with what we would expect for a Denisovan lower molar,” Bence Viola, a paleoanthropologist at Canada’s University of Toronto who wasn’t involved with the study, tells National Geographic’s Maya Wei-Haas and Michael Greshko. “Denisovans have absolutely gigantic teeth,” she tells Nature. “So it seems like a good assumption that this is likely a Denisovan.”
But some researchers are more skeptical, especially because the authors haven’t yet done a DNA analysis on the tooth, and the tropical climate in which it was found makes this process more difficult, per CNN.
"There is a chain of assumptions the authors accept in order to confirm that this is a Denisovan fossil," Katerina Douka, an assistant professor of archaeological science at the department of evolutionary anthropology at the University of Vienna, tells CNN’s Katie Hunt. "The reality is that we cannot know whether this single and badly preserved molar belonged indeed to a Denisovan, a hybrid or even an unknown hominin group. It might well be a Denisovan, and I would love it to be a Denisovan, because how cool would that be? But more confident evidence is needed.”
It’s possible the tooth could have come from a Neanderthal or an individual with mixed Denisovan and Neanderthal ancestry, co-lead author Fabrice Demeter of the University of Copenhagen tells Science News’ Bruce Bower. The authors plan to continue searching the cave in Laos for more fossils and hope to extract DNA from the molar to confirm its owner.
“When we started looking in Laos, everyone thought we were crazy,” Shackelford tells Nature. “But if we can find things like this tooth—which we weren’t even anticipating—then there are probably more hominin fossils to be found.”