Creighton professor and research team unearth story of ancient humanity
Creighton's Tyler Dunn holds the 150,000-year-old tooth of a young girl known as a Denisovan. The tooth, found in Laos, is one of only a handful of known fragments left by the ancient human group.
The tooth belonged to a young girl – somewhere between 3 ½ and 8 years old. It was unerupted, still embedded deep within her jaw when she died in southeast Asia, in the modern country of Laos, roughly 150,000 years ago.
The girl’s remains, alongside those of other ancient mammals, were washed into a cave by slow-moving water. Over the years, the remains deteriorated – even the bone – until only the tooth was left. The sediment around it hardened like concrete, and there it remained until 2018 when a team of paleontologists, bioanthropologists and archaeologists pulled it from the rock.
But from this one small tooth, scientists – including Creighton University’s Tyler Dunn, PhD – have been able to paint a more detailed portrait of the ancient human past. The girl belonged to a little-known group of ancient humans known as the Denisovans who, though extinct today, share DNA with modern peoples in Australia and the Pacific Islands.
“This group of human ancestors was only known previously from two other sites – one in Siberia and the other in Tibet,” says Dunn, assistant professor in the Department of Medical Education and director of the Anatomy Lab in the School of Medicine. “This discovery is sort of connecting the dots between where we know the fossils to be – in northern Siberia and Tibet – all the way down to islands in southeast Asia, where their modern descendants live.”
Dunn, who participated in the excavation, is one of the co-authors of the study about the discovery, published earlier this month in the journal Nature Communications. News of the find has been reported in the New York Times, National Geographic and elsewhere.
The find, Dunn says, will likely result in a renewed scientific interest in southeast Asia, a region that’s long been overlooked due to decades of war and conflict.
“I think there will be renewed excavations and expanded questions in that part of the world,” he says. “A lot of human evolution happened there.”
The Denisovans, Dunn says, remain a mystery in many ways. The only evidence they’ve left has been found in the form of scattered bone fragments – a jawbone, a finger bone and some long bone pieces – and teeth. So, creating a picture of what their faces looked like or how they behaved is difficult.
What experts do know has been drawn from studying ancient DNA and proteins left in the bones and teeth, which tell scientists that Denisovans were similar to the more well-known Neanderthals.
“Something that I think is super cool, is that a lot of this work wouldn’t have been possible even five years ago,” Dunn says. “To study ancient variation, especially when DNA is poorly preserved, we use something called proteomics. Some folks in the Department of Biomedical Sciences at Creighton are using this method, which examines protein signatures to understand modern biology. For this project, we’re applying it to remains that are 100,000 or 150,000 years old. We’re able to extract these ancient proteins and get an idea of who these people were.”
Dunn’s own research interests lie at the intersection of modern and ancient human anatomy. In the School of Medicine, he teaches anatomy to medical students, as well as courses on the social determinants of health, including the medical humanities elective “Is Race Real: Racialization in Science and Medicine.”
The through line in his work, he says, is variation in human anatomy and how those differences have played out socially through different eras of the human experience.
It is perhaps a concept that becomes more relevant the deeper you go in human history, he says. During the time of the Laos tooth, there were as many as seven distinct human groups existing in southeast Asia.
“Variation and diversity are things that need to be appreciated in our modern context as different lived experiences are coming together,” Dunn says. “That’s directly applicable to the ancient past. There were multiple ways of living in the ancient world, as this tooth shows us.”