Several years ago, a 20,000-year-old piece of jewelry made from an elk tooth was found in southern Siberia. Now, thanks to a newly developed method for extracting DNA from porous artifacts, researchers have determined the pendant’s last wearer was a woman or girl who hailed from a region some 1,200 miles away.
The new technique, outlined in a recent paper published in the journal Nature, has the potential to help researchers unlock ancient DNA from other very old items—and potentially even identify those who touched or wore them.
Researchers have had great success extracting and analyzing DNA from ancient teeth, bones and other remains. But for years, they’ve tried—and failed—to do the same with jewelry, tools, ornaments and other artifacts without causing damage.
Scientists at the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) in Leipzig, Germany, decided to try cracking the code once and for all. They spent years testing various methods to extract human DNA—left behind in skin cells or sweat—from artifacts made of porous materials, such as teeth or bones.
Eventually, the researchers developed a winning technique. They learned they could gradually tease out ancient DNA trapped inside a porous material by submerging the entire object in a sodium phosphate solution, then slowly heating the liquid to around 194 degrees Fahrenheit. As the temperature increased, DNA stored deep inside the object emerged. This method leaves the artifact undamaged.
As they fine-tuned the technique, the researchers learned that it didn’t work on artifacts that were contaminated by DNA from today’s archaeologists. It also failed when items were buried in certain soil types.
In 2019, a visiting archaeologist handed over a plastic bag that held a Paleolithic tooth pendant. Found inside Siberia’s Denisova Cave—which has been used at various points by humans, Neanderthals and Denisovans—the tooth had a hole drilled through it, suggesting it may have been worn on a bracelet or headband. Holding the tooth in the lab’s clean room, Elena Essel, a molecular biologist at MPI-EVA and first author of the study, found herself daydreaming about the person—or people—who last touched it.
“As I looked at the object, a flood of questions came to mind,” she tells Reuters’ Will Dunham. “Who was the person who made it? Was this tool passed down from one generation to the next, from a mother to a daughter or from a father to a son? That we can start addressing these questions using genetic tools is still absolutely incredible to me.”
Importantly, the pendant was still encased in dirt from its original burial site, and the archaeologists who unearthed it had been wearing coveralls, masks and gloves. These factors helped prevent contamination, which allowed the researchers to complete the extraction successfully.
Some of the DNA they found came from the tooth itself, which belonged to an elk. But the pendant also contained DNA from a human female who was closely related to a group of hunter-gatherers, known as the Maltinsko-buretskaya, who lived east of the cave near Lake Baikal.
“Forensic scientists will not be surprised that human DNA can be isolated from an object that has been handled a lot,” says study co-author Matthias Meyer, an evolutionary geneticist at MPI-EVA, in a statement. “But it is amazing that this is still possible after 20,000 years.”
By learning more about who last handled artifacts, scientists will gain new insights into “cultural practices and social structure in ancient populations,” says Beth Shapiro, an evolutionary biologist of the University of California, Santa Cruz who was not involved in the research, to Science’s Ann Gibbons. For example, extracted DNA could provide evidence for trade between certain groups or shed light on how men and women used certain tools or objects.
As João Teixeira, a geneticist at the Australian National University who was not involved in the study, tells the Australian Broadcasting Corporation’s Belinda Smith, “It’s now fair game for us to look at these types of objects and to seriously think about the possibility of matching the species that made or used these kinds of objects to their culture.”