Archaeologists frequently recover bone tools and jewelry from ancient sites but lack the means to identify what humans used them tens of thousands of years ago, unless the artifacts are found in specific graves.
That could be changing, however, with the discovery and careful analysis of a 20,000-year-old deer tooth pendant from the famous Denisova Cave in the Altai Mountains in Russia. Using a new method, the researchers concluded from DNA evidence that the pendant’s owner, and perhaps creator, was an Ancient North Eurasian woman.
Finding Ancient DNA Without Destroying It
The discovery began as a quest to analyze the DNA attached to bone and tooth artifacts without damaging them, which is not easy. Normal DNA extraction destroys a certain amount of bone, and extraction of DNA through harsh chemicals can damage the specimens themselves.
To find alternatives, the researchers submerged animal bones discovered at Stone Age sites in four gentler chemicals to test the results. While two appeared to damage the bones, the others seemed to stop at removing surface-level sediments and chemicals, such as DNA left behind by sweat.
The winning chemical, sodium phosphate, moved to the next stage of the project, in which the researchers submerged 11 bones (from an archaeological site in France) in the chemical and looked for DNA. While early humans had used the bones as tools 35,000 to 45,000 years ago, the vast majority of the DNA found on them came from modern humans – archaeologists and others who had handled them much more recently. This dashed any hopes of sorting out the identity of the original owners.
Another Attempt at Preserving Ancient DNA
Next, the researchers traveled to sites at Bacho Kiro Cave in Bulgaria and Denisova Cave and brought along gloves and face masks. From both areas, they collected freshly excavated tooth pendants, animal teeth with holes in the top to permit some type of cord. Through careful handling, they hoped to weed out enough of the modern DNA for the ancient DNA to peek through.
They washed the artifacts and exposed them to sodium phosphate at different temperatures and recovered the most DNA from the hottest temperature, 194 degrees Fahrenheit, just shy of boiling. Ultimately, the pendant from Denisova yielded the best mitochondrial DNA sample, the one the researchers tied to a 19,000-year-old female.
In wearing or carrying the artifact, this woman had left enough genetic material behind for the new process to detect in the modern day. Whether she fashioned the hole in the deer tooth, or someone else did, the study couldn’t say.
According to further genetic analysis, she likely belonged to one of two Siberian groups, the Mal’ta from 24,000 years ago or the Afontova Gora from 17,000.
Her links to modern humans likely arose long after her death, when Stone Age Siberians made the trek over the Bering Sea land bridge to the Americas.
The Famous Denisova Cave
Denisova Cave is a well-trodden site home to 20-plus layers of excavation, where ancient humans, Neanderthals and Denisovans once lived and interbred, to varying degrees. In 2010, scientists sequenced the mitochondrial DNA of the Denisovans and introduced them to the world as a new species of early human.
The site also contains the earliest evidence, to date, of early human bone points and pendants in Northern Eurasia.
