Scientists discover DNA of ancient woman on 5,700-year-old "chewing gum"

Thanks to a 5,700-year-old piece of "chewing gum," the entire genome of a neolithic human has been obtained and analyzed. Researchers from the University of Copenhagen said it's the first time an entire ancient human genome has been obtained from anything other than human bone.

According to a study published this week in the journal Nature Communications, the young woman's DNA was obtained from teeth marks she left in ancient chewing gum. The primitive gum — which was actually heated, chewable tar from a birch tree, often used as an all-purpose glue — has been found with tooth imprints at archeological sites in the past and has provided critical information. The genetic analysis of this sample yielded insight into what this woman ate, where she was from and what kind of germs she carried in her mouth.

Scientists have constructed an image of the woman based on the DNA extracted from the specimen. She likely had dark skin, brown hair and blue eyes, and hailed from Syltholm on Lolland, a Danish island in the Baltic Sea. Researchers nicknamed the woman "Lola."

"Syltholm is completely unique. Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal," Theis Jensen, who worked on the study and also participated in the excavations at Syltholm, said in a press release.

Lola was likely more closely related to hunter-gatherers from continental Europe than those from central Scandinavia — meaning settlers of what is now Denmark may have come from modern-day Germany, for example, rather than Sweden.

There are many theories for the uses of the tar, called birch pitch. Some believe it was chewed to make it malleable enough to be used to build tools. Others suggest it could be used to relieve toothaches or other ailments, as a kind of toothbrush, to suppress hunger or for fun as regular chewing gum.

Additionally, non-human DNA found in the birch pitch included pathogens that cause glandular fever and pneumonia, as well as many other natural viruses and bacteria. Other plant and animal DNA revealed she had likely just finished a meal of hazelnuts and mallard duck — but not dairy, because she was lactose-intolerant. 

"The preservation is incredibly good, and we managed to extract many different bacterial species that are characteristic of an oral microbiome. Our ancestors lived in a different environment and had a different lifestyle and diet, and it is therefore interesting to find out how this is reflected in their microbiome," said lead researcher Dr. Hannes Schroeder.

"It can help us understand how pathogens have evolved and spread over time, and what makes them particularly virulent in a given environment," he continued. "At the same time, it may help predict how a pathogen will behave in the future, and how it might be contained or eradicated."