Prehistoric Chewing Gum Reveals Diet, Oral Health of Stone Age Teenagers

From preserved DNA, researchers identified which plants and animals the young people would have eaten or used for making clothing—and they found one case of a severe gum infection

Three casts of chewing gum showing human bite marks
Casts of the ancient chewing gum pieces, which were found in Sweden and date to between 9,540 and 9,890 years ago. Verner Alexandersen

Scientists are learning about the oral health and diets of Stone Age people from analyzing ancient chewing gum. By looking at DNA in chewed plant resin dug up in Sweden, researchers painted a picture of prehistoric life based on what people had in their mouths.

They found DNA from different animals, fruit and nuts, as well as microbes tied to a gum infection, the team writes in a paper published last week in the journal Scientific Reports.

“We are capturing a moment in the Stone Age with great detail,” Emrah Kırdök, who studies ancient DNA at Mersin University in Turkey and is the first author of the study, tells Atlas Obscura’s Olivia Young.

Ancient chewing gum probably wasn’t for blowing bubbles. Hunter gatherers likely chewed the resin for a more practical reason: “to be used as glue” for making tools and weapons, Anders Götherström, a co-author of the study who studies ancient DNA at Stockholm University, tells the Agence France-Presse (AFP).

“This is a most-likely hypothesis—they could have been chewed just because they liked them or because they thought that they had some medicinal purpose,” he adds to the publication.

Today, that chewing gum can reveal insights into Stone Age people. Scientists in 2019, who studied human DNA in chewing gum from the same Swedish site as the recent study, proposed resin could preserve details about the ecology and environment of prehistoric humans. The same year, another paper looked at 5,700-year-old chewed birch tar from Denmark to reconstruct the genome of the person who chewed it, the microbes in their mouth and what they ate.

In the new study, the researchers examined three pieces of the chewed resin that date to between 9,540 and 9,890 years ago. The pieces were made from birch bark resin, the study authors write in the Conversation. They came from a site called Huseby Klev north of Gothenburg, Sweden, where archaeologists dug up flint artifacts and 115 pieces of chewed resin in the early 1990s.

Some of the newly examined pieces were preserved with imprinted tooth marks, which suggest they were chewed by three children between the ages of five and 11, as well as three teenagers, per the study.

To learn about the oral health of these people, the researchers compared the microbes found in the resin to modern datasets of both healthy and unhealthy mouth microbiomes. The results showed signs of a severe gum infection called periodontitis in one of the teenagers.

People at the time used their teeth as tools, which would have increased their risk for acquiring microbes that cause periodontitis, the study authors write. But the chewing gum could have helped with this.

“If the pitch removed plaque and debris from the tooth surface, there could have been some benefit,” Marin Pilloud, an anthropologist focused on dental anthropology at the University of Nevada, Reno, who did not contribute to the findings, tells Atlas Obscura.

The researchers also found DNA from a number of animals, including red deer, wolf, red fox, arctic fox, mallard, European robin and European turtle dove, per the study They also detected a fish from the salmon family they suggest is brown trout, but due to a lower quality of the genome, they can’t say for certain. The team found evidence of fruit and nuts, including hazelnut, apple and crab apple.

Identifying these remains in the gum is supported by other archaeological research that has found remains of these species in the area.

The gum chewers weren’t necessarily eating the meat of all these animals. They could have chewed on tendons and furs from foxes to make textiles, the study authors write in the Conversation.

Painting this clearer picture of Stone Age people, the team says, was only possible by examining chewing gum.

“If we do a human bone then we’ll get human DNA. We can do teeth and then we’ll get a little bit more. But here we’ll get DNA from what they had been chewing previously,” Götherström tells the AFP. “You cannot get that in any other way.”

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