10,000-year-old chewing gum is full of clues about what Stone Age teens were eating

• Scientists extracted DNA from chewing gum used by teenagers almost 10,000 years ago.
• The gum provided clues into what the teenagers had eaten and their lifestyle.

DNA extracted from chewing gum used by teenagers almost 10,000 years ago has provided fascinating clues into their prehistoric diet.

Around 100 pieces of the black gummy resin, complete with tooth marks, were found in Sweden's Huseby Klev archaeological site about 30 years ago.

A new study of three of these pieces of resin has produced a snapshot of the life of a small group of hunter-gatherers on the Scandinavian west coast, Anders Götherström, a professor of Palaeogenetics who led the research, said in a press release.

About 9,700 years ago, a group of teenage hunter-gatherers were camping. After fishing, hunting, and collecting materials for food, a few teenagers, including two males and one female, sat down to eat a meal, while chewing resin.

The gum revealed this meal included hazelnuts, trout, fox, duck, and deer.

One teen had a hard time eating the deer meat and masticating the gum. DNA left behind by bacteria from her teeth suggests she had periodontitis, which is a severe gum infection.

"She would probably start to lose her teeth shortly after chewing this gum. It must have hurt as well," Götherström told The Guardian.

The gum, which came from Birch trees, may have been chewed on by teenagers, to turn it into a glue that could be used to make tools and weapons.

However, "they could have been chewed just because they liked them or because they thought that they had some medicinal purpose," said Götherström.

While the study is interesting in itself, its value also lies in the new avenues it is opening to uncover secrets from other sites, Science News reported.

"It's exciting … that you could get DNA from something people chewed thousands of years ago," Lisa Matisoo-Smith, a molecular anthropologist at the University of Otago in Dunedin, told Science News.

Götherström agreed. The fact that we can now get all that information from something that was chewed provides insights that you can't get by looking at bones, teeth, or plaque, which are techniques commonly used by labs elsewhere, he told The Guardian.

"There is a richness of DNA sequences in the chewed mastic from Huseby-Klev, and in it we find both the bacteria that we know are related to periodontitis, and DNA from plants and animals that they had chewed before," said Emrah Kırdök, a biotechnologist who worked on the study.

The work was published in the peer-reviewed journal Scientific Reports on Thursday.