A new study of the DNA present in 10,000-year-old chewing gum found on the coast of Scandinavia shows that the diet of those who chewed it included deer, trout and hazelnuts. It also reveals that one of the subjects had serious dental problems. Birch tar gums reflect this and other information about the diet of our ancestors.

An investigation carried out by 13 researchers belonging to institutions in Finland, Norway, Sweden and Turkey and published this Thursday in the journal Scientific Reports presents the findings. About 9,700 years ago, a group of people camped on the western coast of Scandinavia, north of what is now Gothenburg, Sweden. They had been fishing, hunting, and gathering resources to feed themselves.

Some teenagers, both boys and girls, chewed resin to produce glue, right after eating trout, deer and hazelnuts. Due to a severe case of periodontitis (a type of serious gum infection that can lead to tooth and bone loss), one of the teens had trouble eating the venison, as well as chewing the birch tar.

“There is a great wealth of DNA sequences in the chewed putty from the Huseby-Klev site, on the island of Orustfue, and in it we found both the bacteria that we know are related to periodontitis and the DNA of plants and animals that had chewed before,” says Dr. Emrah Kirdök from the Department of Biotechnology at Mersin University, who coordinated the metagenomic work on Mesolithic chewing gum, in a statement.

The chewed material from Huseby Klev has generated a study of human genetic data from three individuals, and DNA from non-human material has also been analyzed and published. Identifying the different species present in the type of DNA mixture that was present in Mesolithic ‘gum’ was a challenge. Andrés Aravena, from the Department of Molecular Biology and Genetics at Istanbul University, Turkey, spent a lot of time at the computer analyzing the data together with Kirdök.

“We had to apply several computer analytical tools to identify the different species and organisms. All the tools we needed were not ready to be applied to ancient DNA,” says Aravena.

Anders Götherström, from the Center for Paleogenetics, a joint institution of Stockholm University and the Swedish Museum of Natural History, points out that this study offers “a snapshot of the life of a small group of hunter-gatherers on the Scandinavian west coast.”

“Surprisingly, there are other well-established methods for determining what nutrition and diet relate to the Stone Age, but here we know that these teenagers ate deer, trout and hazelnuts 9,700 years ago on the western coast of Scandinavia, while at least one of them had serious dental problems,” he concludes.