About 10,000 years ago, a group of hunter-gatherers were hanging out in what is now south-western Sweden chewing pieces of birch tar. New analysis of that substance reveals that they may have had very modern dental issues.
The birch tar samples, which were likely chewed to create a kind of glue, were first excavated in the 1990s in Huseby Klev, Sweden. While they've been studied before, a team of researchers, led by Emrah Kırdök from Mersin University in Turkey, developed cutting-edge methods to analyze the ancient DNA contained in the samples.
"We had to apply several computational heavy analytical tools to single out the different species and organisms," said study co-author Andrés Aravena from the Department of Molecular Biology and Genetics at Istanbul University.
"All the tools we needed were not ready to be applied to ancient DNA, but much of our time was spent on adjusting them so that we could apply them."
Once the analysis tools were in place, the team got busy looking at the resin samples. The scientists found that the birch tar had been chewed by teenagers in the group, who had likely recently eaten deer, trout, and hazelnuts. The bacteria associated with modern-day dental disease was also discovered, which means that at least one of the teens was likely suffering from periodontitis, an infection that damages the soft tissue around the teeth and can lead to bone and tooth loss.
Bacteria associated with tooth decay was also discovered. The researchers estimate that the members of this particular Scandinavian group had gum disease at a rate of about 70 to 80%.
In addition to the hazelnuts, trout, deer, and dental bacteria discovered in the samples, the team also found DNA sequences from other plants and animals including apple, red fox, grey wolf, and mistletoe. The team says that some of those traces could have been left behind from members of the community using their teeth as tools to, for example, create clothing out of the fur from the wolves and foxes. Interestingly, such activities could also have contributed to gum disease, as the people taking part in them would have exposed their mouths to a wide range of bacterial invaders.
"This provides a snapshot of the life of a small group of hunter-gatherers on the Scandinavian west coast," summed up Stockholm University's Anders Götherström, who was also involved in the research. "I think it is amazing, there are other well-established methods to work out what nutrition and diet relates to the Stone Age, but here we know that these teenagers were eating deer, trout, and hazelnuts 9,700 years ago on the west coast of Scandinavia, while at least one of them had severe problems with his teeth."
The study has been published in the journal, Scientific Reports.
Sources: Stockholm University, Scientific Reports via EurekAlert
