Ancient chewing gum dating back to the Ice Age has led to the discovery of the oldest human DNA ever found in Scandinavia. The DNA samples belong to three individuals – two females and one male – and are around 10,000-years-old.
While a few human bones of this age have turned up in previous archaeological digs in the northern European country, those specimens didn't hold enough DNA material for analysis, Phys.org is reporting. As such, the newfound samples – preserved in ancient lumps of masticated chewing gum – have been deemed the oldest Scandinavian human DNA known to science.
The credit for this incredible discovery goes to a team of scientists from Stockholm University in Sweden and the University of Oslo in Norway, who analyzed the ancient chewing gum and extracted the DNA samples. In a study published today in the journal Communications Biology, the researchers give a full account of how the specimens were obtained and argue that the DNA samples provide an interesting "connection between material culture and genetics of Mesolithic hunter-gatherers in Scandinavia."
"Much of our history is visible in the DNA we carry with us, so we try to look for DNA wherever we believe we can find it," said study senior author Anders Götherström, a professor at Stockholm University's Archaeological Research Laboratory, where the analysis was conducted.Interestingly enough, the ancient chewing gum that yielded the oldest Scandinavian human DNA was originally uncovered nearly three decades ago. The masticates were discovered in the early 1990s at Huseby-Klev, an early Mesolithic hunter-fisher site located on the Swedish west coast.
Made out of birch bark pitch, the chewing gum masticates were left behind by the first humans who settled in Scandinavia more than 10,000 years ago, notes Phys.org, citing Stockholm University. According to university officials, the ancient material was used as glue in tool production.Nowadays, ancient chewing gum is seen as an alternative source for human DNA and can even double as a decent proxy for human bones in genetic studies on archaeological samples. However, science didn't possess the means to extract and analyze ancient human DNA at the time that the masticates were found, especially since they were contained within non-human tissue.
As a result, the masticates were stored away shortly after being found. It was only 30 years later that their secret could finally be unraveled thanks to the laborious work of a group of scientists led by Natalija Kashuba, a researcher at the University of Oslo's Museum of Cultural History and a Ph.D. student at Uppsala University in Sweden. As she pointed out, her team was "really impressed that archaeologists took care during the excavations and preserved such fragile material."
"It took some work before the results overwhelmed us, as we understood that we stumbled into this almost 'forensic research,' sequencing DNA from these mastic lumps, which were spat out at the site some 10,000 years ago."After analyzing the ancient human DNA, the researchers learned that the three individuals from Huseby-Klev were closely linked to other hunter-gatherers in Sweden and to early Mesolithic populations from Ice Age Europe, sharing more generic similarities to western hunter-gatherer tribes rather than eastern hunter-gatherer populations.
Meanwhile, the tools uncovered at the Huseby-Klev site "were a part of lithic technology brought to Scandinavia from the East European Plain, modern day Russia," shows Phys.org. This suggests that the genetic material and cultural elements found in Scandinavia may have arrived in the Nordic peninsula by two different routes – a hypothesis formulated by previous other studies as well.The ancient chewing gum samples found at Huseby-Klev add support to this theory, as they provide a direct link between the tools produced at the site and human genetics, explains Stockholm University.
"DNA from these ancient chewing gums have an enormous potential not only for tracing the origin and movement of peoples long time ago, but also for providing insights in their social relations, diseases and food," says study co-author Per Persson of the Museum of Cultural History in Oslo.