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10,000-yr-old chewing gums reveal the oldest Scandinavia human DNA

A recently published study conducted at Sweden’s Stockholm University claims to have found the oldest human DNA ever sequenced from Scandinavia in ancient chewing gums spat out 10,000 yrs ago. Made from birch bark pitch, they contained DNA from 2-females & 1-male. The pieces came from a site on the Swedish west coast, excavated in the 1990s.

The first humans who settled in Scandinavia more than 10,000 years ago left their DNA behind in ancient chewing gum, masticated lumps made from birch bark pitch. This is shown in a new study conducted at Stockholm University & published in Communications Biology.

Few human bones of this age have been found in Scandinavia & not all of them have preserved enough DNA for archaeogenetic studies. In fact, the DNA from these newly examined chewing gums is the oldest human DNA ever sequenced from this area. The DNA, derived from two females & one male, creates an exciting link between material culture & human genetics.

Ancient chewing gum is considered an alternative source for human DNA & possibly a good proxy for human bones in archaeogenetic studies. The investigated pieces come from Huseby-Klev, an early Mesolithic hunter-fisher site on the Swedish west coast. The site excavation was done in the early 1990s, but it was not possible to analyze ancient human DNA then, let alone that embedded in non-human tissue. The masticates were made out of birch bark tar & used as glue in tool production & other types of technology during the Stone Age.

“When Per Persson & Mikael Maininen proposed to look for hunter-gatherer DNA in these chewing gums from Huseby Klev we were hesitant, but really impressed that archaeologists took care during the excavations & preserved such fragile material,” says Natalija Kashuba of the Museum of Cultural History in Oslo. She performed the experiments in cooperation with Stockholm University.

“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,” says Kashuba. Today, she is a Ph.D. student at Uppsala University.