DNA of the first inhabitants of Scandinavia gleaned from old chewing gums

The first humans who settled in Scandinavia more than 10,000 years ago left their DNA in ancient chewing gum, masticated masses made from birch pitch. This is demonstrated in a new study conducted at Stockholm University and published in Biology of communication .

There are few human bones of this age, almost 10,000 years old, in Scandinavia, and not all of them have enough DNA for archaeogenetic studies. In fact, the DNA of these recently examined chewing gums is the oldest human DNA sequenced to date in this region.

DNA from three individuals, two women and one man, creates a fascinating link between material culture and human genetics.

Piece of birch bark chewing gum containing the oldest Scandinavian DNA (Image: Natalija Kashuba et al / Nature )

Alternative source of Scandinavian DNA

Previous DNA studies in the region were based on DNA derived from the bones and teeth of seven individuals from the Norwegian Atlantic coast and the Baltic islands of Gotland and Stora Karlsö, dating from 9,500 to 6,000 years ago, as indicated in The Conversation. The colonization of Scandinavia dates back to around 11,700 years ago and was one of the last areas in Europe to be populated when the ice retreated.

Old chewing gum is now an alternative source of human DNA and may be a good indicator of human bone in archaeogenetic studies. The pieces studied come from Huseby-Klev, one of the first Mesolithic hunter-fishing sites on the west coast of Sweden. The excavations of the sites were carried out in the early 90s, but to date, it was not at all possible to analyze ancient human DNA, let alone from non-human tissues. The putties were made from birch bark tar and used as glue in the manufacture of tools and in other types of technology during the Stone Age.

This is an excavation of the Huseby-Klev site in the 1990s. (Per Persson / Stockholm University)

"When Per Persson and Mikael Maininen proposed to look for hunter-gatherer DNA in Huseby Klev chewing gum, we were hesitant, but we were really impressed by the fact that archaeologists took care to preserve the such fragile materials, "said Natalija Kashuba, an affiliate of The Oslo Museum of Cultural History conducted her experiments in cooperation with the Stockholm University.

"It took work before the results overwhelmed us, because we realized that we had stumbled into this" forensic research ", the sequencing of DNA from these clumps of mastic, spitting on the site about 10,000 years ago! " said Natalija Kashuba. Today, Natalija is a PhD student. student at the University of Uppsala.

The studied material and its origin. a One of Huseby Klev's chewing gum (Fynd 2037), with two plastelina molds on each side. b Location of sites, whose genomes were used in this study. (Picture: Natalija Kashuba et al / Nature )

Exciting link between material culture and human genetics

The results show that, genetically, the individuals whose DNA has been found share a close genetic affinity with other hunter-gatherers in Sweden and with the first Mesolithic populations of the Ice Age in Europe. However, the tools produced on the site were part of the lithic technology introduced in Scandinavia since the Eastern European Plain, modern Russia. This cultural and genetic influx scenario in Scandinavia from two pathways has been proposed in previous studies and these ancient chewing gums provide an interesting link between tools and materials used and human genetics.

Emrah Kirdök from Stockholm University performed the computer analyzes of DNA. "Demographic analysis suggests that the genetic makeup of Huseby Klev individuals has more similarities than western hunter-gatherer populations compared to East hunter-gatherer populations," he said. declared.

"The DNA of these ancient chewing gums has tremendous potential not only to trace the origin and movement of people, but also to provide information about their social relationships, diseases, and nutrition," Per Persson tells the Museum. of Cultural History in Oslo. "Much of our history is visible in the DNA we have with us, so we try to search for DNA wherever we think we can find it," says Anders Götherström of the Archaeological Research Laboratory in the United States. Stockholm University, where the work was carried out. The study is published in Biology of communication .

Top Image: One chewing gum containing the oldest Scandinavian DNA from Huseby Klev with two plastelina molds on each side. Source: Natalija Kashuba et al / Nature

The article & # 39; Chewing gums reveal the oldest Scandinavian human DNA " was originally published on Science Daily.

Source: Stockholm University. "Chewing gums reveal the oldest Scandinavian human DNA." ScienceDaily. ScienceDaily, May 15, 2019. www.sciencedaily.com/releases/2019/05/190515085450.htm.