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Theis Jensen, a bioarchaeologist at the University of Copenhagen, and colleagues, published a report in Nature Communications about a the finding of a South Danish Neolithic woman’s complete genome and oral microbiome from a piece of birch tar she chewed. This isn’t the first time this was line of evidence was used, nor the oldest, but it is the most revealing and insightful. Below is an image of the piece of gum they found and analyzed.

A 5,700-year-old piece of birch tar, chewed as gum, contains the genome, mouth microbes, and even dietary information about its former chewer. (Theis Jensen)

This piece of gum was used by a woman with brown hair and blue eyes depicted in an artist illustration below. She was part of a small fishing village in southern Denmark at the end of the Stone Age. This gum comes from the tar of birch which could have been chewed to repair a flint tool, a piece of pottery or simply used as pleasurable piece of chewing gum. Once she was done with it, it was discarded.

An artist’s illustration of what the Scandinavian person who chewed the ancient piece of gum may have looked like. (Tom Björklund)

It was not not until 5,700 years later that this piece of gum and the ancient DNA it contained was discovered. In a sense, this artifact was almost sterile, sealed in an oxygen free layer of sand and silt allowing it to preserve the only piece of human remains found at the site.

Studying the ancient DNA, the team identified bacteria that cause periodontal disease. They also found out the woman carried Epstein Barr, a virus that causes mononucleosis. She also had the bacteria Streptococcus pneumoniae, which can cause pneumonia today and is responsible for a million or more deaths each year. She was lactose intolerant. She ate hazelnut (Corylus avellana) and mallard (Anas platyrhynchos), as fragments of those two species DNA were also found within the gum.

She was a hunter-gatherer, not related to communities of farmers that lived in Denmark around the same time. A descendant of Western hunter-gatherers, who began settling in Scandinavia via a southern route as early as 11,700 years ago, she did not have the same oral microbiome as farmers did because they had more availability to carbohydrate-rich foods.

This birch material is scattered all around Scandinavia from the Stone Age to the Iron Age, and they preserve ancient DNA extremely well. As you can see they provide a wonderful snapshot into daily prehistoric life. Looking forward to more studies of this type and more advances in ancient DNA analysis.