Ancient 'Chewing Gum' of 5,700-Year-Old Blue-Eyed, Dark-Haired Hunter-Gatherer Analyzed by Scientists

Scientists have decoded an entire human genome from a 5,700-year-old birch sample—or ancient "chewing gum." This, they say, is the very first time a complete ancient human genome has been extracted from anything other than a human bone.

Researchers writing in the journal Nature Communications describe a female, who lived in Scandinavia circa 2,600 BCE. She most likely had dark skin, dark hair, blue eyes and an intolerance to lactose.

The results also suggest she was more closely related to the hunter-gatherers of mainland Europe than she was to other groups that might have been around at the time, including those of the Funnel Beaker culture.

The ancient female, nicknamed "Lola," contains no Neolithic farmer ancestry, despite dating to the period immediately after the Mesolithic-Neolithic transition in Denmark, researchers say. This, they add, supports evidence discovered elsewhere in Europe suggesting hunter-gatherers stuck around for longer than previously thought.

The genome dates to a period roughly 5,700 years ago—a time when the Late Mesolithic Ertebølle culture (approximately 7,300–5,900 years ago) made way for the Neolithic Funnel Beaker culture (approximately 5,900–5,300 years ago). The transition saw flaked stone artifacts and T-shaped antler axes replaced with distinctive pottery and polished flint artifacts, as well as the culture's domesticated plants and animals.

An artist's illustration of Lola
An artist's illustration of "Lola." University of Copenhagen/Tom Björklund

The birch pitch—a blackish-brown material made of heated birch bark—was found in Syltholm, southern Denmark.

"Syltholm is completely unique," Theis Jensen, a postdoc at the Globe Institute, said in a statement. "Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal."

Birch pitch like this was commonly used in ancient times as an all-purpose glue, a handy tool for forging stone tools dating back to Palaeolithic times.

Piece of birch pitch from Syltholm
Piece of birch pitch from Syltholm, southern Denmark. Theis Jensen/University of Copenhagen

Remains are frequently found with tooth imprints, an observation that suggests birch pitch was chewed. This may have been to turn the material malleable before it was used to make equipment, but it may have served other purposes. For example, as a method to relieve toothache, dampen hunger or as an ancient form of chewing gum.

Whatever its purpose in this instance, it offers an insight into the diet and health of people at the time. As well as human DNA, the researchers found traces of plant, animal and even virus DNA in the birch pitch. This includes DNA from hazelnuts and duck, suggesting possible contributions to the individual's diet.

The researchers also note the presence of what they think is the DNA of the Epstein-Barr Virus (EBV)—a pathogen that affects upwards of 90 percent of humans today, leading to illnesses like mononucleosis or glandular fever. They also found DNA of bacteria linked to pneumonia.

"Our ancestors lived in a different environment and had a different lifestyle and diet, and it is therefore interesting to find out how this is reflected in their microbiome," said lead author Hannes Schroeder, an associate professor at the University of Copenhagen.