Ancient Chewing Gum: Stone Age Diet Revealed

Archaeologists have uncovered a fascinating snapshot of life in the Mesolithic era through an unlikely source: ancient chewing gum. A recent study of 9,700-year-old birch pitch found in Scandinavia has provided unprecedented details about what teenagers ate, how they lived, and even the state of their dental health nearly ten millennia ago.

The Discovery at Huseby Klev

The excavation site is located at Huseby Klev on the west coast of Sweden, north of Gothenburg. While the site was originally excavated in the early 1990s, the significance of the chewing gum samples—lumps of black pitch made from birch bark—was not fully realized until modern genomic testing became available.

Researchers from Stockholm University, led by Anders Götherström, re-examined these ancient masticated lumps. Unlike bones or tools which give us clues about structure and industry, these pitch samples contained trapped saliva. This preserved the DNA of the individuals who chewed them, along with the DNA of the food they had recently consumed and the bacteria living in their mouths.

What Is Birch Pitch?

Birch pitch is a dark, glue-like substance created by heating birch bark. In the Stone Age, it was a critical technological material. It served as an adhesive to attach stone blades to wooden handles (hafting) or to repair broken tools.

However, to make the pitch pliable enough to use, it had to be warm or chewed. The presence of tooth marks on the Huseby Klev samples suggests that adolescents, regardless of gender, were tasked with chewing the resin to keep it soft for toolmakers.

The Stone Age Menu: Deer, Trout, and Hazelnuts

The most exciting aspect of the study published in Scientific Reports is the concrete evidence of the Mesolithic diet. By sequencing the DNA found inside the pitch, scientists reconstructed a specific menu that the chewers had eaten shortly before popping the “gum” into their mouths.

The analysis identified DNA from the following food sources:

• Red Deer: This appears to have been a primary source of protein. The prevalence of deer DNA suggests organized hunting was a daily necessity.
• Brown Trout: Fishing was clearly vital for this coastal community. The specificity of the DNA rules out general seafood and points directly to trout.
• Hazelnuts: This was a staple gathered food. Hazelnuts are high in fat and protein, making them an excellent energy source for hunter-gatherers.
• Mallard Duck: Bird consumption was also detected, adding variety to the diet.
• Fox: Interestingly, DNA from foxes was found. While it is possible they ate fox meat, it is also possible the teenagers used their teeth to process fox furs and ingested the DNA accidentally.

This combination paints a picture of a diverse diet that relied on hunting, fishing, and gathering. It confirms that the people of Huseby Klev utilized their local environment efficiently to sustain themselves.

Health and the Oral Microbiome

Beyond diet, the chewing gum provided a medical record of the individuals. The saliva trapped in the pitch offered a deep look into the oral microbiome (the community of bacteria in the mouth) of these Stone Age teenagers.

The findings challenge the popular belief that ancient humans had perfect oral health before the advent of refined sugar and agriculture. The DNA analysis revealed several significant health issues:

• Gum Disease: Researchers found bacteria associated with severe periodontitis (Treponema denticola and Porphyromonas gingivalis). This indicates that these individuals likely suffered from painful gum inflammation and potential tooth loss.
• Tooth Decay: Traces of Streptococcus mutans, the primary bacteria responsible for cavities, were present. Even without candy bars, the carbohydrates from nuts and natural sugars were enough to cause decay.
• Systemic Illness: The gum contained more than just oral bacteria. The team found traces of Staphylococcus, as well as the Epstein-Barr virus (which causes mononucleosis) and bacteria related to pneumonia.

This suggests that despite an active lifestyle and a “natural” diet, these individuals struggled with chronic health issues that are still common today.

Why Were They Chewing It?

While the primary use of birch pitch was technological (as a glue), researchers believe there were other reasons these teenagers spent hours chewing it.

1. Tool Preparation: As mentioned, the resin hardens when cool. Chewing it made it sticky and workable for fixing arrowheads or scrapers.
2. Medicinal Use: Birch bark contains betulin, which has natural antiseptic and anti-inflammatory properties. Given the high rates of gum disease and tooth decay found in the samples, chewing the pitch might have provided soothing relief for aching teeth.
3. Hunger Suppression: Similar to how modern people chew gum to curb appetite, the pitch may have helped distract from hunger during long periods between successful hunts.
4. Cleaning: The abrasive nature of the pitch could have functioned as a primitive toothbrush, helping to remove food particles from teeth, even if it didn’t prevent cavities entirely.

The Significance of Ancient DNA (aDNA)

This study highlights the rapid advancement of ancient DNA (aDNA) technology. Just two decades ago, archaeologists relied mostly on physical examination of bones and artifacts. Today, they can sequence genomes from saliva trapped in resin for thousands of years.

This method allows scientists to look at soft data—like viruses, bacteria, and digested food—that leaves no fossil trace. It transforms a lump of ancient trash into a biological time capsule, offering a direct link to the daily lives of prehistoric people.

Frequently Asked Questions

How old is the chewing gum found in Sweden? The birch pitch samples from Huseby Klev have been dated to approximately 9,700 years ago, placing them in the Mesolithic period.

Did Stone Age people really chew gum for fun? While it is possible they chewed it for enjoyment, the primary purpose was likely functional. They chewed the pitch to make it soft enough to use as glue for making tools. However, it also likely served medicinal purposes or helped clean their teeth.

What specific diseases did the researchers find? The researchers found DNA evidence of gum disease (periodontitis), tooth decay (Streptococcus mutans), pneumonia, and the Epstein-Barr virus.

Is birch pitch safe to chew today? Birch pitch is natural, but making it requires a specific heating process (dry distillation). While generally non-toxic, it has a tar-like taste and texture that most modern people would find unpleasant compared to commercial gum.

Who chewed the gum? Based on DNA and previous analysis of tooth imprints on similar samples, the chewers were both male and female, and they were primarily teenagers or young adults.