Oral Microbiome and Diet: Researchers Analyze DNA From Ancient “Chewing Gum”

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What did people consume along the west coast of Scandinavia 10,000 years ago? A recent study involving the analysis of DNA found in a piece of chewed resin provides insights into their diet. It reveals that their food included deer, trout, and hazelnuts. Additionally, the study highlights that one individual among them had significant dental issues.1

An international research team has been studying the chewed resin from Huseby Klev for some time. This material contains a wealth of DNA sequences, including bacteria associated with periodontitis, as well as DNA from the plants and animals they had consumed earlier.1

The Study

Previous research on ancient dental calculus offers insights into the types of microbes present in the formation and development of dental biofilm, along with its link to oral health. Furthermore, this field allows for the exploration of how the oral microbiome has evolved over different archaeological eras.1

For instance, the shift from hunter-gatherer lifestyles to agricultural practices marked a notable increase in oral health issues, correlating with changes in diet and way of life. Numerous studies utilizing ancient DNA have identified the evolution of the oral microbiome from the Mesolithic era to the present, examining its connection with dietary shifts, population migrations, and the impact of contact between pre and post-Columbian societies.1

Additionally, these studies can detect dietary residues and DNA sequences that shed light on ancient environmental conditions through the analysis of ancient DNA and microscopic investigations.1

The research began with Dr. Emrah Kırdök, who analyzed the material during his postdoc at Stockholm University. The excavation site at Huseby Klev on Orust Island, which took place 30 years ago, revealed chewed resin alongside stone tools, dating back approximately 9,700 years to the Mesolithic period.2

The current study used metagenomic analysis, which identifies the structure and function of entire nucleotide sequences in a bulk sample, to identify oral microbiome profiles in three different chewed resin pieces. The researchers then compared the data with modern oral microbiomes, looking to identify differing oral microbes that may have emerged due to dietary and lifestyle changes.1

The Results

Through a comparison of findings with modern oral microbiomes, the researchers highlight a higher prevalence of oral microbes potentially linked to pathological conditions like periodontitis. Additionally, this research offers DNA-based insights into dietary elements and potential paleoenvironmental eukaryotes associated with the Huseby Klev archaeological site.1

The analysis revealed 51 distinct bacterial genomes. A significant portion of these genomes are from bacteria that are either pathogenic or capable of causing disease under certain conditions. Notably, the authors detected sequences from Porphyromonas gingivalis and Treponema denticola, which are part of the red complex – a collection of species commonly associated with periodontitis.1

Additionally, they found Aggregatibacter actinomycetemcomitans and Streptococcus mutans, among others. Moreover, across all samples, they observed the presence of Haemophilus influenzae, Aggregatibacter actinomycetemcomitans, Cardiobacterium valvarum, Eikenella corrodens, and Kingella denitrificans.1


Metagenomics on ancient DNA is a developing field, and only a few studies have been conducted on this type of chewed material. Professor Anders Götherström, head of the project at the Centre for Palaeogenetics, highlights that this research provides a snapshot of the lives of a small group of hunter-gatherers on the west coast of Scandinavia. It offers fascinating insights into their Stone Age diet, which included deer, trout, and hazelnuts, while also shedding light on the dental health challenges faced by at least one of them.1,2

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  1. Kırdök, E., Kashuba, N., Damlien, H., et al. Metagenomic Analysis of Mesolithic Chewed Pitch Reveals Poor Oral Health Among Stone Age Individuals. Scientific Reports. 2024; 13(1): 22125. https://doi.org/10.1038/s41598-023-48762-6
  2. Stockholm University. (2024, January 18). Ancient ‘Chewing Gum’ Reveals Stone Age Diet. ScienceDaily. www.sciencedaily.com/releases/2024/01/240118122104.htm