Ancient Bubblegum

Our mesolithic ancestors used to chew on pitch materials not only to create an adhesive glue for their tools – but also for fun when they were bored. However, this habit might have been detrimental to their oral health, according to a study that investigated oral microbiome compositions from 10,000 years ago (1). 

These chewed pitch materials contain ancient DNA (aDNA) from human cells and microbes found in the mouth of our Mesolithic ancestors – making them an ideal target for genetic and genomic analysis. The catch? “aDNA is a degraded material. It often breaks down into small fragments and contains nucleotide lesions. This kind of damage accumulates over time and makes bioinformatic analysis much more complex than analyzing modern DNA data,” explains Emrah Kırdök, Assistant Professor at Mersin University, Department of Biotechnology, and corresponding author. 

After carefully extracting aDNA from three chewed pitch samples of Swedish origin, the team conducted DNA alignment analysis to compare the nucleotide identity of each aDNA sequence to a reference genome database – adapting alignment parameters to accommodate more nucleotide substitutions, classifying more aDNA reads and calculating the abundances of each microbe in the chewed pitch materials. 

An increased abundance of periodontitis-associated microbes was shown – a finding that the researchers decided to investigate further. Employing machine learning, they were able to calculate the probability of a periodontitis-like microbiome. A sequence matching red fox DNA was also identified – suggesting that people chewed red fox fur or bones to create textile materials or tools. These data demonstrate how people used several resources from the environment – practices that consequently made up the Mesolithic diet and lifestyle. 

“It is thought that the people in the Mesolithic period did not have bad oral health, because teeth material found in this context do not contain any morphological lesions related to caries or other oral pathological conditions. However, our study suggests that the frequent pitch chewing could increase the risk of collecting periodontitis like microbes, thus increasing the risk of having oral disease,” says Kırdök. 

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