DNA From Ancient Gum Reveals Secrets of Stone Age Dentistry

Mesolithic Scandinavians likely faced oral health issues, with studies on ancient birch tar revealing signs of gum disease, tooth decay, and diverse dietary habits.

Members of a hunter-gatherer group that lived in south-western Scandinavia during the Mesolithic era — approximately 10,000 years ago — may have been affected by tooth decay and gum disease, according to a study published today (January 18) in Scientific ReportsEstablished in 2011, <em>Scientific Report</em>s is a peer-reviewed open-access scientific mega journal published by Nature Portfolio, covering all areas of the natural sciences. In September 2016, it became the largest journal in the world by number of articles, overtaking <em>PLOS ON</em>E.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Scientific Reports.

DNA Analysis of Birch Tar

Emrah Kırdök, Anders Götherström, and colleagues sequenced the DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>DNA found on three pieces of birch tar — a substance made from heated birch bark — that were excavated in the 1990s from Huseby Klev, Sweden and have been dated to between 9,890 and 9,540 years old. They created profiles of the microbial, plant, and animal speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>species DNA found on each sample and compared these to those previously reported for modern human samples, ancient human dental plaque, and a 6,000-year-old chewed birch tar sample.

Findings on Oral Health

The authors found that the microbial profiles of the birch tar samples were most similar to microbes found in the modern human mouth, in ancient human dental plaque, and in a 6,000-year-old chewed birch tar sample. This suggests that the samples from Huseby Klev were chewed by humans. They also found that they contained an increased abundance of several bacteria that are commonly associated with gum disease — such as Treponema denticola, Streptococcus anginosus, and Slackia exigua — and tooth decay — such as Streptococcus sobrinus and Parascardovia denticolens.

Based on the relative abundance of microbial species in the birch tar samples and using machine learningMachine learning is a subset of artificial intelligence (AI) that deals with the development of algorithms and statistical models that enable computers to learn from data and make predictions or decisions without being explicitly programmed to do so. Machine learning is used to identify patterns in data, classify data into different categories, or make predictions about future events. It can be categorized into three main types of learning: supervised, unsupervised and reinforcement learning.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>machine learning models, the authors estimate that the probability that members of the hunter-gatherer group were affected by gum disease is between 70 and 80%. The authors suggest that the wider use of teeth to perform tasks involving gripping, cutting and tearing in ancient hunter-gatherer societies may have increased their risk of coming into contact with microbial species that cause gum disease.

Insights into Diet and Material Use

In addition to microbial DNA, the authors identified DNA sequences consistent with those from a range of plant and animal species, including hazelnut, apple, mistletoe, red fox, grey wolf, mallard, limpet, and brown trout. These could reflect the materials that members of the hunter-gatherer group chewed prior to the birch tar samples. The authors speculate that these materials could have included food sources, furs, and bone tools.

Conclusions on Mesolithic Oral Health

The findings highlight the poor oral health of a group of Mesolithic Scandinavian hunter-gatherers and provide insight into their diet, material use, and local environment.

Reference: “Metagenomic analysis of Mesolithic chewed pitch reveals poor oral health among stone age individuals” 18 January 2024, Scientific Reports.
DOI: 10.1038/s41598-023-48762-6