Rare traces of tooth decay and gum disease found in Bronze Age teeth

Keeping your teeth clean has been a pain for thousands of years, and history has used some particularly painful methods to care for our teeth. Two 4,000-year-old human teeth recently unearthed from a limestone cave in Ireland were recently found to contain “unprecedented amounts” of bacteria that can cause cavities and gum disease. Genetic analysis of these well-preserved microbiota reveals how changes in diet from the Bronze Age to today affect our oral health. The findings are described in a study published March 27 in the journal Molecular Biology and Evolution.

Fossil dental plaque is one of the best-studied parts of the ancient human body. However, complete genomes of pre-medieval dental oral bacteria have rarely been discovered. This means scientists have limited data on how the human oral microbiome was affected by changes in diet and events such as the spread of agriculture about 10,000 years ago.

Sugar, acid-producing bacteria

Both teeth belong to the same man who lived in what is now Ireland during the Bronze Age. Teeth contain bacteria that cause gum disease,

High-quality ancient genomes Streptococcus mutans (Streptococcus mutans). This oral bacteria is one of the leading causes of tooth decay.

Streptococcus mutans It is common in modern human mouths but very rare in ancient genomic records. One potential reason why it's so sparse may be the way the bacteria produce acid. Acid erodes teeth, but it also damages DNA and prevents plaque from petrifying and hardening over time. Most ancient oral microbiota are found within these fossil plaques, but the new study looked directly at teeth.

[Related: Vikings filed their teeth to cope with pain.]

another reason Streptococcus mutans The substance was probably not present in ancient people's mouths, possibly due to a lack of sugary oral cavity for it to grow. Streptococcus mutans It can be seen from the archaeological record after humans began to plant and cultivate grains that people liked to eat sugar and tooth decay increased. However, over the past few centuries, when sugary foods became more common, the increase was even more dramatic.

Microbiota disappearance hypothesis

The tooth sample was part of a larger skeleton discovered by the late Peter Woodman of University College Cork in Kilrag Cave, County Limerick. Other teeth in the cave showed severe tooth decay, but there was no evidence of caries or early tooth decay.One tooth turns out to be many amoeba sequence.

“We were very surprised to see such a large number of Streptococcus mutans “In this 4,000-year-old tooth,” study co-author Lara Cassidy, a geneticist at Trinity College Dublin, said in a statement. “This is a very rare find that shows This person was at high risk for tooth decay before death.”

An Irish preserve surrounded by greenery
Skeleton remains from 4,000 years ago have been unearthed at Killuragh Cave in Ireland. Photo credit: Sam Moore and Marion Dodd.

The cave's cool, dry and alkaline conditions may have aided preservation Streptococcus mutans DNA.Although Streptococcus mutans DNA was abundant in the tooth samples and other Streptococcus species were mostly absent. This indicates that the natural balance or oral biofilm has been altered—amoeba beyond other bacterial species.

The research team said this study provides more support for the hypothesis of the disappearance of the microbiota. This idea suggests that our ancestors' microbiomes were actually more diverse than our microbiomes today.Further evidence supporting this hypothesis comes from two genomes Tanella forsythia (Forsythia) was built by the team from the ground up. Forsythia remain present and lead to gum disease.

“Two tooth samples contained distinct bacterial strains Forsythia,” study co-author Iseult Jackson, a doctoral student at Trinity College Dublin, said in a statement. “Although these modern samples come from Europe, Japan and the United States, these strains from a single ancient mouth are more genetically different than any pair of modern strains in our dataset. This is interesting because the loss of biodiversity can have an impact on the mouth Negative impacts on the environment and human health.

Change genes and mouth

Both reconstructed genomes revealed dramatic changes in the oral microenvironment over the past 750 years.a bloodline Forsythia Dominated in populations around the world in recent years, it's a sign of an event geneticists call selective seizures. This is when a bacterial strain rapidly increases in frequency due to a specific genetic advantage.this Forsythia In particular, genomes that emerged after the Industrial Revolution acquired genes that helped it colonize the mouth and cause disease.

[Related: Bronze Age cauldrons show we’ve always loved meat, dairy, and fancy cookware.]

Streptococcus mutans There is also evidence of recent lineage expansion and changes in gene content consistent with the spread of sugar.However, modern Streptococcus mutans The population remains more diverse Forsythiaincluding some deep disagreements Streptococcus mutans The evolutionary tree predates the genome found in Ireland. The team believes this is driven by evolutionary differences underlying the genome diversity of these bacterial species.

Streptococcus mutans are very good at exchanging genetic material between strains,” Cassidy said. “This allows beneficial innovations to spread to individual strains. S. amoeba Bloodlines, rather than one bloodline becoming dominant and superseding all other bloodlines.

The nature of both disease-causing bacteria has changed dramatically from the Bronze Age to the present. However, recent cultural shifts, such as greater sugar consumption, appear to be having a dramatic impact.

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