Lara Cassidy
A 4,000-year-old ancient tooth discovered in a limestone cave in Ireland has been found to be enriched with cavity-causing bacteria that are rare in the ancient genomic record.
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It has been discovered that the two teeth of a man who lived approximately 4,000 years ago were rich in bacteria that primarily cause cavities and periodontal disease. This unusual discovery could help scientists better understand how changes in human diets led to today’s tooth decay epidemic.
It was discovered during two excavations from 1993 and 1996The tooth was among several human teeth and other remains discovered in a limestone cave in County Limerick, Ireland. The two molars, taken between 2280 BC and 2140 BC, both belonged to the same person who lived during the Bronze Age. Paper published on Wednesday Published in the journal Molecular Biology and Evolution.
One tooth was surprisingly rich in Streptococcus mutans (S. mutans), an oral bacterium that causes tooth decay. This bacterium is rare in the ancient genomic record and does not preserve well, perhaps due to its propensity to produce acids in teeth that cause cavities and DNA degradation, said Lara, senior author of the paper and assistant professor in the School of Dentistry. Cassidy said. Studied Genetics at Trinity College, Dublin.
The researchers also believe that this bacteria was less commonly found in ancient teeth because the human diet contained less refined sugar and processed foods than is consumed today. Cassidy said. With the beginning of agriculture, there were major changes in dietary habits. 10,000 years agoHowever, the past few hundred years have seen a major change with the spread of sugar, she added.
Relationship between dietary changes and tooth decay
It’s unclear why the newly discovered tooth bacteria was so well preserved, but Cassidy said the cool, dry conditions of the cave were likely a factor.
Although cavities have been observed in other ancient tooth finds, S. mutans has only been found in very small quantities in a small number of older tooth-like sites. neolithic teeth Southwest France (between 3400 BC and 2900 BC) or Scandinavian Mesolithic (between 9890 and 9540 BC). According to the paper, observations of cavities in other ancient teeth became more frequent after the introduction of grain agriculture, the cultivation of grains such as wheat and barley.
By analyzing bacteria found on Bronze Age teeth and comparing them with modern samples, researchers discovered that the evolutionary tree of ancient Streptococcus mutans was more complex than originally thought. Discovered characteristics such as pathogenicity (virulence) of ancient bacteria. damage) evolved with changes in the human diet, such as the prevalence of sugar and grains, Cassidy said.
“Over the past few hundred years, we’ve seen a tremendous amount of change[in human diet]especially as it changes not only microorganisms but also the microbiome, the bacteria that naturally live in and on humans. It is important to understand how the oral microbiome and gut microbiome have similarly affected the development of certain diseases in Western and Westernized populations over the past few centuries. “It might help us understand a little bit why it’s become so prevalent among people,” she added.
Although no signs of caries were found in the Bronze Age teeth, the abundance of bacteria suggests that if this Bronze Age adult man had lived longer, his teeth would have developed quickly. Cassidy said it was suggested.
The two teeth also contained DNA evidence of T. forsythia, a bacteria involved in periodontal disease that is more commonly found in the ancient genomic record. However, researchers found two different strains of bacteria in the teeth. Only one type of bacteria is now commonly found, suggesting that ancient microbiomes were much more diverse than modern microbiomes. According to a news release, biodiversity loss is of concern because it can negatively impact human health. Trinity College, Dublin.
Several other teeth found in the cave showed signs of decay, suggesting they belonged to the same person whose remains were found separated and disarticulated from other skeletal remains. Cassidy said it’s unclear whether it belonged to other members of the community. “It’s possible that other teeth in his mouth had cavities or that other people in his community were suffering from dental disease.”
Analysis of ancient S. mutans bacteria suggests that sugar intake has made the bacteria more prevalent in recent centuries, creating a favorable habitat for the species in the human mouth, Cassidy added. Ta. Understanding the lineage of modern-day cavity-causing bacteria will further help scientists understand how changes in diet affect oral health today, she said.
Analysis of ancient Streptococcus mutans compared to modern Streptococcus mutans “reveals major changes over the past several hundred years associated with increased consumption of sugar,” and the incidence of tooth decay after refined sugar became widespread. This confirms previous research that showed an increase in Although it was available in the 19th century, Louise Humphrey saida research leader at the Center for Research in Human Evolution at the Natural History Museum, London, was not involved in the study.
“The oral microbiome influences many areas of human health and disease. …Ancient teeth reveal how the human oral microbiome (a variety of microorganisms) has evolved over time, and It helps us understand how that change impacts human health in the past and today,” Humphrey said in an email.
