4,000 years ago, man lived in County Limerick at 'high risk' of tooth decay – Irish Times

Scientists examine the teeth of a man who lived in what is now Colorado more than 4,000 years ago limerick It was determined that the patient was at high risk of developing tooth decay just before his death.

Scientists have studied the remains of two teeth found in a limestone cave and have successfully provided the first high-quality ancient genome of Streptococcus mutans, the main culprit behind tooth decay.

They also identified some bacteria associated with periodontal disease.

This study was conducted by scientists. trinity college dublin The study, a collaboration between archaeologists from the Atlantic Institute of Technology and the University of Edinburgh, is published Wednesday in the journal Molecular Biology and Evolution.

Researchers say a surprisingly preserved 'microbiome' from two teeth reveals major changes in the oral microenvironment from the Bronze Age to today, and how humans have changed over the centuries. He said that this shows the influence of dietary habits.

The teeth were part of a large skeletal assemblage excavated from Killer Cave by the late Peter Woodman of Cork University. Other teeth in the cave showed advanced cavities, but none of the extracted teeth showed any cavities.

However, a single tooth produced an unprecedented amount of Streptococcus mutans DNA.

“We were very surprised to find such large numbers of S. mutans in this 4,000-year-old tooth,” said study lead author Dr. Lara Cassidy, assistant professor in the Department of Genetics and Microbiology at Trinity University. Told.

“This is a very unusual finding and suggests that this man was at high risk for tooth decay shortly before his death.”

The researchers also found that the teeth were virtually free of other streptococcal species. This indicates that the natural balance of the oral biofilm was disrupted. Streptococcus mutans competed with other streptococci, resulting in a pre-symptomatic state.

The researchers also found evidence supporting the “disappearing microbiome” hypothesis, which states that modern microbiomes are less diverse than the microbiomes of our ancestors. This is a cause for concern because biodiversity loss can affect human health.

The two Bronze Age teeth produced highly diverse strains of Tannerella forsythia, a bacterium associated with periodontal disease.

“Despite modern samples originating from Europe, Japan, and the United States, these strains from a single ancient mouth are genetically more distinct from each other than any modern strains in our dataset. ,” said Isolt Jackson, a doctoral candidate at Trinity. He is the first author of this study. “This represents a huge loss of diversity, and we need to understand this issue better.”

Few complete genomes of oral bacteria have been recovered from before the Middle Ages. By characterizing prehistoric diversity, the authors were able to uncover significant changes in the oral microenvironment that have occurred since then.

Dr Cassidy added: “Over the past 750 years, a single lineage of forsythia has become dominant around the world. This is a clear sign of natural selection, with some strains having a genetic advantage over others. Its frequency increases rapidly because of the presence of bacteria in the mouth. Post-industrial forsythia strains contain many new genes that help bacteria colonize the mouth and cause disease.

“S. mutans has also recently experienced lineage expansion and changes in gene content associated with virulence. These are consistent with high human consumption of sugar, but modern S. mutans populations remains more diverse, indicating a deep split in the S. mutans evolutionary tree that predates the killer genome.”

In fact, both of these pathogens have changed dramatically from the Bronze Age to today, but very recent cultural changes since the industrial era appear to have had an immense impact.

This research was funded by the Wellcome Trust Institutional Strategic Support Fund and the Irish Research Council Laureate Award, and supported by the Science Foundation Ireland Center for Research Training in Genomics Data Science.