Dental problems have tormented humans for ages, but the recent discovery and analysis of two 4,000-year-old teeth reveal how the bacteria populating our mouths have changed over time. The teeth, found in a limestone cave in Killuragh, County Limerick, Ireland, along with other skeletal remains, have helped researchers piece together a timeline of oral health. Their findings have been published in a new paper released in Molecular Biology and Evolution.
Although fossilized teeth and their DNA are often well-preserved and highly valued by archaeologists, it’s rare to come across full genomes from oral bacteria in teeth predating the Medieval era. As a result, it has been difficult to discern the extent of oral health throughout history, including the dietary changes that played important roles. However, the two teeth from the limestone cave — both belonging to the same Bronze Age man — have now supplied researchers with a deeper understanding of ancient oral microbiomes.
A Precursor to Cavities
The sampled teeth didn’t exhibit signs of caries (another term for tooth decay), but one had an ample amount of S. mutans, a type of bacteria that is considered the main cause of cavities. This stood out to the researchers because S. mutans is rarely observed in the ancient genomic record. Its absence could be explained by its tendency to produce acid that not only causes tooth decay but also breaks down DNA and prevents plaque from mineralizing.
