Evidence of tooth decay-causing bacteria found in 4,000-year-old human molars in Limerick

An example of a tooth specimen prior to ancient DNA sampling (Lara Cassidy/Trinity College Dublin/PA)

Scientists have found evidence of bacteria that cause tooth decay and gum disease in 4,000-year-old human molars.

Trapped within the dental remains that were unearthed from a limestone cave in County Limerick, the researchers found an “unprecedented quantity” of the DNA of streptococcus mutans, a type of bacteria in the human mouth responsible for cavities.