Scientists Extract Genetic Secrets from 4 000-year-old Teeth to Illuminate the Impact of Changing Human Diets over the Centuries
Published:18 Jun.2024 Source:Trinity College Dublin
Researchers at Trinity College Dublin have recovered remarkably preserved microbiomes from two teeth dating back 4 000 years, found in an Irish limestone cave. The researches identified several bacteria linked to gum disease and provided the first high-quality ancient genome of Streptococcus mutans, the major culprit behind tooth decay.
This man was at a high risk of developing cavities right before his death. The researchers also found that other streptococcal species were virtually absent from the tooth. This indicates the natural balance of the oral biofilm had been upset -- mutans had outcompeted the other streptococci leading to the pre-disease state. The two Bronze Age teeth produced highly divergent strains of Tannerella forsythia, a bacteria implicated in gum disease.
T. forsythia strains from the industrial era onwards contain many new genes that help the bacteria colonise the mouth and cause disease. S. mutans has also undergone recent lineage expansions and changes in gene content related to pathogenicity. The scientists believe this is driven by differences in the evolutionary mechanisms that shape genome diversity in these species. In effect, both these disease-causing bacteria have changed dramatically from the Bronze Age to today, but it appears that very recent cultural transitions in the industrial era have had an inordinate impact.