"Oral bacteria in modern man are markedly less diverse than historic populations and this is thought to contribute to chronic oral and other disease in post-industrial lifestyles."
The researchers extracted DNA from tartar (calcified dental plaque) from 34 prehistoric northern European human skeletons, and traced changes in the nature of oral bacteria from the last hunter-gatherers, through the first farmers to the Bronze Age and Medieval times.
"Dental plaque represents the only easily accessible source of preserved human bacteria," says lead author Dr Christina Adler, who conducted the research while a PhD student at the University of Adelaide, now at the University of Sydney.
"Genetic analysis of plaque can create a powerful new record of dietary impacts, health changes and oral pathogen genomic evolution, deep into the past."
Professor Cooper says: "The composition of oral bacteria changed markedly with the introduction of farming, and again around 150 years ago. With the introduction of processed sugar and flour in the Industrial Revolution, we can see a dramatically decreased diversity in our oral bacteria, allowing domination by caries-causing strains. The modern mouth basically exists in a permanent disease state."