DNA preserved in calcified bacteria on the teeth of ancient human skeletons has shed light on the health consequences of the evolving diet and behaviour from the Stone Age to the modern day.
The ancient genetic record reveals the negative changes in oral bacteria brought about by the dietary shifts as humans became farmers, and later with the introduction of food manufacturing in the Industrial Revolution.
An international team, led by the University of Adelaide's Centre for Ancient DNA (ACAD) where the research was performed, has published the results in Nature Genetics today. Other team members include the Department of Archaeology at the University of Aberdeen and the Wellcome Trust Sanger Institute in Cambridge (UK).
"This is the first record of how our evolution over the last 7500 years has impacted the bacteria we carry with us, and the important health consequences," says study leader Professor Alan Cooper, ACAD Director.
"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."