An international team, led by the University of Adelaide's Centre for Ancient DNA (ACAD), published research based on the examination of DNA preserved in calcified bacteria on the teeth of ancient human skeletons in the Feb. 17, 2013, issue of Nature Genetics that is the first to quantify the rise of dental problems in humans as a result of changing diet.
The study looked at the last 7500 years of human life and revealed 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.
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. The scientists compared the bacteria in the ancient people’s mouths with the bacteria found in present day humans.
The scientists conclude that "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 postindustrial lifestyles."
The decrease in oral bacteria began with the introduction of farming and dramatically decreased with the introduction of processed sugar and flour around 150 years ago.