What our teeth tell us about our diet.
DNA from tartar (calcified dental plaque) on human teeth reveals the changes in our oral bacteria that accompanied the changes in our food supply over the past 7500 years. ‘Dental plaque represents the only easily accessible source of preserved human bacteria,’ says lead author Dr Christina Adler. ‘Genetic analysis of plaque can create a powerful new record of dietary impacts, health changes and oral pathogen genomic evolution, deep into the past.’
The international team of researchers led by the University of Adelaide's ACAD (Australian Centre for Ancient DNA) extracted DNA from tartar 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. ‘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. ‘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 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 [starch] 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.’
– Nature Genetics.
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The Australian Centre for Ancient DNA (ACAD), which was established by Prof Alan Cooper and opened in 2006, provides the specialist equipment and ultra-sterile working environment required for the study of minute traces of preserved genetic material. ACAD has been designed to provide a centre for evolutionary research in the Southern Hemisphere, particularly the impacts and timing of environmental change (eg climate, humans) on animals, plants and microbes by measuring the genetic records preserved in bones, teeth, leaves and seeds, feces, and other remains from caves, museums and even sediment cores from lakes, rivers and marine sites.