Ancient Teeth Bacteria Reveal Health Consequences of Modern Diet

You are what you eat--and your teeth may be suffering for it. DNA preserved in calcified bacteria on the teeth of an ancient skeleton may show the health consequences of the modern diet.

An international team, led by the University of Adelaide's Centre for Ancient DNA (ACAD), examined the DNA from the tartar that they collected from 34 prehistoric northern European human skeletons. They then traced the changes in the nature of this oral bacteria from the last hunter-gatherers to the first farmers to the Bronze Age and eventually, to the Medieval times.

It wasn't easy examining the DNA samples, though. Alan Cooper, the study leader, and his team have been working on this project for the past 17 years. While they had been able to show that tartar deposits on ancient teeth were dense masses of solid, calcified bacteria, they were unable to identify the species of these bacteria. In addition, they were unable to sufficiently control background levels of bacterial contamination until 2007, when ACAD's ultra-clean laboratories became available.

The ancient genetic record showed the negative changes that occurred in oral bacteria as ancient populations shifted to farming and later, introduced food manufacturing in the Industrial Revolution. Researchers found that over the last 7500 years, we have drastically impacted the bacteria present on our teeth. In particular, oral bacteria in the modern man are far less diverse than in historic populations. This lack of diversity could help contribute to chronic oral and other disease.

Why exactly does a lack of diversity cause these issues? They allow the mouth to be dominated by caries-causing strains, which puts the modern mouth in a permanent, disease state, according to Cooper.

"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," said Cooper in a press release.

The findings were published in Nature Genetics.