Plaque in ancient teeth preserved by microbes
SUMMARY: In a new study of four medieval skeletons, archeologists discovered that the bacteria on teeth may yield more genetic value than bones.
Posted: May 14, 2014
A tooth time capsule has been discovered in the jaws of four medieval skeletons. If you thought sleeping for one night causes bad morning breath, consider what 1000 years of slumber could do.
Scientists from the University of Oklahoma found DNA of millions of tiny organisms living in the ancient dental plaque lodged in four skeletons from a Medieval convent in Dalheim, Germany. The microbes perfectly preserved their teeth.
"This is a game changer," Christina Warinner, a molecular anthropologist at the University of Oklahoma and the lead author of the study, told the Los Angeles Times.
The findings, published in the journal Nature Genetics, could provide clues to what our ancestors ate and what tooth disease plagued their oral health.
Throughout most of the archeological timeline, researchers had overlooked calcified dental plaque, often removing it from skeletons in the process of cleaning. But now there has been a shift, a new understanding that this plaque is a treasure trove of information.
"People are realizing that you have this rich bacterial community living on the surface of your teeth, and if your gums are bleeding you have an open vascular network right next door to a microbial community," Collins told the Times. "There is so much information there. The challenge is how to access it."
After scraping the mineralized plaque off the teeth of the four skeletons and treating the samples with various chemicals, Warinner put them through a machine that divides the cell debris from DNA. The results were shocking, she said.
Normally, the DNA from bones is so damaged that it is hard to distill much information from it. Yet, this dental calculus produced 100 to 1,000 times more DNA fragments than have been recovered from a bone previously.
Matthew Collins, co-author on the paper and researcher from the University of York, referred to it as a "microbial Pompeii."
Calcified plaque is the yellow, rough coating that gathers on teeth if patients do not take care of their mouth. While dentists in the modern world scrape plaque off teeth as part of regular dental cleanings, a millennium ago the tartar could grow as thick as the tooth itself, the scientists said.
Bacteria associated with gum disease have not changed much in 1,000 years despite shifts in diet and dental hygiene, Warinner and an international team of colleagues determined. They also discovered bits of plant DNA in the plaque, further evidence of the ancient diet.
Researchers said that this discovery is just the tip of the iceberg.
"Everything was there in an incredible level of detail and it was frozen in time," said Collins.