The process
To find out, she scraped the mineralized plaque off the teeth of four skeletons from a medieval convent in Dalheim, Germany, and after treating the samples with various chemicals and enzymes, she put them through a machine that separates cell debris from DNA.
The result, she said, was thrilling.
"When you get DNA from bones it is so damaged and there is so little of it left, " she said. "When we analyzed the dental calculus we got 100 to 1,000 times more DNA fragments than we would have from a bone."
From those DNA fragments Warinner and an international team of colleagues determined that the bacteria associated with human periodontal disease have not changed much in 1,000 years even as dental hygiene and diet have. They also found that ancient oral bacteria had a gene that could allow it to resist low-level antibiotics, just as some of our oral bacteria has today. And they found bits of plant DNA in the plaque, which provides direct evidence of the ancient diet.
But these results are just scratching the surface of what scientists can learn from ancient plaque.
Endless possibilities for discovery
Anne Stone, a molecular anthropologist at Arizona State University who was not involved in the study, said the findings were significant.
"What is exciting is it looks like the way calculus forms protects the DNA -- almost like it is sealed in concrete -- so it is more protected from the environment," she said. "People who study respiratory pathogens will be interested in this study, and people who study how periodontal disease has changed over time."
Warinner notes that every known human population has had dental plaque problems, so this technique could be used to learn more about people from a wide range of time periods.
mms://203.69.69.81/studio/20140814adab262a3292462fc5383564370bd23d5902fefd37ea6eabc8c28094e82e0bd4665.wma
No comments:
Post a Comment