The DNA of the microbes conserved on the fossilised teeth of our ancestors – specifically the ones from the bacteria calcified in their tartar or dental calculus – contains a lot of information about the microbiota inhabiting the guts of the civilisations that lived thousands of years ago. With this finding, we can now discover the effects of dietary changes on human health from the Stone Age to our time, according to scientists attending the “Ancient DNA: the first three decades” meeting held at the Royal Society in London in November 2013.
Dr Christina Warinner, an American anthropologist from the University of Oklahoma and co-author of the study, is determined to extract information on how the microbiota changes during an individual’s lifetime by dissecting the very thin layers of calculus built up on their teeth during their lives. It will not be an easy task, given that the samples include a lot of DNA. “In some cases, the concentration of DNA from microbes in dental calculus is as high as in a living human liver,” says Warinner. Great care will also need to be taken to avoid contaminating the samples. Researchers will therefore also study the inner part of the tooth, which indicates the microbial composition of the soil, water, etc., and compare that with the composition of the calculus. “If the similarity is strong, it will be a good sign,” explains Warinner.