Ancient Teeth Reveal Impact of Diet Change

Ancient Teeth Reveal Impact of Diet Change

In comparison to earlier humans, it seems reasonable to assume that the oral bacterial composition of modern people is healthier than our forbearers. Yet, an international team of researchers who collaborated on a study headed by the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) might beg to differ. Results from the 17-year project show that the oral bacterial levels of subjects from prehistoric through medieval times were, in fact, much more balanced than those of modern humans. The researchers were also able to identify when the diversity of oral bacterial levels began to decline.

Led by Alan Cooper, PhD, director of ACAD, the team extracted DNA from the tartar of 34 northern European human skeletons from the distant past and studied changes in the nature of bacterial strains over time. The specimens came from hunter-gatherers in Poland, early central European farmers, and peoples from the late Neolithic period, Bronze Age, and medieval times. The researchers found that the oral bacteria in prehistoric and early historic populations was far more diverse than those found in modern man—and a loss of diversity of bacteria is almost always associated with disease. This has made contemporary humans more vulnerable to oral disease. The investigation, published in the journal Nature Genetics, has been described as the first detailed genetic record of the evolution of human microbiota.

“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 during the Industrial Revolution, we can see a dramatically decreased diversity in our oral bacteria, allowing domination by caries-causing strains,” explains Cooper. Since these two historical junctures, the modern mouth has basically existed in a permanent state of disease, he says. Continuing their studies, the research team plans to expand by going to new locations and including additional species, such as Neanderthals.