This is a surprising and unexpected study, showing that the most interesting results can arise from the unlikeliest areas. (New Scientist, 19th April 2014).
Not long ago, when archaeologist found an interesting skeleton, they would clean the plaque off the teeth to examine them properly, just like your dentist does, and like we try to do with toothpaste and floss. Now it has been discovered that plaque is the calcified remains of microbes in the mouth, and the DNA can now be extracted from these calcified microbes, and identified, even from very old skeletons. This is especially interesting as it is becoming clearer that we co-evolve with our microbes, so we can directly correlate the effect of diet, microbe flora in the mouth, and tooth condition. And, we can also now do this for all groups of people on earth now, from the last remaining hunter-gatherers to the fast-food eaters in the cities. We can get an idea of each of their microbiomes – the microbes that they co-exist with in their mouth and digestive systems. This is part of the developing idea that the bacteria and microbes inside us and on us are not necessarily a bad thing – many of them provide us with useful services involved in protecting the skin, and helping with the digestion and metabolism of foods, etc.
Picking out one of the main points of interest from the article, Streptococcus mutans is one of the main indicators of the modern diet and one of the main causes of tooth decay, and it seems to have only got involved in our mouths and digestive systems with the advent of refined sugars in the industrial revolution. The results show that S. mutans is almost unknown in both in Mesolithic and Neolithic times, and also in modern hunter-gatherers, and tooth decay is almost unknown in these groups.