Layers of dental tartar
Bacteria in the teeth tell us a lot about nutrition and disease in our ancestors. It also tells us more about the immune system. This provides clues for treating modern diseases and allergies. For a long time archaeologists were irritated by tartar on the teeth of excavated skulls. They thought that it prevented the study of the actual tooth. In addition, tartar looked really ugly. Museums therefore scraped it off of skeletons’ teeth so that they would look more pleasing in the collection. ‘A great pity,’ says PhD candidate Kirsten Ziesemer. ‘Tartar is actually a treasure trove of information.’
The body is full of microbiomes, the collective name for the bacteria on and in the body. They are found on the skin, in the gut and in the mouth. The microbes in our microbiome are involved in everyday bodily functions, such as the digestion of food, as well as in the immune system. It was discovered in 2010 that the oral microbiome can be found in fossilised tartar. Before that microbiomes were only researched in mummies and coprolites, fossilised faeces. Neither category was found that often in archaeology. Teeth, however, are well preserved in the ground, better than bones or other human matter.
The research into tartar is still in its infancy. It provides an insight into the development of diseases of the past, into the development of bacteria over time, into the immune system and into antibiotic resistance. Research into the immune system is also relevant to modern medicine, because it provides a lot of information about the development of the immune system and the reaction of the body to disease, food and medication. For instance, recent research identified 25 of the 43 proteins that belong to the immune system. Scientists have also discovered that if the microbiome becomes unbalanced, you can become ill. Diabetes type II, bowel cancer and even gum disease have a clear link with a disruption in the microbiome (read more about this in the research dossier ‘Immunity, Infection and Tolerance’).
Furthermore, modern medicine is increasingly moving towards the personalised administration of medication. Microbiomes are just as personal as a fingerprint. If you can determine a person’s microbiome population, you can develop medication that works effectively. Archaeological research into microbiomes is important in order to gain more insight into the relationship between people, microbes and diseases and their development over time. It helps doctors develop personalised medication.
Treasure trove of information
Tartar is a treasure trove of information that can be used to reconstruct people’s nutritional patterns. Small remains of meat and pollen are stuck in it, and can be seen through a microscope. Recent research has shown that DNA material also sticks to the teeth. Everything that lives has DNA: plants, animals and people. If you study the DNA in dental tartar, you can reconstruct the nutritional pattern of our distant ancestors. Proteins are also stored in plaque. The research into milk proteins is particularly interesting. We know that the human body was not designed to tolerate cow’s milk, but that humans can tolerate it now. Researchers are trying to pinpoint the turning point in milk consumption. This research can provide direct evidence of the consumption of milk. Previously it was only possible to find indirect evidence of milk consumption, for example, by examining shards for remains of milk.
‘We have only been studying dental tartar with molecular techniques since 2010. We are now still investigating other possibilities that this research offers,’ says Ziesemer. ‘Tartar builds up in thin layers, for example. These layers can be viewed through a microscope. The deepest layer is the oldest and the external one the youngest. If you could study each layer of tartar, you could examine whether people ate different food as children than as adults. This research is not yet possible, because each layer of tartar is rough. It is really important to remove each layer precisely, because otherwise bacteria from different periods mix with each other.’
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