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What did we eat 6,000 years ago? How did the teeth of men differ from the teeth of women in the early Middle Ages? Are contemporary malocclusions the result of evolutionary changes? Scientists from the Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz answer all these questions.

The chewing apparatus, including teeth and jaw bones, constitutes an excellent material to study microevolution. Microevolution shows the changes taking place within our species, including adaptation to environmental changes.

Teeth are a great research material because, compared to bones, they are more resistant to the effects of unfavourable environmental factors, such as temperature, drying out or being in water/waterlogging. Moreover, teeth are formed once in a lifetime and, contrary to bones, they do not rebuild themselves.

- says dr Justyna Karkus from the Department of Anthropology, Faculty of Biology and Environmental Protection. 

This knowledge is very useful, for example, in forensics, especially as both the teeth and the bite are very individualised. 

On their basis, it is easy to assess the age at death – based on the degree of abrasion of the tooth crowns, or in the case of children – the degree of formation of tooth buds. Teeth and bones also allow to obtain material, e.g. for isotope testing. In turn, based on this, we can determine the diet of the individual under study and, indirectly, also their socio-economic status.

- explains dr Karkus. 

6,000 years ago

The research of scientists from Lodz shows how the human chewing apparatus has changed in the last 6,000 years, i.e. from the Neolithic period to the modern times (19th century). 

We observe very large differences between the skeletons of people from the Neolith and those from the early Middle Ages. It should be remembered, however, that there is a very large time gap between these periods, which results from the fact that the cremation funeral rite was dominant between the Neolith and the early Middle Ages, and thus there are no complete skeletons that could be examined. 

- says dr Karkus. 

On the other hand, it is thanks to this gap that the changes that took place in the structure of the chewing apparatus are clearly visible. Additionally, during this time, the populations changed a lot in terms of culture.

In the Neolithic period, we observe a very high pressure on the chewing apparatus, caused, for example, by a hard diet, lack of crumbled food and thermal treatment, but also by the load on the teeth during work. That is using the teeth as the so-called "third hand".

- adds dr Karkus.

Malocclusion – Evolution Effect?

After introducing soft foods into the diet, for example potatoes, which took place in Poland around the 17th century, the burden on the chewing apparatus became even smaller. In biology, if an organ is not used intensively, it is reduced. Our research shows that the relieved chewing apparatus was gradually reduced, i.e. it simply got smaller and smaller.

- emphasizes dr Karkus. 

However, not all components of this apparatus decreased at the same rate. Some of them were more influenced by environmental changes, others by genes. And this is the case with teeth that are strongly determined genetically, and in turn the bones of the jaw and mandible (lower jaw) are more responsive to environmental changes. What is the conclusion?

This led to the teeth getting smaller more slowly and, in turn, the bones, more quickly. Thus, there was disharmony and the frequency of defects within the chewing apparatus increased. The research shows that we can expect more of these flaws in each subsequent generation. 

- explains dr Karkus.

Another significant change is the reduction in the number of teeth.

If we look at the third molars (popularly known as eights), in the Neolith their deficiencies were present in less than 8% of the studied individuals, in the 19th century it was already 50%. This process is due to the fact that in the course of microevolution it is easier to reduce the number of teeth rather than their size. So we can say that if someone does not have eighths, then they are evolutionarily advanced.

- says the researcher.

It's not just the case of eights. For example, lateral incisors in the upper dental arch are also disappearing more and more often.

These teeth have a reduced size of the crown or may not be there at all. And from the point of view of microevolution, there is nothing extraordinary about it. 

- says dr Karkus.

If these trends continue, there will be more and more people without a full set of teeth in each successive generation.

Female teeth and male teeth

Your work can also leave marks on your teeth.

Today, tailors, shoemakers, confectioners and bakers will also have changes in the teeth characteristic of their profession. In the case of the first two professions, these will be grooves on the incisal edge of the teeth, caused by holding needles or threads with the teeth. Confectioners and bakers, in turn, will have cavities because the sugar that floats in the air will stick to the teeth and lead to their destruction. Similar changes can also be found in representatives of ancient populations. Based on the teeth, it is possible to draw conclusions regarding the work performed with their use, but also regarding the gender differences in this area. Our research has shown that in the analysed group from the early Middle Ages (11th-13th century) women were more likely to experience defects in the horizontal position of the front teeth. It was probably influenced by the use of teeth during work. Historical sources indicate that at that time, women frequently engaged in, for example, spinning. In addition, these women also show degenerative changes in the temporomandibular joint, i.e. the one that works intensively when using the chewing apparatus.

- explains dr Karkus. 

Source: Faculty of Biology and Environmental Protection, University of Lodz