(ORDO NEWS) — The authors of a new study found out how the transition from hunting and gathering to crop production and pastoralism has changed the human microbiome.
A group of Italian scientists in which they presented the results of a study of ancient DNA from human tartar from the Upper Paleolithic to the Eneolithic.
The authors of the work showed how and why the microbiome of the human mouth has changed over 30 thousand years.
The set of bacteria living in the oral cavity of people directly depends on nutrition. Scientists usually judge the change in nutrition in ancient human communities by archaeological finds of food remains.
The authors of the new study went the other way: they isolated DNA from the tartar of 76 people who lived in roughly the same place, but separated by millennia.
The researchers hoped to find out in this way whether the oral microbiome was changing at a time when hunter-gatherer communities turned to agriculture.
To reliably separate the pre-agricultural microbiome from the subsequent ones, they took 11 samples of tartar found in the Pagliicci cave in southeastern Italy (Province of Puglia).
In the Upper Paleolithic (31-11 thousand years BC) there was a site of Cro-Magnons, the bearers of the Gravettes and Aurignacian cultures.
The remaining samples belong to the Neolithic (6200-4000 BC) and Eneolithic (3500-2200 BC). The finds of all samples were made in the same province of Apulia.
As is known from archaeological finds, agriculture on the Apennine Peninsula began precisely from those places. Approximately 6200 years BC, people from the Levant got there – and brought agriculture with them.
The Neolithic in this area is usually divided into four main cultural phases: the early period (corresponding to the Cardium Pottery culture brought from the Levant ), the middle period (the Passo di Corvo culture), the transitional period (the Serra d’Alto culture) and the late period (the Diana culture).
The change of archaeological cultures in one place usually indicates a change in the way of life of the community – or the displacement of the previous inhabitants.
The authors of the work believe that in the case of the Neolithic population of Puglia, this is not about displacement.
It turned out that at about the same time that archaeological cultures are changing, the microbiome of people’s oral cavities is also changing.
The first major difference from the Upper Paleolithic samples dates back to the early Neolithic: apparently, then people began to consume more starchy plants.
Scientists associated the next change in the microbiome with the use of milk, and therefore with cattle breeding (this is also confirmed by archaeological finds in time).
We have already talked about the fact that people began to drink milk even when they could not fully digest it.
The next major change in the composition of bacteria in the human mouth occurs already in the Late Neolithic.
The authors of the work believe that during this period people began to actively use fermented foods: they fermented vegetables and milk so that they could be stored longer.
This also coincides with the results of archaeologists: traces of fermented food are found on ceramics of that period, in addition, there are finds of dishes in which vegetables were fermented directly, and slingshots used to churn butter.
Usually, the expansion of the diet is considered a sign of the development of society and an absolute boon for man.
But not everything is so simple, say the authors of the new work. You have to pay with your own health to improve the standard of living.
In general, the bacteria living in the oral cavity are the first to break down the food that enters the body. And it seems that they are quite harmless and even useful.
But from tartar from samples dating back to the third and fourth Neolithic periods, the researchers isolated the DNA of the bacterium Porphyromonas gingivalis .
It is an anaerobic bacterium that causes gum disease, particularly periodontal disease. Recently, the presence of P. gingivalis has also been associated with several extraoral diseases such as cardiovascular disease, diabetes, and Alzheimer’s disease.
It appears to have a direct effect on the microbial composition of the host gut.
Upper Paleolithic people have no evidence of P. gingivalis in tartar, and in general their teeth were in much better condition at the time of death than even Neolithic hunter-gatherers who were just beginning to master agriculture. In representatives of the early and middle Neolithic, this bacterium is already present.
But their descendants from the late Neolithic have many traces of the presence of P. gingivalis . Improving the diet brought them caries and periodontal disease.
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