The new analysis pointed to bacteria that were common in pre-industrial societies and those that only appeared in modern humans.
The intestinal microflora plays a vital role in digestion and the functioning of the whole organism, even affecting mood. The composition of these bacteria is closely related to nutrition and allows you to find out how the diet of people has changed throughout the development of society. This analysis was recently conducted by an international team of scientists led by Harvard School of Medicine professor Aleksandar Kostic. Their article was published in the journal Nature.
The authors used fecal samples from dry caves in the southern United States and Mexico, dating back one to two thousand years. After analyzing the DNA extracted from them, it was possible to determine the presence of about 500 species of bacteria, almost 40 percent of which had not previously been found in the intestinal microflora of humans. Such a variety is practically not found today.
With the spread of agriculture and the dominance of the same type of cereals, the help of many different bacteria in digestion is no longer required, and modern people get by with a more limited set of symbiont microbes. Scientists have demonstrated this by comparing the microflora of the ancient inhabitants of America with the microflora of almost 800 current residents of the United States and Western Europe, as well as representatives of relatively isolated communities in Tanzania, Mexico and Peru.
In particular, the bacterium Treponema succinifaciens was found in both ancient people and modern isolated tribes, but not in any of the studied inhabitants of developed urbanized societies. It is also curious that the bacteria of the "ancient microflora" have a wider representation of the genes of transposases - enzymes necessary for the exchange of DNA. Apparently, this allowed them to quickly adapt to changing environmental conditions and the variety of food supplied.
At the same time, such samples lacked some microbes characteristic of the "modern microflora". So, Akkermansia muciniphila was not identified there, which is often found today and is considered a companion to a diet rich in meat and sweet foods. According to some reports, these microbes may play a role in the development of obesity, diabetes and chronic inflammation.