The first farmers weakened their immunity to survive


Ancient people lived by hunting and gathering for quite a long time, until they came up with farming, that is, specially growing plants and raising livestock. This transition is called the Neolithic Revolution, and it is believed that it began no earlier than 10,000 BC. Of course, everything did not happen all at once and not everywhere, plants and animals had to be domesticated and tamed, and somewhere the Neolithic revolution began earlier, somewhere later.

But besides domestication and domestication, ancient people had to face medical problems. Farmers and pastoralists began to live in one place for a long time, and they lived in large communities. There were cattle nearby. One can imagine what kind of outbreaks of infectious diseases began then, which were greatly facilitated by the crowding of a large number of people and dirt. Farmers and pastoralists were eventually saved by the fact that their immunity was rebuilt so as not to react too violently to infections.

When a bacterium or virus gets to us, our cells begin to exchange molecular signals, among which proteins, cytokines, play an important role. Infected cells and immune cells use cytokines to regulate the strength of the protective action. One of these protective actions is inflammation, accompanied by fever, edema, apathy, etc. Too much inflammation damages the body itself, its healthy cells and tissues. At the same time, the strength of the inflammation does not necessarily correspond to the severity of the threat – it may be that the immune system is simply hypersensitive and begins to fight the infection with all its strength, even if the infection is minor. And then you already have to be afraid not so much of the infection as of your own immune system (as happens, for example, with the coronavirus infection COVID-19, in which they try to weaken the immune response to the virus so that the immune system does not kill the patient).

The immune response depends on genes that vary from person to person. By comparing the DNA sequence of such genes with the level of inflammatory immune proteins in specific people, it is possible to understand which features in genetics correspond to overly sensitive immunity. Moreover, by comparing “DNA of more or less severe inflammation” and “DNA of more or less weak inflammation”, one can understand how the DNA of especially strong inflammation should look like. The researchers at the University of Nijmegen did just that: first, they analyzed the genetics and state of immunity in more than five hundred modern people, and then analyzed DNA from several hundred human remains ranging in age from 45 thousand to 2 thousand years. According to the immune-genetic scale, compiled on the material of modern people, it was possible to understand how things were with the reaction to infection in ancient people.

In an article in eLife It is said that those who lived after the Agricultural Revolution should have had lower levels of inflammatory proteins than older hunter-gatherers. That is, the immunity of farmers and pastoralists treated infections more calmly and allowed people to transfer the disease relatively easily. (It would be more correct to say that after the Neolithic revolution, people whose immunity did not overheat excessively in response to infection predominantly survived among people.) That is, pastoralists and farmers survived thanks to weakened immunity – weakened in comparison with hunter-gatherers.

But the immune system was weakening only in one aspect. If we are talking about local injuries, infections and inflammations, then just after the Neolithic revolution, everything intensified. Everything was more complicated: among hunter-gatherers, inflammation reacted strongly to a general infection and weakly to a local or local infection, while for pastoralists and farmers everything was the other way around, they tolerated some kind of flu of that time more easily, but scratches and abrasions should have hurt and become inflamed. they are stronger. And if the same SARS-CoV-2 coronavirus came to hunters and gatherers, there would be much, much more victims among them.

At the same time, as the portal writes ScienceSome experts believe that the results of the study should be treated with some caution. In the course of evolution, not only our immunity has changed, the pathogens that attack us have also changed. The bacteria and viruses that infected Neolithic farmers and hunters were slightly different from those that infect us today. Accordingly, inflammation in ancient people could develop with some features that are now hardly possible to recognize.


Source: Автономная некоммерческая организация "Редакция журнала «Наука и жизнь»" by www.nkj.ru.

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