Jeremy Taylor: medicine evolves and we get sick more often Bashny.Net

A recent study showed that the mortality difference between the modern inhabitants of the developed countries and the primitive hunter-gatherers than between hunter-sobiratelyamii wild chimpanzees.

These significant changes have mainly been achieved in just the last four generations, despite the fact that in the world in total there were about 8 thousand generations. But this optimistic statistics hide a puzzling and anxiety fact: today we are witnessing not decrease, but rather increased incidence

. We publish a chapter of the book of scientific journalist Jeremy Taylor's "Health on the Darwin: Why do we get sick and how this relates to evolution," which will be released by the publishing house "Alpina Publisher" in late summer

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Evolution is not interested in our health, happiness and longevity. Speaking Darwinian terms, it is only interested in maximizing reproductive success of individuals. This means that it promotes just such changes in living organisms, which allows them to adapt to environmental change and multiply.

If a certain genetic variation in certain members of the species ensures their reproductive advantage, the genes responsible for it to spread within the population. In other words, the evolution of genes concerned with immortality, but not immortal bodies. If she allows individuals to survive beyond reproductive age, it leaves them with only such qualities and abilities that increase the chances of survival of the genes transferred their children and grandchildren.

Evolution does not develop preliminary designs and plans, it can not look into the future, to see the true cause of the problem and find the perfect solution to fix the problem. In other words, when any change in environmental conditions requires a corresponding change in the structure or function of the body, evolution does not attempt to solve the problem of the survival of successful representatives of this type by fundamental improvements "project" and is looking for the fastest and easiest solution.

Of all autoimmune diseases diabetes type 1 (and all earlier diagnosis) is rapidly becoming a major scourge of the current hygiene-obsessed Western world. It is projected that the incidence rate among European children aged up to five years for the next decade is expected to double.

A sad record here is Finland with the highest percentage of diabetes type 1 in the world. In an attempt to clarify the reasons for this situation Mikael Knip and his colleagues at the University of Helsinki conducted a large-scale study to determine the role played by genetic, and some - the external factors in the development of this serious disease in which the immune system attacks the pancreatic beta cells, responsible for insulin production, which results in chronically high levels of blood sugar.

Although insulin therapy to stabilize the situation and eliminate the threat of life, many patients eventually develop kidney failure and blindness.

Intestinal microflora weighs a lot more than our brain or liver

Karelia - the territory of the north of Europe, where traditionally live Karelian nation. This area is divided into two parts: one in Finland and the other during the Second World War, it was annexed to Russia. Thus, since there is a Finnish and Russian Karelia.

Despite the fact that Russian and Finnish Karelia have the same genetic profile, including the same predisposition to diabetes, their socio-ekonomicheskoepolozhenie and health differ significantly. According to Knip, one of the harshest exists on the border between the Russian and Finnish Karelia, since GNP ahead of the first of the last eight times the world's standard of living drops.

This is even more than the difference between Mexico and the United States. Nevertheless, the prevalence of diabetes type 1, as well as many other autoimmune diseases on the Finnish side is much higher. Among the Finnish Karelian diabetes occurs six times more common celiac disease - five times more often, autoimmune thyroid diseases - up to six times more likely, and there is a higher incidence of various allergies than among Russian Karelian

. Knip was able to cooperate with the Russian side and to collect medical data, stool samples, blood samples and swabs from the skin and nose in several thousand children on both sides of the border. The researchers found that in 12 years of Russian Karelia are subjected to a higher microbial load and are more diverse in its composition colonies of microbes in the gut: better represented beneficial species of bacteria, which play a major role in protecting and maintaining the state of the intestine

. The researchers also found biochemical evidence of a more precise work of the immune system. In addition, although vitamin D deficiency is often cited as an important factor for diabetes type 1, the researchers found in the Estonian and Russian sides of the lower levels of vitamin D, than Finnish. Roughly speaking, Russian Karelia are poorer than their Finnish counterparts, but in terms of immune diseases are much healthier.

Health Darwinian why medicine is evolving, and we get sick more often
Can early exposure to a wide range of bacteria, fungi and helminths (which in the past attacked children from birth) to act in the same way as children's vaccinations - such as the triple vaccine against measles, rubella and mumps - that is, to stimulate immunity

The hygiene hypothesis in its original version, states that the way it is. This hypothesis was first introduced in the XIX century in the context of the study of allergies. In 1873, Charles Harrison Blackley said that hay fever or hay fever, caused by an allergic reaction to pollen, it is extremely rare for farmers. A little later, the 1980s, David Streken from St George Hospital in London has set in, that the presence in a family of several older brothers and sisters is also associated with a lower risk of developing hay fever.

He suggested that allergy development of younger children to protect the so-called "dirty brother syndrome", that is, a large number of postnatal infections in large families. Thus, the hypothesis Strekena stated that as a result of such early infectious attacks children acquire immunity to these diseases (in the same way as it happens with child vaccinations) and that our almost pathological obsession with hygiene deprives our immune system is so important incentive. Meanwhile, it was found a number of significant evidence that there may exist much deeper relationship in the past ten years.

About a week after the birth of the child initially sterile intestine populated colony of microorganisms, there are up to 90 trillion bacteria. Here are some amazing facts: total number of bacteria in our intestines on the order exceeds the total number of cells in our body; All intestinal flora weighs a lot more than our brain or the liver, and the total number of bacterial genes into a hundred times greater than the number of genes in the human genome.

These microbes - not tourists and locals in our body. Although scientists have long recognized that most of the microbiota is harmless and even helpful, it was thought that we allow them to take away the nutrients that pass through our intestines, and provide them with a warm and oxygen-free habitat. In return, they provide us with their digestion of waste, such as vitamins B, H and the K, which we can not produce themselves, and cleave sugar and fatty acids such as butyrate, promoting metabolism.

But now it has become clear that our relations with "old friends" go far beyond this symbiosis. We have evolved in such a close interdependence with our microbiota that share our genomes it is no longer meaningful. Now scientists say metagenome, which is a collection of human genomes and its microbiota - superorganism in which we humans are the junior partners, and without which we can not exist

. The researchers asked two fundamental related questions. Firstly, how our body differentiates the "old friends" (commensal bacteria, fungi and intestinal helminths) from dangerous pathogens, to live peacefully with the first and second attack? Secondly, what happens to human health when these "old friends" weaken or disappear completely?

Answers to these questions allow us to better understand the processes occurring in our body, and get a more accurate picture of the work of our immune system, which in turn will help develop a new generation of pharmacological agents to help overcome large-scale epidemic of allergic and autoimmune diseases, tormenting today the developed countries.

It has one general principle. The human immune system had to learn to be tolerant to a broad range of microbes and fungi that had been present in the food and the water - and thus infect humans - for millions of years. The same applies to the helminths, as soon as they settled in the body, get rid of them was almost impossible, so the immune attack on them would bring disproportionately more harm than good

. For example, the persistent attempts of the immune system to destroy the larvae of filamentous helminths Brugia malayi can lead to the development of inflammatory seals in the walls of the lymphatic vessels and clogging that causes elephantiasis. Millennium coexistence led to the development of the state of interdependence.

This synanthrope had to learn to manipulate our immune system so as to be able to easily exist within us, without being subjected to constant attacks, and our immune system had to learn not to react too heavily on these long-term residents, not to cause harm to the body.

This means that in a certain sense, we gave control of our own immune system dwells within us microbiota. But there is another danger: the fact that such a scheme is immune regulation works well in the presence of our rich assortment of gut friendly bacteria, fungi and helminths, but as soon as "old friends" disappear, this scheme fails quickly
<. br> Our immune system is strong, accustomed to operating in the presence of relatively harmless endoparasites, it gets out of control and loses brakes, causing chronic inflammation that is the cause of today's epidemic of allergic and autoimmune diseases.

Health Darwinian why medicine is evolving, and we get sick more often
How can the bacteria in our gut communicate with our brain, and vice versa? What is the communication channel between them? Recently, researchers Emeral Meyer and Kirsten Tillish conducted an interesting study they sought to determine the effect of probiotic bacteria on mood and brain activity of people

. The study was conducted in healthy female volunteers group using functional MRI. One group of women taking probiotic fermented yogurt drink twice a day for four weeks, the second group was a control.

Women were examined using functional MRI before and after the course of therapy: at rest and while viewing images of individuals expressing various emotions. The researchers were able to identify the most communicative link between the gut and the brain: it turned out to be a bundle of nerve fibers in the brain stem, known as the solitary tract nucleus (or nucleus of the solitary tract)

. This nucleus receives signals from the vagus nerve, which innervates the gut, and in turn, activates the neural circuits that pass through the higher brain centers, including the amygdala (responsible for fear and other emotions), insula share and the anterior cingulate cortex, that is all those regions involved in emotional information processing.

In volunteers who took the probiotic yoghurt, reduced activity was observed in the neural circuits of the data, indicating lower levels of arousal and anxiety. These women showed a calmer emotional reactions. And although the results of this study should be interpreted with caution, it is reasonable to assume that the probiotic bacteria in the gut are capable of sending signals to the brain through the medium of the vagus nerve, literally allowing us to feel instinctively.

The current epidemic of diabetes type 1, obesity, inflammatory bowel diseases, allergies and asthma to a large extent caused by our own

In a recently published article, Joe Elcock, Carlo Meili and Athena Aktipis cause a lot of evidence that live in our gut bacteria can influence our food, creating a craving for those products that give them a competitive advantage in the colon. At the same time they cause a state of dissatisfaction and anxiety, as we do not eat them with necessary products, such as chocolate, which not only gives pleasure through stimulation of reward centers in our brains, but also satisfies the nutritional requirements of bacteria.

A vagus nerve intestinal bacteria manipulate our behavior. This gives us a fantastic opportunity - by changing species composition of intestinal microflora to change our eating habits and even prevent obesity

. Perhaps we are entering an era where microbiology and immunology (and, in particular, the hypothesis of "old friends") will have a real impact on public health policy.

So, microbiologist Martin Blaser expresses its deep concern about the excessive use of antibiotics. We all know about the dangers of spreading multidrug resistance to antibiotics today, which leads to the appearance of supermikrobov, almost non-destruction.

But the standard practice of the treatment of a broad spectrum antibiotics also destroy the friendly and beneficial commensal bacteria in the body, leading to disastrous consequences. For 18 years, Blazer says American children are on average ten to twenty courses of antibiotics, which kill not only enemies, but also

«old friends." In some cases, the intestinal microbiota was never recovered, so the current epidemic of diabetes type 1, obesity, inflammatory bowel diseases, allergies and asthma are largely caused by ourselves. Thus, the risk of developing inflammatory bowel disease increases with the number of courses of antibiotics.

Even worse is that antibiotics are used on an industrial scale for growing farm animals - only in order to stimulate rapid weight gain. Antibiotics are appointed by the standard almost half of pregnant women in the United States, as well as the children get intestinal microflora from their mothers, each generation begins life with a poor legacy in the form of friendly bacteria than the previous one.