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Stress and lack of maternal care in early life are reflected not only on the children themselves, but also on subsequent generations. Nikolay Kukushkin parses this and other cases when acquired traits, contrary to classical notions of genetics, may be inherited. Rat petting if you think that State Duma deputies have been particularly active in recent years Concerned with the mental health of children, far from scientific side of the issue, then you underestimate them. Research by scientists from Tufts University in the USA shows how important it is to isolate children from stress and provide maternal care. Rats, grown in social conflict and preoccupied extraneous problems of the mother, in adulthood differ serious endocrine changes, increased aggressiveness and most interestingly, a weakened maternal instinct. And if on the guard of the moral side of the issue in our country are vigilant lawmakers, we are most interested in genetics. Lack of care in one generation leads to its subsequent lack of the following: what is not a form of heredity? ABOUT futility exercises In the nineteenth century, the scientific community seriously thought about the fundamental problem of biology: the problem origin of species. Leaving aside the Bible version – for thousands of years, uniquely the most authoritative source knowledge – naturalists have wondered: how is evolution traits, and with them – whole species? Two points of view on this the question is usually associated with the theories of Jean-Baptiste Lamarck and Charles Darwin. The Lamarck hypothesis is based on the idea of heritability acquired traits, i.e. traits that have developed in the body during life. Lamarck model can be formulated so: “first – a sign, then – inheritance.” Classic (and boring order) example – this is the formation of the neck of a giraffe. By Lamarck, the ancestors of giraffes had to crank their neck all the time, to reach the top leaves on tall trees. Such neck “exercise” was passed on to their descendants, who continued stretch higher and higher – as a result, through many generations giraffes began to resemble a tower crane. Darwin approaches the question evolution on the other hand. It can be formulated as follows: “first – inheritance, then – a sign. “According to Darwin, signs are not formed focused exercise, and natural selection. Exercise neck as such, according to Darwin, cannot be directly transmitted offspring. But among any group of giraffes there will be animals with a neck shorter, and will be – with a neck more authentic. The last will get more food, which means they will survive and multiply better – this is natural selection. The cycle, repeated many generations, and leads to the formation of the most bizarre (and ridiculous, if we are talking about giraffes) forms of living. At the beginning of the XX century, it became clear that hereditary information is embedded in the chromosomes (and inside the chromosomes – in deoxyribonucleic acid), and basic principles of genetics. This led to Darwin’s theory single-handedly prevailed in the scientific community, and interest in Lamarckism preserved only in a historical context. Indeed, with introducing the concept of a gene, Lamarckism has become absurd: because you you will carry a computer around the city, it will not develop a system navigation. All changes must begin with a change in itself “code”, that is, with genetic mutations. Last sad attempt to depart from these principles was undertaken by Trofim Lysenko in USSR 30s Very attractive for the ideology of the time had the idea that signs can be developed purposefully, direct effect on the parent organism, and not choosing from options offered by nature. Not so simple So, acquired traits are not inherited. if you will break your nose, your children will not be crooked. And yet the name Lamarcke increasingly pops up in serious scientific literature last ten years. Of course, no one is going to cancel genetics and return to the experiments of Lysenkoists. But as in many similar cases, a detailed study of the genome and mechanisms inheritance revealed that a categorical denial of heritability acquired signs are not too far-sighted. In the XVII – XIX centuries. excavations destroyed by the eruption of the volcano of Pompeii revived interest in ancient culture and partly gave impetus to development neoclassicism. Although examples are epigenetic (literally – “supra-genetic”) mechanisms of inheritance were known before, the real Pompeii of Lamarckism can be considered the place of Overkalix on north of Sweden. Its feature was, firstly, in relative isolation, and secondly, in its exceptional meticulousness residents. Starting from the 16th century, they led generation after generation detailed records about the population of the town, their origin, reasons death, as well as about everything more or less significant, with them what happened: for example, about crops and weather conditions (and with that, and with that in the north of Sweden at that time was not very). As a result, in disposal of Lars Bigren, happening, as you might guess, from Overkaliks himself and his colleagues turned out to be a unique base data describing literally everything that happened to the whole by the human population for hundreds of years. Having done colossal data analysis work, scientists compared mortality from diabetes and cardiovascular disease statistics of harvests and food prices. It would seem that everything is predictable: if we eat too much, then we get sick more. But the results turned out to be much more interesting. It turned out that the availability of food in childhood affects not only the current, but also on subsequent generations. And it affects negatively. In other words, if your father or even grandfather grew up in a famine – your chances of developing diabetes or atherosclerosis fall significantly. Here we read, here – not read Leaving the experimental results themselves as food to meditation for grandmothers, vigilantly watching the satiety of their grandchildren, Consider the fact of transmission of “information about hunger” by inheritance. There is typical Lamarckism: the “exercise” of the body, “hardened” famine, inherited and stored at least in for two generations. Isn’t that against genetics? On the in fact, “supragenetic” inheritance does not contradict, but complements the concept of DNA as a carrier genetic information. In the case of the inhabitants of Overkaliks, as in most other “vital” epigenetic examples inheritance, we do not yet know the specific mechanisms behind observable phenomena. But we know about the fundamental existence such mechanisms – many of them are described in detail on simpler ones, experimental systems. Best known way to convey a sign of inheritance bypassing the DNA sequence is its chemical modification. DNA sections are not equivalent: some of them are read actively, some are silent. Methylation (i.e. adding a small chemical group of one carbon atom and three hydrogen atoms) to one of the DNA nucleotides can lead to “shutting down” the gene, which includes this nucleotide. After DNA cell division doubles: each cell inherits its copy. It turns out that in such cases the “drawing” can also be copied. methylation! Finally, methylation can be transmitted by inherited: methylation of the DNA of the embryo will be “copied” with DNA methylation of sperm and egg. Roughly speaking, in addition to genes proper we can inherit information about which genes work, and which do not. In addition to methylation, there is a mass other mechanisms, but in principle they are similar. Now imagine that DNA methylation can be affected by the environment. It is much easier to imagine than a direct change in the sequence environment DNA For example, hunger in Overkaliks causes in his minors residents increased secretion of a certain hormone A. This hormone affects the cells of the body (including those forming eggs or sperm) and causes production in them enzyme B. This enzyme, in turn, either methylates, or, on the contrary, removes methylation from a certain set of genes, such changing the distribution of “on” and “off” genes – and since the process occurs in the progenitors of germ cells, he recorded in the future offspring of overkalix children. Physiology or Psychology Of course, not every sign transmitted from generation to generation, provided by DNA or its methylation. Religiosity, for example, is also transmitted “by inheritance, “but that doesn’t mean that it must explained by changes associated with genes (although there are some data). However, the boundary between purely physiological and pure social forms of “inheritance” is quite difficult to carry out. IN ultimately any social or intellectual activity can be reduced to hormones and nerve impulses. In the work on the flaw maternal care in rats underwent physiological changes, further reflected in their ability to exert the same maternal care. We are inclined to consider this vicious circle. physiological in rats, but in the case of humans it would be about “social depression”, that is, about the psychological effect. With another hand, there are many examples of inheritance of acquired characteristics, in which the social component is difficult to detect. For example, how shows a study on rats, nicotine during pregnancy affects not only the fetus itself, but also at least two subsequent generations, causing them an increased tendency to asthma and other pulmonary disorders. Similar results were obtained for alcohol and a number of other psychoactive substances. Important to emphasize that in these works, after the initial exposure of the toxin to the body mothers or fathers later generations never encountered the test substance. The consequences, therefore, persisted in offspring regardless of the direct effect. In other words, heredity is not just DNA. These are absolutely all qualities and signs that we pass on to our children, and they to ours, and it doesn’t matter in what form: genetic, epigenetic or simply psychological. Therefore, future parents, perhaps, will be useful sometimes remember Lamarck.
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