Genetics of human behavior. Research on the genetic basis of behavior

Behavior genetics

(behavioral genetics) - a field of knowledge that explores genetic and trace determinants in variability animal behavior and psychological characteristics of a person (in the latter case, the term human behavioral genetics is sometimes used). In Russian, in relation to the study of a person, it is more appropriate to use the term, since it is understood as a set of external actions and actions of a person, and the scope of this concept does not include, for example, sensory thresholds, psychophysiological features (see), formal characteristics of cognitive processes, etc.

Brief psychological dictionary. - Rostov-on-Don: PHOENIX. L.A. Karpenko, A.V. Petrovsky, M. G. Yaroshevsky. 1998 .

Behavior genetics

A branch of genetics devoted to the study of the patterns of hereditary conditioning of the functional manifestations of the activity of the nervous system. The main task is to describe the mechanisms of realization of genes in behavioral traits and to highlight the influence of the environment on this process. Along with other research methods, the genetic selection method is used here, due to which the properties of the nervous system and behavioral features can be purposefully changed. Each inherited trait of behavior usually has a complex polygenic character. Animals from the lower rungs of the evolutionary ladder (insects, fish, birds) are characterized by low variability of innate, instinctive actions due to the genotype. As evolutionary development progresses, the process of formation of conditioned reflexes becomes more and more important, and the genotype less and less determines phenotypic variability. Information important for adaptation is not only acquired in one's own experience, but can be transmitted from parents to offspring through direct contacts, due to conditioned imitative reflexes. Data obtained in the genetics of behavior are of particular importance for the study of human nervous activity in pathologies: often mental retardation and mental illness are caused by heredity and are associated with genetic disorders.

Dictionary of practical psychologist. - M.: AST, Harvest. S. Yu. Golovin. 1998 .

Behavior genetics Etymology.

Comes from the Greek. genos - origin.

Category.

Section of genetics.

Specificity.

It is devoted to the study of the patterns of hereditary conditioning of the functional manifestations of the activity of the nervous system. Its main task is to describe the mechanisms of gene realization in behavioral traits and highlight the influence of the environment on this process. Each inherited trait of behavior has, as a rule, a complex polygenic character. Animals that are on the lower rungs of the evolutionary ladder (insects, fish, birds) are characterized by low variability of innate, instinctive acts due to the genotype. As the process of formation of conditioned reflexes becomes increasingly important in evolutionary development, the genotype less and less determines phenotypic variability. Information important for adaptation can not only be acquired in one's own experience, but can be transmitted from parents to offspring on the basis of direct contacts, due to imitative conditioned reflexes. The data obtained in the genetics of behavior are of particular importance for the study of human nervous activity in pathology: often mental retardation and mental illness are hereditary and are associated with genetic metabolic disorders, changes in the number and structure of chromosomes.

Methods.

Psychological Dictionary. THEM. Kondakov. 2000 .

BEHAVIOR GENETICS

(English) behavioral genetics) - a section of genetics that studies the patterns of hereditary determination of structural and functional features of n. With. G. p. allows you to understand the nature of the hereditary transmission of behavioral characteristics; reveal the unfolding ontogeny a chain of processes leading from genes to traits; isolate the influence of the environment on the formation behavior within the potentialities given genotype.

Using the genetic selection method properties n.With. and features of behavior m. directionally changed. The inheritance of differences in behavioral traits is, as a rule, a complex polygenic character.

It has been experimentally shown that the species stereotype of animal behavior has a very rigid hereditary conditionality. The low variability of innate, instinctive acts is especially characteristic of animals that are on the lower rungs of the evolutionary ladder - insects, fish, birds, but even in insects, behavior can be. modified by making temporary connections. At the same time, behavior is not a simple result of evolutionary changes; it plays an active role in evolution, because through behavioral adaptations, the action of selection in the animal population is manifested and the regulation of its structure and abundance is ensured. Hereditary information from parents to offspring can be transmitted on the basis of direct contacts, due to the development of imitative conditioned reflexes and other ways of perceiving and transforming information (the so-called signal heredity).

Of particular importance for G. p. is the study of human nervous activity - in normal and pathological conditions. Often and mental illnesses have a hereditary etiology associated with genetic metabolic disorders, changes in the number and structure of chromosomes, and so on. genetic disorders. Cm. . (I. V. Ravich-Shcherbo.)

Big psychological dictionary. - M.: Prime-EVROZNAK. Ed. B.G. Meshcheryakova, acad. V.P. Zinchenko. 2003 .

Behavior genetics

Field of study related to the genetic basis of behavior. The main thesis of this approach is that genetic differences largely explain the difference between people and their response to the environment.

Psychology. AND I. Dictionary-reference book / Per. from English. K. S. Tkachenko. - M.: FAIR-PRESS. Mike Cordwell. 2000 .

See what "genetics of behavior" is in other dictionaries:

Behavior Genetics- the doctrine developed by J. Piaget, at the center of which is the study of psychological mechanisms that determine the structure and development of knowledge. It attempts to combine the data obtained in the exp… Psychological Dictionary

Behavior genetics- a field of behavioral science based on the laws of genetics (See Genetics) and studying to what extent and how differences in behavior are determined by hereditary factors. The main methods of studying G. p. on experimental ...

Behavior genetics- a science that studies the role of hereditary factors in shaping the behavior of animals. It is believed that most behavioral traits are controlled by many genes (polygenic inheritance) and environmental factors. Probably the harder... Dictionary of trainer

Behavior genetics- (behavior genetics), the science of the genetic basis of behavior and a psychologist, a human being. Arguments in favor of the determinism of behavior by hereditary factors are concentrated around the dilemma: nature or upbringing, i.e. is it… … Peoples and cultures

Behavior genetics- [Greek. gengtikos referring to birth, origin] a field of knowledge that studies genetic and environmental determinants in the variability of animal behavior and human psychological characteristics (in the latter case, the term is sometimes used ... ... Encyclopedic Dictionary of Psychology and Pedagogy

Behavior genetics- a section of genetics that studies the relationship and dependence of the hereditary gene program of a person (and in general any living organism) and its behavior. Here, the patterns of hereditary transmission of the properties of genes to the qualities and properties of the human ... ... Fundamentals of spiritual culture (encyclopedic dictionary of a teacher)

- (behavior genetics). The study of the relationship between behavior and the genetic structure of the individual ... Psychology of development. Dictionary by book

Behavioral genetics- G. p. is nothing but the application of genetic principles and laws to the study of behavioral variables. Intelligence, personality and psychology. anomalies make three osn. areas of research. in psychology, where the methods of G. p. Po ... ... Psychological Encyclopedia

Genetics Great Soviet Encyclopedia

Genetics- I Genetics (from the Greek. génesis origin) is the science of the laws of heredity and variability of organisms. The most important task of G. is the development of methods for managing heredity and hereditary variability in order to obtain the forms necessary for a person ... ... Great Soviet Encyclopedia

23072 04.06.2005

A study in New Zealand deserves mention. This study made scientists think about whether it is even legitimate to talk about a hereditary predisposition (tendency) to antisocial behavior. Perhaps a more accurate concept would be the genetically determined vulnerability (insecurity) of some children in relation to adverse, traumatic events.

On our website, there have already been publications about adoption more than once. Many questions arise from potential adoptive parents about the heredity of children from dysfunctional families. We publish an article by M.V. ALFIMIVA, Candidate of Psychological Sciences, Leading Researcher of the Laboratory of Clinical Genetics of the Scientific Center for Mental Health of the Russian Academy of Medical Sciences, on whether behavior is inherited.

What is the heritability of a psychological trait
People differ from each other in a number of psychological characteristics. These differences are caused both by different living conditions and dissimilar genotypes, since people's genotypes contain different forms of genes. The relative contribution of heredity and environment to the diversity of people in terms of psychological properties and behavior is studied by psychogenetics. To assess the influence of heredity and environment on human behavior, scientists compare people with different levels of genetic commonality (identical and fraternal twins, siblings and half-siblings, children and their biological and adoptive parents).
Many genes exist in multiple forms, just as there are different forms of the gene that determines eye color. Some genes have dozens of forms. The genotype of a particular person contains two copies of each gene, the forms of which may be different, or they may be the same. One is inherited from the father, the other from the mother. The combination of forms of all genes is unique for each human organism. This uniqueness underlies the genetically determined differences between people.
The contribution of genetic differences to the diversity of people in psychological properties reflects an indicator called the "heritability coefficient". For example, for intelligence, the heritability rate is at least 50%. This does not mean that 50% of the intellect is given to a person by nature, and the remaining 50% must be added through training, then the intellect will be 100 points. The coefficient of heritability has nothing to do with a particular person. It is calculated to understand why people differ from each other: whether differences arise because people have different genotypes, or because they were taught differently. If the coefficient of heritability of intelligence turned out to be close to 0%, then one could conclude that only training forms differences between people and the application of the same upbringing and educational methods to different children will always lead to the same results. High values ​​of the heritability coefficient mean that even with the same upbringing, children will differ from each other due to their hereditary characteristics. The end result, however, is not determined by genes. It is known that children adopted into prosperous families, in terms of the level of intellectual development, are close to their adoptive parents and can significantly exceed biological ones. What then is the influence of genes? Let us explain this with the example of a specific study.
Scientists examined two groups of adopted children. The conditions in foster families were equally good for all, and the biological mothers of the children differed in their level of intelligence. Biological mothers of children from the first group had above average intelligence. Approximately half of the children from this group demonstrated intellectual abilities above average, the other half - average. The biological mothers of the children of the second group had a somewhat reduced (but within the normal range) intelligence. Of this group, 15% of children had the same low intelligence scores, the rest of the children had an average level of intellectual development. Thus, under the same conditions of upbringing in foster families, the intelligence of children, to a certain extent, depended on the intelligence of their blood mothers.
This example can serve as an illustration of the significant differences between the concept of heritability of psychological qualities and the heritability of certain physical characteristics of a person, such as the color of eyes, skin, etc. Even with a high level of heritability of a psychological trait, the genotype does not predetermine its final value. The genotype determines how the child will develop in certain environmental conditions. In some cases, the genotype sets the "limits" of the trait's severity.

The influence of heredity on intelligence and character at different ages
Studies show that genes are responsible for 50-70% of the diversity of people in terms of intelligence and for 28-49% of differences in the severity of five "universal", the most important personality traits:
- self-confidence,
- anxiety,
- friendliness
- consciousness,
- and intellectual flexibility.
This data is for adults. However, the degree of influence of heredity depends on age. The results of psychogenetic studies do not support the widespread belief that with age, genes have less and less influence on human behavior. Genetic differences, as a rule, are more pronounced in adulthood, when the character has already formed. The values ​​of the coefficient of heritability of most of the studied psychological properties are higher for adults than for children. The most accurate data were obtained on the hereditary conditionality of intelligence. In infancy, the intrapair similarity of fraternal twins is as high as for identical twins, but after three years it begins to decline, which can be explained by the large influence of genetic differences. At the same time, the increase in differences does not occur linearly. In the course of a child's development, there are stages in which differences between children are caused primarily by the influence of the environment. For intelligence, this is the age of 3-4 years, and for the formation of personality - the pre-adolescent age of 8-11 years.
In addition, different genetic factors act at different ages. So, among the hereditary factors that cause differences in intelligence, there are both stable, i.e., acting at all ages (these are, perhaps, genes associated with the so-called "general intelligence"), and specific for each period of development (probably, some genes that determine the development of particular abilities).

Influence of heredity on antisocial behavior
Since in all developed countries the crime and alcoholism of biological parents are common causes of the loss of a child's birth family and placement in a foster home, we will take a closer look at psychogenetic data on the influence of heritability on these forms of behavior. Family and twin studies of criminal behavior have been conducted for more than 70 years. They give very different estimates of heritability, most often falling in the 30-50% range. The "upper" values ​​of heritability are obtained by studying twins. Some researchers believe that the twin method can overestimate heritability, as it does not always allow one to separate genetic influences from the special environmental conditions in which identical twins grow up. By the method of studying adopted children, the values ​​of the heritability coefficient are approximately 2 times lower than in the study of twins.

Danish Adoption Study
(cm. )

The most systematic studies of the heritability of criminal behavior by studying adopted children were carried out in the Scandinavian countries - Denmark and Sweden. Thanks to the cooperation of adoptive parents and a number of authorities, Danish scientists were able to trace the fate of more than 14,000 adopted persons between 1924 and 1947. Figures 1 and 2 show the results of a study of criminal records in men raised in foster families. They refer only to crimes against property, as the number of violent crimes was low.

Picture 1 . The number of families analyzed, differing in the presence of a criminal record in the biological and adoptive father (Danish study).

Figure 2. Percentage of sons with a criminal record in families that differ in terms of the criminal record of the biological father and the adoptive father (Danish study).

Figure 2 shows that the proportion of convicts among children whose biological fathers were criminals is slightly higher compared to those children whose biological parents did not break the law. In addition, it turned out that the more convictions the biological father has, the higher the risk for the offspring to become a criminal. It was also shown that brothers adopted by different families tended to concordance (coincidence) in criminal behavior, especially in cases where their biological father was a criminal. These data indicate a certain role of heredity in increasing the risk of criminal behavior. However, as in the above example with intelligence, it follows from the data in Figure 2 that unfavorable heredity does not predetermine the future of the child - of the boys whose biological fathers were criminals, 14% subsequently broke the law, the remaining 86% did not commit illegal acts.
In addition, it turned out that the foster family has a particularly strong influence on children with unfavorable heredity, which can be both positive and negative. Of the boys raised in foster care, 16% later committed crimes (versus 9% in the control group). Among the biological fathers of these children, 31% had problems with the law (against 11% in the control group). That is, although the crime rate among adopted children was higher than in society on average, it was almost two times lower than among their biological fathers. According to some scientists, this indicates that a favorable environment in the foster family reduces the risk of criminal behavior in children with burdened heredity.
But in some cases, the family environment can increase the risk of criminal behavior. As can be seen from Figure 2, children whose biological and adoptive fathers had a criminal record committed crimes more often than others. (Fortunately, there were very few such families (Fig. 1)). This means that there are genotypes that have an increased vulnerability to adverse aspects of the family environment (such phenomena in psychogenetics are called genotype-environment interaction).

Swedish study
In a study of foster children in Sweden, scientists at first found no even weak link between the criminal record of children raised by foster parents and the behavior of their biological fathers.
Among the Swedes, crimes were mainly the result of alcohol abuse. When scientists excluded this type of crime from the analysis, they found a weak positive relationship between the presence of a criminal record in the offspring and their blood fathers (Fig. 3). At the same time, the crimes in both generations were not serious. Mostly it was theft and fraud.
The sensitivity of children with hereditary burden to the peculiarities of the foster family was also confirmed. Among adopted Swedes, there was no increase in crime rates compared to the national average, despite the fact that among their biological parents the percentage of convicts was increased. Among the foster parents-Swedes there were no persons who had a criminal record. Those. the most favorable family environment "neutralized" the effect of the genetic load.
On the other hand, the highest risk of breaking the law was observed in those children with unfavorable heredity, whose foster family had a low socioeconomic status (Fig. 3).

Figure 3 . Percentage of convicted persons among adopted persons depending on family type (Swedish study).

American study
Scandinavian research included an analysis of the behavior of adopted children born in the first half of the 20th century. Similar results were obtained in the modern work of American scientists from the state of Iowa. True, it did not analyze a criminal record, but the presence in adopted children of a tendency to antisocial behavior of a wider spectrum. Behaviors that warrant a diagnosis of antisocial personality disorder were assessed and included frequent arrest-worthy behaviors, as well as traits such as lying, impulsiveness, irritability, disregard for safety, irresponsibility, and lack of conscience. We also took into account a number of characteristics of the foster family that could influence the formation of such inclinations. Figure 4 lists these characteristics and shows the main findings of the study when the adoptees were already adults (aged 18 to 40). Only data on men were analyzed, as the number of women with "antisocial behavior" was too small. Of the 286 men studied, 44 were diagnosed with antisocial personality disorder. The results indicated that three factors make an independent contribution to the development of this disorder: 1) the conviction of the biological parent (genetic), 2) drunkenness or antisocial behavior of one of the members of the foster family (environmental), 3) the placement of a child with unfavorable heredity in a family with low social -economic status (genotype-environmental interaction).

Figure 4 The results of studying the causes leading to the formation of an antisocial personality in the American study of adopted children (arrows indicate a statistically significant relationship between the characteristics of parents and the formation of antisocial inclinations in children).

What is a genetic predisposition to antisocial behavior?
Obviously, in humans, genes do not trigger specific behaviors in the same way that some of the instinctive actions of animals do. The relationship between the risk of criminal behavior and genes is mediated by psychological characteristics. Moreover, it is known that various unfavorable combinations of psychological properties can influence the risk of criminal behavior, and each of these properties is controlled by several or a large number of genes and various environmental factors.

The first candidate for the role of the biological "substrate" of antisocial tendencies was the Y chromosome (a chromosome that is contained only in the male genotype and determines the male sex). In about one in 1,100 men, as a result of biological errors in the complex process of creating a germ cell, the genotype ends up with two or more Y chromosomes instead of one. These men are characterized by low intelligence (near the lower limit of the norm) and high growth. In the 1960s, it was first shown that there are a disproportionate number (4%) of men with an extra Y chromosome among serving criminals with reduced intelligence. At first, the connection between this genetic defect and criminal tendencies seemed obvious: since men are more aggressive than women, commit crimes more often, and, unlike women, have a Y chromosome, the presence of two or more Y chromosomes should lead to the formation of an aggressive “superman”. But later it turned out that criminals with an extra Y chromosome are no more aggressive than other prisoners, and they get into prison mainly by stealing. At the same time, in men with this genetic pathology, a relationship was found between a decrease in intelligence and the likelihood of being convicted. It is possible, however, that reduced intelligence did not affect the risk of committing a crime, but the risk of being caught and imprisoned. For example, one of the men with an extra Y-chromosome broke into houses several times with the help of break-in while the owners were on the premises.

Studies of men with extra Y chromosomes lead to at least two important conclusions. First, the link between genes and crime cannot be explained by a genetically determined increase in aggressiveness or cruelty, as "common sense" might suggest. This conclusion is consistent with data from studies of adopted children, in which the influence of heredity was found only for crimes against property. Secondly, even among men with such an obvious hereditary anomaly as an extra Y chromosome, the majority do not become criminals, we are only talking about a slight increase in the risk of such behavior among them.

Since the mid-90s, scientists have been searching for specific genes that could influence the risk of criminal behavior. All the data obtained so far still need to be confirmed and clarified. However, a study in New Zealand deserves mention. It showed that among boys who were abused in the family, carriers of a form of the gene that provides a higher activity of the MAOA enzyme in the body were less prone to antisocial acts than carriers of another form of the gene - low activity. Among children who grew up in prosperous families, there was no connection between antisocial tendencies and the MAOA gene. That is, persons with certain genetic characteristics turned out to be less vulnerable to parental abuse. This study made scientists think about whether it is even legitimate to talk about a hereditary predisposition (tendency) to antisocial behavior. Perhaps a more accurate concept would be the genetically determined vulnerability (insecurity) of some children in relation to adverse, traumatic events.

Influence of heredity on alcohol abuse
It has long been observed that crime and alcohol abuse are closely related. Moreover, psychogenetic studies have suggested that there are "predisposition genes" common to these behaviors. Some similar patterns were also revealed in the influence of heredity and environment on crime and alcohol abuse. For example, for both forms of behavior, a significant influence of the general environment is found in adolescence. The influence of the common environment is manifested, in particular, in the fact that brothers and sisters growing up in the same family (even if they are not relatives) are more similar to each other in antisocial manifestations and habits associated with alcohol consumption than to their parents. However, alcohol abuse is a rather complex phenomenon from a behavioral and genetic point of view, since it includes both domestic drunkenness and alcoholism as a gradually developed mental illness (the main diagnostic feature of which is an irresistible psychological craving for alcohol). Obviously, the role of genes in these two cases is different, but it can be quite difficult to separate these two forms of alcohol abuse in a psychogenetic study. Perhaps that is why estimates of the heritability of alcoholism fluctuate quite widely. The most likely interval seems to be the range of 20-60%. Among the sons of alcoholics, according to various sources, an average of 20-40% falls ill, and among daughters - from 2% to 25% (an average of about 5%). At the same time, it can be considered established that the age at which alcohol began to be consumed, and the intensity of its consumption in the early stages, is completely determined by the action of the environment. Note that alcohol consumption at an early age (usually before 15 years of age) is a risk factor for the development of alcoholism. The absence of genetic influences on this trait points to the important role of parental behavior that deters adolescent alcohol use in preventing the development of alcohol dependence. At the same time, in the further escalation of alcohol consumption and the development of alcoholism, genetic effects and genotype-environmental interactions are clearly detected.
We emphasize, however, once again that a person is not born an alcoholic and there is no single “alcoholism gene”, just as there is no “crime gene”. Alcoholism is the result of a long chain of events that accompany regular drinking. A large number of genes influence these events to some extent. So, it depends on the character of a young man how often he will drink and whether he will know the measure, and the character, as already mentioned, depends both on upbringing and on the genotype. In addition, due to their genetic characteristics, people are to varying degrees sensitive to the toxic effects of alcohol. For example, in some Japanese, Koreans and Chinese, such a form of a gene was found that affects the processing of alcohol in the liver, the possession of which leads to very severe alcohol poisoning. A person with this form of the gene, after drinking alcohol, feels nausea, a rush of blood to the face, dizziness and irritation. These unpleasant sensations keep a person from further drinking, therefore, among the carriers of this form of the gene, there are almost no patients with alcoholism. Finally, not all people who regularly consume alcohol develop an irresistible craving for it. There are genes (they are being intensively searched now) that determine whether prolonged exposure to alcohol on the brain will lead to alcohol dependence. At the same time, genes do not trigger specific forms of behavior, they do not “force” a person to go and drink. If a person knows that they are predisposed to alcoholism, they can avoid situations in which drinking is encouraged and remain healthy.
Children of alcoholics are often referred to as a multiple risk group. Approximately 1/5 of them have various problems that require special attention from parents, teachers, and sometimes doctors. Mostly it is restlessness and neurotic disorders (tics, fear of the dark, etc.). Difficulties in assimilation of the school curriculum are observed less often, other more serious disorders, for example, convulsive conditions, are even less common. These disorders are not manifestations of any defects in the genetic apparatus and are caused by unfavorable conditions in which mothers bear pregnancy and raise babies. Studies of adopted children have shown that the alcoholism of blood parents does not increase the likelihood that a child will develop any serious mental disorder in the future.
Summing up the existing data on the influence of heritability on antisocial behavior and alcoholism, we can draw the following conclusions.
- There is a positive, although very weak relationship between the crime of blood fathers and their sons who grew up in foster families.
- This pattern is found only for minor crimes, so there is no reason to believe that the risk of becoming a criminal in adopted children is explained by a genetically determined increase in aggressiveness or cruelty.
- Evidence indicates that a favorable family environment can neutralize innate characteristics associated with an increased risk of criminal behavior, and an unfavorable one can increase them.
- The development of antisocial tendencies is not inevitable even in carriers of serious genetic anomalies.
- The age at which they began to drink alcohol and the intensity of its consumption in the early stages is completely determined by the action of various environmental factors. Genetic effects and genotype-environmental interactions are found only for the subsequent escalation of alcohol consumption and the development of alcoholism.

Willerman L. Effects of familyon inteelectual development. Cit. according to "Psychogenetics" by I. V. Ravich-Shcherbo and others.
Environmental influences in psychogenetics are divided into general and individual environment. The general environment is understood as all non-hereditary factors that make compared relatives from one family similar to each other and not similar to members of other families (it can be assumed that for psychological properties these are upbringing styles, the socio-economic status of the family, its income, etc.). The individual environment includes all non-hereditary factors that form differences between family members (for example, a circle of friends, classmates or teachers unique for each child, gifts or actions of adults that he remembers, forced isolation from peers as a result of some kind of trauma or other individual events).

From time immemorial, the study of human behavior has been considered a territory in which molecular scientists, geneticists and other adherents of the “mechanistic” view of living things have absolutely nothing to do: everything is so complicated, spiritualized and generally far from the banal interaction of molecules. However, this taboo is gradually becoming a thing of the past, and many studies are already beginning to snatch out of the darkness of the unknown the individual details that link genetics and behavior. This note, based on a short review published in the journal Science, will successfully complement the material " Genes control behavior and behavior controls genes”, which appeared on the Elements website and is based on articles and reviews published in the same issue Science.

It is hard to believe that human behavior and other aspects of higher nervous activity can be somehow connected with genes. You can often hear in response to a statement about, for example, a sexual (and therefore genetically predetermined) difference in mathematical abilities, an annoyed statement like “well then show me a mathematical gene!”. Of course, no “math gene” exists, but this does not mean that mathematical abilities (as well as more general abilities to concentrate attention, perceive abstract logical constructions, etc.) are not “encoded” at the DNA level. The fact is that all complex phenomena, one way or another connected with higher nervous activity and not directly caused by some severe hereditary disease, are based on the most complex effects of the interaction of many genes, only enabling the formation of certain neural structures and personal characteristics, but by no means determining them by 100%. If a person has at least a thousand copies of the "mathematical gene" (if it existed), without the systematic development of abilities, of course, nothing will work, and dreamers should remember this well. It's just that, probably, many newspaper headlines like "The gene for cruelty has been discovered" or "Divorce is genetically predetermined" can give the impression that both the successes and failures of people in all areas of life can already be explained at the level of genes (but do readers of such newspapers know, what are genes?), and, therefore, it’s not worth it to strain too much.

And what, it would be convenient to explain poor social adaptation by heredity, and the behavior of all the “private owner” genome of militancy that cuts and rushes from strip to strip. By the way, are Hemingway's famous depressions caused by problems with the dopamine receptor? Or maybe adultery is a direct consequence of the structural features of the vasopressin receptor gene? Research indicates a certain connection between these phenomena, although, of course, one should not explain one's own failures and other people's successes solely by this.

Decades of research involving families and relatives, twins and adopted children have shown that there is a definite (and sometimes quite significant!) relationship between the genotype and a predisposition to a certain type of behavior in model situations, but compared to the search for the most complex patterns that determine this relationship, identifying mutations that cause development, such as Huntington's disease, looks like child's play. It is now quite obvious that the ability to speak fluently and learn languages, responsiveness and willingness to help others and other spiritual qualities cannot be determined by any one gene, but are formed under the influence of many factors (of which the main one so far, probably, is still is education). In addition, the same gene is likely to be involved in many processes at once - for example, predisposition to depression, overeating and impulsive behavior, making the task of establishing unambiguous relationships almost impossible. The study of these factors is undoubtedly the most difficult task ever faced by geneticists, behaviorists and psychologists.

Love does not love...

Genetic scanning for the strength of marriage bonds? What? Isn't it too similar to the slogan of one of the magical salons? Despite the solid shade of yellowness of such a statement, one Canadian company does offer for $ 99 to analyze the vasopressin 1a receptor gene in the couple who applied ( AVPR1a), which became infamous as hard heart gene or divorce gene. However, how can such a test be more informative than the long-established chamomile divination?

You can’t explain everything with genes, but in Sweden they conducted a study involving 500 same-sex twins, each (or each) of which was in a public or civil marriage for at least five years. The subject of the study was the relationship between the structure of the AVPR1a receptor gene promoter and the results of a survey that included questions like how often do you kiss your partner or “how often do your interests and those of your partner intersect outside the family circle”. (This questionnaire was supposed to assess the "temperature" of family relationships.) It turned out that for men, the gene promoter sequence AVPR1a which was shorter (and several variants were found), less strong attachment to wives is characteristic than for the rest. These men are less likely to marry, and in marriage they are more likely to experience a crisis in family relationships. So, has the “divorce gene” been found yet? Perhaps there is no need to rush: reality may be more complicated than this scheme, convenient for revelers.

However, neither in family life nor in friendship are there such unambiguous connections as in pathophysiological states (although ...), and, therefore, one should not hope for "genetic fortune tellers".

I will survive

Some people are called weak-willed because they are not able to resist the circumstances around them, and even a minor incident can upset them, while others steadfastly overcome all adversity and inevitably move towards their intended destination. However, even in this kind of resilience, it seems that it was not without genetics: emotional ups and downs are associated with a neurotransmitter serotonin, whose transporter (SERT) will be discussed later.

In the now classic 1996 work by Klaus-Peter Lesch ( Klaus-Peter Lesch) it was found that the length of the regulatory sequences preceding the gene SERT, is also related to human behavior. Those of the 505 volunteers who were classified by the questionnaire as susceptible to neurosis (depression, anxiety, etc.) had a short regulatory sequence present in one or two copies, while the more “calm” experimental subjects were found to have a long variant of the promoter . The "short" form of the promoter causes more active secretion of serotonin into the synapses, which has been shown in both animals and humans to cause anxiety and anxiety. However, one should not be deceived by the idea of ​​absolutely accurately predicting a person's character based on the results of genotyping: according to statistical processing, the short form of the promoter SERT responsible for only 4% of depression and negative emotions. However, psychologists note that even 4% in the case of personal qualities is already a lot, because before that scientists could not find a single gene, variations in which gave at least such a level of causation.

Another paper, published in 2003, analyzed the relationship between stressful life events and related experiences in a group of 847 people who were asked about the presence of depression between the ages of 20 and 26 years. Among the subjects who did not have to experience “blows of fate” during this period (such as the death of loved ones, dismissal from work, personal failures, etc.), a significant connection between the gene SERT and the probability of occurrence of depression was not revealed (and this probability itself was low). The most interesting thing was in the group of people who experienced four or more stressful episodes: 43% of the carriers of the "short" isoform of the promoter SERT reported a depressive period associated with troubles, while among the holders of the "long" option, the number of depressions was almost two times lower. In addition, it was found that in people with a "short" promoter SERT in adulthood, depression is more likely to occur if they experienced abuse in childhood; in the other part of the studied group, such a pattern was not observed.

But even here, of course, it is premature to state anything concrete. Many scientists with numbers in their hands prove that for such weak effects, the size of the samples used is clearly insufficient, and the influence of serotonin and its transporter on physiology is so wide - these are sleep disorders, and cardiovascular activity, and schizophrenia, and autism, and the state of search thrills - that it is possible to judge their influence on behavior only in the most general terms.

belligerence gene

In 2006, it was discovered that a special form of the gene may be responsible for the "famous" warlike behavior of the New Zealand Maori tribe monoamine oxidase-A responsible for the breakdown of neurotransmitters in the brain. (I wonder if the abbreviation MAO-A coincidentally resembles the word Maori?). According to New Zealand researcher Rod Lee ( Rod Lea), 60% of Asians (including Maori) are carriers of a special, "belligerent" gene variant MAO-A, while in Caucasians this figure does not exceed 40%. However, Lee himself admits that it would be an oversimplification to blame all social problems - such as aggressiveness, gambling and various addictions - on a single gene.

In another study, using magnetic resonance imaging of the brain, it was demonstrated that in carriers of the "belligerent" allele MAO-A a special part of the brain, the amygdala, is much more excited ( amygdala) - in response to the presentation of emotional stimuli, such as images of scary or disgusting faces. (The amygdala, or amygdala, is the region of the brain that processes socially relevant information associated with emotions such as fear and distrust.) The activity found clearly proves that such people have a harder time controlling their emotions and that they are more likely to respond with aggression. to any emotional stimulus.

In the case of the gene MAO-A, as well as for the serotonin transporter, it has been shown that carriers of the "belligerent" allele are more likely to have "behavioral problems" if they experienced abuse in childhood (and if not, then the probability of "antisociality" is almost three times lower). How events in the field of human relationships - even as unpleasant as child abuse - are able to affect gene expression - yet seems to remain a mystery.

Testosterone acts similarly to the “fly in the ointment” in the case of “antisocial” behavior: when comparing 45 male alcoholics, and even with a criminal past, with the control group “without aggravating drugs”, it turned out that the “buoys” not only have reduced expression of MAO-A (i.e., there is a "belligerent" allele), but also increased content testosterone. And although the "militant gene" is unlikely to be responsible for the entire spectrum of social problems, it definitely has some influence on behavior (especially in the "cocktail" with testosterone).

Live fast, die young

What do Janis Joplin, Jimi Hendrix and Kurt Cobain have in common other than the fact that they are all members of the mystical 27 Club? The world of rock musicians is perhaps a good place to find people with a broken (and sometimes completely gone) system of positive reinforcement that forms the traditional scale of human values. In the case of such a violation, a person ceases to receive positive emotions from everyday things that are pleasant to most people, and hits all hard in search of unhealthy forms of new sensations such as addiction to alcohol, tobacco, drugs or gambling. However, is the dopamine receptor that responds to the neurotransmitter responsible for this? dopamine, the lack of which leads to a violation of the system of positive reinforcement?

The A1 allelic form of the D2 dopamine receptor does not “feel” dopamine very well, which may lead to a “dulling” of the sensations that accompany daily activities. Some scientists believe that it is the D2 receptor polymorphism that is the cause of addiction and a pronounced constant search for thrills, as well as antisocial behavior, including problems in relationships with other people.

A study involving 195 students from a New York State University showed that carriers of the A1 allele begin sexual activity earlier, but at the same time are less able to establish long-term relationships. In another study, it was shown that boys - carriers of one A1 allele - have a greater propensity for marginal and criminal behavior than the owners of two A2 alleles. True, heterozygous A1 / A2 "experimental" showed an even greater tendency of this kind, somewhat confusing the situation. One scientist even said about this gene that "there is more smoke than fire."

By the way, in the last issue Science there was even a work in which links are made between gene variants DRD2 and adherence to a particular political party, arguing that people with two "highly effective" A2 alleles are more gullible and easier to join any parties.

It is clear that in the genetics of behavior practically nothing is understood yet. However, another thing is also clear - that psychologists will soon, in addition to outdated Eysenck tests and other questionnaires, have to arm themselves with modern tools for analyzing the genetic characteristics of participants in their studies.

Adapted from Science News with abbreviations.

Literature

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Genetic studies of behavior are essential for a number of areas of biology and medicine. First, they must be the basis on which alone certain areas of the physiology of higher nervous activity can develop. The doctrine of individual differences in higher nervous activity (including the doctrine of its types) and the elucidation of the relative role of congenital and individually acquired components of behavior are impossible without genetic analysis.

Fully understanding this, IP Pavlov created a laboratory of genetics of higher nervous activity in Koltushi.

Secondly, genetics makes it possible, with the help of crosses, to separate and combine in the hybrid offspring those and other features of behavior with different morphophysiological properties of the organism and to elucidate the correlations between those and others. This opens up a new subtle method for studying the dependence of the formation of behavior on the morphophysiological properties of the organism, which is impossible with the help of modern surgical or physiological methods.

Thirdly, the study of the genetics of behavior is of great importance for a number of problems in evolutionary theory. Genetically determined features of animal behavior play a role in the structure of populations. Hereditary differences in behavior determine the formation of isolated populations of various sizes, which is of great importance for the rate of the evolutionary process.

Fourth, the study of the genetics of animal behavior is important for finding new methods for the most rational domestication of economically useful animals. This is of particular practical importance for fur farms.

Fifth, the genetics of behavior is necessary to create experimental models of nervous diseases. Several dozen neurological hereditary diseases have been described in mice and are being studied as experimental models of human disease. The genotypic model of epilepsy has been extensively studied in rodents in all countries. In 1965, an international colloquium in France was devoted to this issue.

Genetic research into behavior began shortly after the rediscovery of Mendel's laws. The material accumulated to date shows that many features of behavior are inherited according to Mendel's laws, but in most cases a number of factors change the picture of their inheritance.

For genetic studies of behavior, defensive responses in animals have proved to be a convenient model. A number of studies have been devoted to this issue.

Rice. 1. Inheritance of shyness in mice

In 1932, Davson carried out studies on the mode of inheritance of a pronounced fearfulness in wild mice compared with the weak severity of this trait in laboratory mice. A total of 3376 individuals were studied. An objective recording method was used: the time of running down a corridor (24 feet long) while scaring the mouse with a moving cursor. A preliminary study revealed a high correlation (r=+0.92+0.003) between separate trials of the same mice, indicating a significant stability of the studied behavioral traits. The average running time for wild mice was 5 s, for domestic mice it was 20 s.

In the first generation, an almost complete dominance of the fearfulness of wild mice was observed. Among individuals of the second generation, the variability in the degree of shyness increased significantly (Fig. 1) compared to F 1 . Based on his research, Dowson concluded that the difference in shyness between wild and domestic mice is determined by two or three genes. Virtually all wild mice are homozygous for these dominant genes. In addition to the main genes that determine the degree of fearfulness of the parental generation, several modifiers influence the formation of the studied traits.

This study showed the inheritance of behavioral features according to Mendel's laws, but at the same time it illustrated that this inheritance is carried out, as in the case of most quantitative differences between traits, with the participation of polymeric genes. The heritability of behavioral characteristics according to the same laws by which morphological traits are inherited clearly indicates that the evolution of behavior is carried out as a result of natural (or artificial) selection of hereditary changes. This was also pointed out by Charles Darwin in the chapter on instincts in The Origin of Species. Significant material has now accumulated to support Darwin's views on this issue.

As an example showing the role of selection in changing the nature of behavior, we can cite the work on geotaxis in Drosophila melanogaster. On fig. 2 shows the results of selection for changes in geotaxis. Selection for 65 generations led to divergence: lines with clearly expressed positive and negative geotaxis were created. Reverse selection (carried out between the 52nd and 64th generations) led to a change in the nature of geotaxis. On the basis of hybridological analysis, the authors come to the conclusion about the polygenic nature of the changes in the behavior of flies that depend on genes located in autosomes and the X chromosome.

Along with the hybridological analysis of differences in the characteristics of behavior, the phenogenetic method is very important, which makes it possible to establish the mechanism of the hereditary realization of genotypically determined traits. An example of a simple dependence of the inheritance of various behavioral features on morphological traits is the choice of the temperature optimum in mice. So, for example, in the works of Herter it was shown that wild mice and albinos choose different temperatures during their rest. It turned out that the temperature optimum of wild mice is 37.36 °, white - 34.63 °. A simple pattern of inheritance of this optimum is found. The study showed that the temperature optimum is determined by the thickness of the fur and the thickness of the epidermis on the skin of the mouse abdomen. In white mice, the density of fur is less than in wild ones (the number of hairs per unit area is 45:70, and the thickness of the epidermis is greater - the ratio is 23:14). A particularly clear relationship has been established between the temperature optimum and the density of wool. In hybrids F i ; the temperature optimum is close to the optimum of white mice: it is 34.76 ± 0.12°, the coat density is 43.71 hairs per unit area.

Rice. Fig. 2. The result of selection for positive and negative geotaxis in Drosophila melanogaster (summary curves)

The results of reverse selection are shown on a reduced scale (selection of flies with the most negative geotaxis in the positive line and the most positive in the negative line). Bold curves - selection for negative geotaxis; thin - to positive. The dots indicate sections of the curve representing generations for which there are no data (according to Erlenmeier-Kimmling et al., 1962).

Backcrossing (F1 ≈ wild mice) resulted in splitting into two groups. In one group, the optimum corresponded to that in white mice (+34.56°±0.12) with a fur density of 52.7 hairs; in the other group, the temperature optimum was close to the optimum in wild mice (37°); In this group, the number of hairs per unit area was 70.94. Raising mice at different temperatures, Herter came to the conclusion that, in addition to the hereditarily determined thickness of the epidermis and the thickness of the coat, which determine the optimum temperature, there is also a modification adaptation of each mouse to the temperature in which it is brought up. This modification device can change the optimal choice of a resting place characteristic for a given individual. This example clearly showed the dependence of the formation of an adaptive reaction of behavior on the genotypically determined morphological features of the organism.

An example in which, using the genetic method, it was possible to differentiate the inheritance of a type of behavior from the inheritance of morphological characters was Mazing's work on the study of photoreaction in Drosophila melanogaster. The study showed that through selection over 26 generations, it was not possible to isolate a line in which all individuals would respond or not respond to light. This indicates an incomplete expression of the genes responsible for the different activity of flies with respect to light. Flies with reduced eyes (Bar, Bar eyeless) react to light, but their reaction is slow. Among the eyeless individuals from the eyeless line, there are flies that are actively responsive to light. This showed that the eyes are not the only receptor for light. The sharp weakening of the photoreaction noted in flies with reduced wings suggested that the photoreceptors were located on the wing. Experiments with cutting off the wings of flies from a line that actively reacts to light led to a significant weakening of positive phototaxis. This confirmed the assumption about the significant role of the wing surface in the photoreaction of flies. However, genetic analysis has shown that this is obviously not the case. The system of genetic analysis was carried out in such a way that vestigial flies were crossed with a normal line of flies that actively reacted to light. Positive phototropism turned out to be a completely dominant trait. The vestigial flies appearing in F 2 bred again with normal flies. After 17 generations of “crossings” of the vestigial gene into the normal line, when the genotypic environment of the vestigial gene was practically replaced by the genotype of normal flies, it turned out that flies with reduced wings began to actively respond to light. This showed that the weak photoreaction of the vestigial flies is determined by the non-reduction of the wings. This study confirmed the view of some entomologists that the perception of light is carried out by the entire surface of the body, and is not associated specifically with the eyes or with the surface of the wing.

An example of the obvious dependence of hereditary behavior on differences in the activity of the sex glands can be found in the studies of McGill and Blythe, in which it was shown that the onset of sexual activity in males, leading to mating after the previous mating (with ejaculation), is extremely different in different strains of mice. In mice of the C57BL/6 line, this time was on average 96 h, and in the DBA/2 line, it was 1 h. Rapid recovery of sexual activity is dominant. When backcrossing F 1 ? C57 BL/6 the recovery time of sexual activity averaged 12 hours; at the same time, a large variation was observed, indicating splitting for this trait.

In the study of defensive reactions, it was possible to discover the dependence of the hereditary implementation of behavioral traits on various functional states of the organism. Studies conducted on dogs have shown that the passive-defensive reaction (timidity, cowardice), which manifests itself in relation to various external factors, is due to the genotype.

In our work, we studied the defensive behavior of dogs in relation to humans. In adult dogs, under the same conditions, this property is fairly constant. The correlation coefficient between two assessments made with an interval of 1–2 years is +0.87±0.04. Two groups of dogs served as material for the genetic study: the first group (224 individuals) consisted mainly of German Shepherds and Airedale Terriers raised in various conditions (kennels and individuals); the second group included 89 dogs, mostly mongrel. All dogs of this group were brought up in the nursery of the Institute of Physiology. I. P. Pavlova in Koltushi. The study showed that the fear of humans in dogs is a genotypically determined trait that has a dominant or incompletely dominant nature of inheritance. The manifestation and expression of this property of behavior is highly dependent on a number of conditions.

Another defensive reaction, active-defensive (reaction of aggression or malice towards a stranger), was studied by us on 121 offspring obtained from different types of crosses. The criterion for aggressive behavior was the teeth grasping of an object extended to the dog by a stranger. All dogs on this basis are divided into two alternative groups. The correlation coefficient calculated between the individual assessments of this feature at intervals of 1–2 years (r=+0.79±0.04) illustrates the rather high constancy of the manifestation of this feature of behavior. The analysis carried out indicates the genetic conditionality of this feature of behavior, which has a dominant nature of inheritance.

Scott in 1964 published a paper on the inheritance of the barking response in various breeds of dogs. They established great differences between individual breeds. The biggest differences are found between Cocker Spaniels, which bark very frequently, and Basenjis (African hunting dogs), which hardly bark. The author explains the differences found by different thresholds of dogs' reactions to external stimuli. In spaniels, it is very low, in basenji it is high. F 1 hybrids are close to spaniels in their barking reaction. This indicates the dominant nature of the inheritance of this property. The nature of the splitting of hybrids showed that the found differences can be most easily explained by the presence of one dominant gene, which determines the low threshold of the barking reaction to external stimuli. However, in addition to the inheritance of the main gene, the formation of this trait of behavior is influenced by a large number of modifiers and external conditions.

Passive and active defensive reactions are inherited independently. If they appear in the same individual, then a kind of maliciously cowardly behavior is formed. With a sharp expression, one of these components of behavior can completely suppress the manifestation of the other. This was shown by the use of hybridological analysis with the parallel use of pharmacological preparations that change the degree of expression of individual components of the defensive complex of viciously cowardly dogs.

An analysis of the hereditary implementation of defensive behavioral reactions has shown that their manifestation and expression are highly dependent on the degree of general excitability of the animal. It turned out that genetically determined reactions of behavior may not manifest themselves in the phenotype of an animal with its low excitability. However, the offspring obtained by crossing such animals with excitable individuals exhibit a pronounced defensive behavior.

Rice. 3. Formation with age of varying degrees of "predominant" behavior of one sex over the other in dogs of different breeds

The abscissa shows the age of the dogs; along the y-axis - the percentage of the predominant behavior of dogs of one sex over the other, calculated on the basis of the time of taking possession of the bone, given to two dogs of the same sex, located in the test room for 10 minutes (according to Pavlovsky, Scott, 1956).

Hyperexcitability is inherited, as has been shown in various animals, as a dominant or incompletely dominant trait. In dogs, hyperexcitability is inherited as a dominant or incompletely dominant trait. Increased motor activity in rats is a genotypically determined trait and is inherited as an incompletely dominant trait. In Leghorn chickens, according to Golovachev, the threshold of long-term excitability (rheobase) of motor nerve fibers of the sciatic nerve exceeds that of Austrolorp chickens and is a dominant trait that depends on a limited number of genes.

The dependence of the manifestation of cowardly behavior in dogs on different degrees of excitability can be illustrated by the example of crossing German shepherds with Gilyak huskies. The slightly excitable, non-cowardly Gilyak Laikas were crossed with excitable, non-cowardly German Shepherds. All the offspring of this crossing (n = 25) had increased excitability and pronounced cowardice (Fig. 3). In this crossing, the genotypically determined passive-defensive reaction was inherited from the Gilyak Laikas, in which it did not manifest itself due to the insufficiently high excitability of their nervous system. The presence of a subthreshold passive-defensive reaction in them was proved by an artificial increase in the excitability of their nervous system. After the introduction of cocaine, the Gilyak Laikas showed a passive-defensive reaction. But not only the manifestation, but also the degree of expression of the hereditarily determined reaction of the behavior of animals depends on the degree of general excitability of their nervous system. By changing the state of excitability of the nervous system, it is possible to change the expression of defensive reactions of behavior. With an increase in the degree of excitability as a result of the introduction of pharmacological or hormonal drugs (thyroid hormone), in parallel with an increase in excitability, an increase in defensive behavior also occurs. Conversely, removal of the thyroid gland, which reduces the degree of excitability of the animal, leads to a weakening of defensive reactions.

The dependence of the manifestation and expression of the genes that determine these forms of behavior on the genotypically determined activity of the endocrine glands was studied by us using the example of the inheritance of fearfulness in wild (Norwegian) rats when they were crossed with laboratory rats. When using as a test the speed of running a 6-meter corridor when a rat was frightened by a sound stimulus, it was found that the shyness of wild rats almost completely dominated in F 1 hybrids. In backcrossing (F 1 - laboratory albinos) a clear segregation occurred. Wild (Norwegian) rats have a relatively larger weight of adrenal glands compared to laboratory ones due to a more strongly developed cortical layer. In F 1 hybrids, the relative weight of the adrenal glands up to 3 months of age was intermediate between the size of the adrenal glands of the parents. At older ages, the relative size of the adrenal glands approaches that of laboratory rats. By this age, the increased excitability and fearfulness of F 1 hybrids decreases. Removal of the adrenal glands, as well as the pituitary gland, leading to the reduction of the adrenal glands, led to a weakening or even complete elimination of shyness in one and a half month old F 1 hybrids. This weakening of fearfulness occurred against the background of a sharp decrease in general excitability. Thus, in addition to the inheritance of genes for shyness in wild rats, there apparently occurs an inheritance of an increased functional activity of the adrenal cortex, which causes an increased excitability of F 1 hybrids. This example illustrates the presence of some genotypically determined morphophysiological relationships that determine the hereditary implementation of behavioral traits.

Rice. Fig. 4. Protracted motor excitation of the rat after sound exposure (lower figure) and its absence (upper figure)

The lower curve is the mark of the action of stimuli (20 - weak, 130 - strong); the upper curve is a record of the animal's motor activity (according to Savinov et al., 1964)

Biochemical analysis of the hereditary implementation of defensive behavior and the degree of general activity in mice is carried out by Maas. Two strains of mice were studied in this study: C57 BL/10 and BALB/C. First strain mice are more active, less shy, and more aggressive towards their species than mice of the second strain. The content of serotonin (5-hydroxytryptamine) and norepinephrine, mediators of excitation of the nervous system, was studied. The study showed that the C57 BL/10 line contains less serotonin in the brainstem (pons, middle and intermediate) than BALB/C. In the former - 1.07±0.037 mg/g, in the latter - 1.34±0.046 mg/g; the difference is statistically significant: P< 0,01). Достоверных различий в содержании норадреналина не обнаружено. Уровень содержания серотонина в определенных отделах мозга (особенно в гипоталамусе) играет роль в «эмоциональном» поведении животного. Опыты с введением фармакологических препаратов, которые меняют различные звенья обмена серотонина, показали, что найденные генетические различия в содержании серотонина у обеих линий мышей связаны с различными механизмами связывания этого нейрогормона нервной тканью. У мышей линии BALB/C происходит более быстрое освобождение серотонина нервной тканью, чем у мышей линии С57 BL/10. Эти исследования интересны в том отношении, что указывают новые пути возможной биохимической реализации генотипа в формировании особенностей поведения.

The question of the relationship between individually acquired and innate factors is extremely important for the phenogenetics of behavior. Fundamentally, this question does not differ from one of the main problems of phenogenetics: the influence of the genotype and external factors on the formation of morphological characters.

A convenient example for considering the relative role of innate and individually acquired factors in the formation of behavior is the defensive reactions of dogs. The first work done by I. P. Pavlov's collaborators in Koltushi in 1933 was to study the influence of various conditions of their upbringing on the behavior of dogs. Vyrzhikovsky and Maiorov, dividing two litters of outbred dog puppies into two groups, brought them up in different conditions. One group was brought up in isolation, the other in complete freedom. As a result, the grown dogs of the first group had a pronounced cowardice, the dogs of the second group did not possess it. IP Pavlov gave this fact the following explanation: puppies have a "reflex of natural caution" in relation to all new stimuli; this reflex is gradually inhibited as one gets acquainted with the whole diversity of the external world. If the puppy does not meet with a sufficient number of diverse stimuli, he remains cowardly (feral) for life.

Subsequent studies on the influence of the genotype on the manifestation and expression of cowardice depending on the conditions of detention, carried out by us on dogs, showed the interaction of genotypic and external factors in the formation of defensive behavior. The material for this study was German Shepherds and Airedales (n = 272). Dogs of both breeds were brought up in different conditions: one group - with individuals, where it was possible to come into contact with all the diversity of the outside world, the other - in kennels, where the dogs were in considerable isolation from external conditions.

In table. 1 shows data on the manifestation and expression of cowardice in these dogs. With isolated upbringing, the percentage of individuals with a passive-defensive reaction increases in both groups. However, among German Shepherds, compared with Airedale Terriers, the number of cowardly individuals with a sharp expression of this property of behavior significantly increases (this difference is statistically significant).

Table 1. Manifestation and expression of passive-defensive reaction in dogs of different breeds raised in different conditions

These data indicate that the manifestation and degree of expression of the cowardly behavior of dogs brought up in isolation are carried out depending on the genotype of the animal. Thus, the "wildness" of dogs, which is expressed in the fearfulness of individuals raised in isolated conditions, is a certain norm of the reaction of the nervous system, determined by the genotype, to the conditions of their upbringing. Despite the fact that the domestication of the dog began no later than 8,000–10,000 years ago (Scott and Fuller, 1965), the modern dog has retained a genotypically determined tendency towards wildness, which is easily detected even under slightly isolated conditions of education.

Dogs taken out to uninhabited territory run wild, as happened, for example, in the Galapagos Islands, where they were brought by the Spaniards to destroy goats, which were a source of food for English pirates. This population of feral dogs exists today. Human-caught puppies are easily tamed.

The difference in the form of expression of the passive-defensive reaction of free-living populations depending on the different genotype was described by Leopold in 1944. Wild turkeys, domestic and hybrid populations were studied. This population was obtained from crossing wild and domestic turkeys and lived freely in Missouri. Wild turkeys, having discovered danger at a great distance, immediately fly away. Individuals of the hybrid population, having detected danger, let the alien close to them and, flying off two hundred yards, begin to graze calmly. Wild turkey chicks have a pronounced tendency to hide at the approach of an enemy. In the hybrid population, this form of behavior is weakened: the chicks tend to run away or fly away when approaching them at close range. Studnitz also described differences in the degree of human fear in the same species of birds living in different geographical stations. The most striking example of such a difference in human fear is the thrushes (Turdus viscivorus). In England, they are not at all shy, in Northern Europe they are very shy, although they are not pursued by man.

The presence of genotypic differences in a population, which determine the formation of a passive-defensive reaction of behavior, is undoubtedly one of the most important factors in the rapid restructuring of defensive behavior when an enemy appears. Such an example was described by F. Nansen. In 1876, when the first ships of the Norwegian fishing fleet penetrated deep into the North, to the shores of Greenland, seals (Cystophora cristata) were so not afraid of people that they were killed by a blow to the head. However, after a few years, they became shy: they did not always let even a gun shot.

A similar process of increasing fear of a person occurs almost always where a person enters a previously uninhabited territory and begins to hunt for animals of the local population. Of course, in addition to selecting individuals with the most pronounced passive-defensive reaction and individuals who have learned to fear humans more easily than others, tradition can play an important role in the above restructuring of defensive behavior in a population. All the various alarm signals, the direct imitation of the behavior of the parents, can be, along with selection, a system of non-hereditary rearrangement of the population's behavior. However, if there are no hereditary prerequisites for the manifestation of a passive-defensive reaction, one traditional experience, apparently, is not able to determine the fear of an enemy that exterminates a given population. Such a case was described by Yu. Huxley on the example of the geese of the Falkland Islands. Despite intensive extermination by humans, they showed only slight signs of fear of humans, which did not protect the population from extermination. The presence of genotypic differences in the formation of the passive-defensive reaction is a prerequisite for the restructuring of the defensive behavior of the population. It has been established that the intensification of the passive-defensive reaction occurs not due to the direct hereditary fixation of the fright reactions of the surviving individuals, but due to the natural selection of the most cowardly individuals or those that had a genotype that contributes to the most rapid formation of fearfulness during their pursuit.

Without a special genotypic analysis, it is difficult to differentiate between hereditary and non-hereditary variability in behavior, traditions from generation to generation. This has long created conditions for unreasonable assumptions of direct inheritance of acquired skills. Even such a strict and objective researcher as I. P. Pavlov, in a very cautious form, allowed for the possibility of inheriting the results of individual experience. In 1913, he wrote: “... it can be assumed that some of the newly formed conditioned reflexes later turn into unconditioned ones through heredity” (p. 273). His more definite statement on this issue in Lectures on Physiology belongs to the same period: “Are conditioned reflexes inherited? There is no exact evidence for this, science has not yet reached this point. But one must think that with a long period of development, firmly developed reflexes can become innate” (p. 85). In the early 1920s, I. P. Pavlov instructed his collaborator, Studentsov, to study the inheritance of conditioned reflexes in mice. These experiments, which did not give positive results, were often referred to, ranking I. P. Pavlov among the supporters of the inheritance of acquired traits. This forced IP Pavlov to state his attitude to this issue in a letter to Hutten (Pravda. 1927. May 13). Throughout the rest of his life, I. P. Pavlov stood on strictly genetic positions. He created a laboratory in Koltushi for the study of the genetics of higher nervous activity, in front of which, next to the monument to Descartes and Sechenov, a monument to Gregor Mendel was erected. As a permanent consultant in his genetic research, I. P. Pavlov invited the largest genetic neuropathologist S. N. Davidenkov, he also consulted with N. K. Koltsov.

Genetic work was carried out by selection in individual families of dogs according to the typological features of their higher nervous activity. The results of these studies, which showed the role of the genotype in the formation of the typological properties of higher nervous activity, were published after Pavlov's death. These studies have shown that genotypic factors play a significant role in the formation of typological features of higher nervous activity. In various families of dogs, in which selection was made in the direction of the degree of strength (or weakness) of the excitation process, a correlation was observed in these features of nervous activity between brothers and sisters in separate litters of dogs: r=+34±0.1.

The results of crossings between dogs with a strong and weak nervous system, which were started during the life of IP Pavlov, are summarized in Table. 2.

The degree of strength of the nervous system is related to sex: males (n = 31) have a stronger nervous system than females (n = 22). The probability of matching P(x 2) turned out to be less than 0.05, which can be considered statistically significant. The question of the role of genotypic factors in learning has been studied since the well-known works of Yerkes and Bagg. Yerkes studied the learning ability of two strains of rats, one uninbred and one inbred from the Wistar Institute. The results of this work showed that the average learning time of non-inbred lines is somewhat less than that of inbred ones (52.25 lessons for the former and 65.00 for the latter). Bagg investigated individual and family differences in the behavior of mice when finding their way through a fairly simple maze. A line of white mice, which Bagg founded in 1913 (line C, now BALB/C), was compared with a line of yellow mice. It turned out that the average learning time of white mice for 15 experiments was 27.5 ± 2.0 s with 9 errors per lesson; the learning time of yellow mice was 83.0 ± 7.0 s with two errors per lesson. There was a similarity in the learning ability of individuals of the same litters.

Table 2. Data on the inheritance of strong and weak types of nervous activity in dogs

A detailed study of the role of genotypic factors in the development of conditioned reflexes was carried out by Vicari. This study examined the learning ability of Japanese dancing mice (Mus Wagneria asiatica) (inbreeding 20 years), three strains of normal mice (Mus musculus), albinos Bagg (inbreeding 14 years), weak brown (inbreeding 17 years) and abnormal eyes (abnormal x -ray eyed) (inbreeding 6 years). It turned out that each strain of mice has a characteristic learning curve. Crossing between individuals of separate lines has shown that fast learning dominates over slower learning. The author points out that the nature of splitting in the second generation suggests that the difference in learning between brown and albino Bagg is due to monofactorial, although the possibility of a more complex pattern of inheritance cannot be denied. Differences in learning between the Bagg line and Japanese dancing mice are determined, in the author's opinion, by the presence of several hereditary factors. The study (performed on 900 mice) indicates a large role of genotypic factors in the speed of learning in mice.

However, the differences found in the analysis of such a complex trait as the speed of learning do not yet prove genotypically determined differences in the intimate mechanisms of the brain associated with the learning process itself. The presence of genotypically determined differences in the unconditioned reflex reactions of the studied lines can largely determine the found differences in learning ability. As such an example, one can cite the exceptionally thorough work of M. P. Sadovnikova-Koltsova. After studying learning in a maze (Hamptoncourt) in 840 rats, the author by selection brought out two lines: one is fast learning, the other is slow. The index of fast learning rats (logarithm of the time spent on 10 counting experiments) is 1.657±0.025, slow learning - 2.642±0.043. The difference between both indices (D=0.985±0.05) turned out to be 20 times greater than the probable error.

Further analysis showed that the differences found between both lines of rats are due not to differences in their ability to develop conditioned reflexes, but to the greater shyness of the second line of rats (which descended to a large extent from wild Norwegian rats). During training in Ston's apparatus, in which the rat was urged on by slamming doors and therefore could not hide into the corner of the maze because of timidity, the training of both lines proceeded in the same way.

Thus, the selection did not select genotypes that contribute to more or less rapid learning, but genotypes that cause a different degree of fearfulness, which changed the learning curve. A similar example of the dependence of the inheritance of the rate of formation of positive conditioned reflexes in chickens and sturgeons on unconditioned reflexes can be found in the work of Ponomarenko, Marshin, and Lobashov. The authors explain the inheritance of the features of the excitatory process, which is one of the main parameters in the development of conditioned reflexes, by their correlation with the nature of unconditioned reflexes. In fish, there is a clear dependence of the rate of formation of conditioned reflexes on the level of excitation of the alimentary unconditioned center, which, in turn, depends on the hereditarily determined growth rate. These examples show that in the genetic analysis of such a general complex property as learning, the most careful and, if possible, parallel physiological analysis is necessary.

Geneticists have known for many years that certain genes have a pleiotropic effect on morphological and behavioral traits. In 1915, Sturtevant discovered that a recessive gene located at one end of the X chromosome in Drosophila melanogaster and causing a yellow body color instead of normal gray also reduces the copulatory ability of males.

Further studies showed that the reduced sexual activity of males of this line is associated with a violation of the time and method of "courtship" of females before copulation. Yellow males, planted with females, begin to care for them after an average of 9.6 minutes, normally colored - after 4.9 minutes. In order to start copulation, males of the yellow line court on average for 10.5 minutes, normal - for 6.0 minutes. In addition, in males of the yellow line, one of the main signs of courtship with females is disturbed - the vibration of the wing directed towards the female. This act of behavior by the male is a necessary ritual that the female perceives through her antenna in order to be prepared for copulation. In males of the yellow line, vibratory shocks are weaker than in normal males, and are carried out at longer intervals.

In the lines of yellow flies, females have an increased (statistically significant) readiness for copulation compared to normal females, which is a compensatory adaptation for the possibility of normal mating. This increased mating readiness in yellow females is not a pleiotropic effect of the yellow gene. It is determined by the selection of other genes that lower the threshold of copulative readiness. This example is interesting in that it shows how a single mutation with a pleiotropic behavior-altering effect and subsequent selection creates a lineage that Bastok believes could lead to a physiologically isolated ecotype.

A striking example of the pleiotropic effect of genes on the morphological features and behavioral characteristics of rats is described by Keeler and King. By studying various coat color mutations that appear in wild (Norwegian) rats kept for many generations in captivity, the authors found that mutant individuals differ from wild ones in their behavior. The mutant individuals with black coat color were especially sharp in their defensive behavior. These rats don't bite. The authors believe that their data indicate one of the possible ways in which wild rats were domesticated. They suggest that laboratory albinos did not arise as a result of long-term selection of small mutations that changed their "wild" behavior, but as a result of several mutations, some of which had a pleiotropic effect on coat color. A significant role in the domestication of rats was played by the selection of the black coat color gene in combination with the piebald gene. In most laboratory albinos, these genes are in a cryptomeric state and do not appear due to the absence of the main pigmentation factor in albinos.

Studies that have revealed the presence of a broad pleiotropic effect of genes that influence behavior are being conducted by Belyaev and Trut on foxes. Studies on silver-black foxes bred in fur farms showed a large heterogeneity of the population in terms of defensive behavioral reactions. Three main types of defensive behavior have been distinguished: active-defensive (aggressive), passive-defensive (shy), and calm (absence of both types of defensive behavior). The results of the crosses performed showed that the largest percentage of foxes with one or another characteristic behavior is observed in the offspring of parents characterized by the same type of behavior: the largest percentage of aggressive foxes are born in the offspring of crossing aggressive individuals; cowardly offspring are found in the greatest percentage when cowardly parents are crossed with each other. Selection for "calm" behavior has been effective. It is important to note that the analysis carried out does not allow us to speak about the influence of one or another type of defensive behavior of the mother on the nature of the behavior of the offspring, which could have been formed as a result of imitation. A significant percentage of individuals in fur farms are individuals with cowardly behavior, which is a likely result of the isolated rearing (cage keeping) of foxes.

The study of the sexual activity of females (time of estrus) and their fecundity showed that in calm females, estrus occurred in all age groups earlier than in aggressive individuals. In most groups, this difference was statistically significant. A relationship was also found between the nature of defensive behavior and the fertility of females. The greatest fecundity was found in calm females, the least - in maliciously cowardly ones. The difference between these groups is statistically significant. Statistically significant differences (in the first year of mating) were also found between the number of offspring of calm females compared with the number of puppies born from vicious and cowardly females. An interesting relationship was found between the features of behavior and color. The largest amount of silvery (zone-colored) hair is found in foxes with one form or another of defensive behavior. Among vicious foxes, the smallest percentage of individuals with a low content of silver hair turned out to be. Among the foxes selected for a calm form of behavior (such selection turned out to be effective), there were individuals with anomalies in the structure of the fur coat. Since the amount of silver in the fur of foxes increases the value of the skin, it becomes clear why the farms retain vicious and cowardly individuals (less convenient in caring for them) and why the selection of foxes according to the time of their estrus, which is carried out in fur farming practice, does not give a sufficient effect. . The research conducted by Belyaev shows the importance of studying the genetics of behavior in breeding for economically useful traits in fur farms, opens up new ways of approaching the problem of domestication of animals and shows the role of behavior in the formation of the morphophysiological characteristics of the population.

Above, data were presented that show the role of the action of genes on the formation of the behavior of an individual at different levels of its individual development. However, genotypic factors, as it has now been found out, exert their influence on the behavior of animals also through the establishment of various relationships between individuals in separate communities. One of the most well-studied ways in which genotype influences group behavior is the degree of aggression towards members of its own species. In each community of vertebrates, as a result of aggressiveness towards individuals of their own species, a behavioral hierarchy is established: some individuals turn out to be “dominant”, others “subordinate”; "subordinate" individuals are afraid of "prevailing". The hierarchical system of community behavior depends on many factors. As a rule, young individuals are subordinate to older ones. Males outside the breeding season are predominant over females. However, during the breeding season, as shown in birds, females begin to predominate over males. Males, standing at the lowest level of the community hierarchy, are not chosen by female birds for mating. Females that are low in the hierarchy of the community, if they mate with aggressive, dominant males, they themselves begin to occupy a predominant position in the community.

A large role in the place that this individual will take in the hierarchy system in the community, as shown by a number of studies, is played by genotypic factors. This has been clearly shown in mice. Mice of different inbred lines have different degrees of aggressiveness, which determines the hierarchy in the community of these animals. For example, of these mouse strains, C57BL/10 mice (black) tend to be the most dominant, followed by C3N mice (zone gray), and BALB mice (white) are the most subordinate.

However, despite the clear role of the genotype, which determines the structure of the community in mice, a large role of the conditions of education for the degree of aggressiveness of each mouse became clear. It turned out that mice of easily submissive lines become more aggressive when brought up in isolation and begin to subdue mice of those lines that were brought up in the community. However, if a mouse from a low-aggressive strain is brought up with mice from an aggressive strain, its aggressiveness increases. Placed then in a community of low-aggressive mice, it will rank high in the dominance hierarchy.

The genotype plays an important role in the formation of the hierarchical structure of the community in the carnivora family. Studies conducted by Pavlovsky and Scott have shown that the degree of prevalence in dogs is determined by the genotype and is extremely variable among different breeds. This difference comes out in a vivid degree from 11 weeks of age. The clearest predominance (especially males over females) was found in African hunting dogs (Beisenji) and fox terriers. In Beagles and Cocker Spaniels, this predominance is rather blurred (Fig. 4). The sharply expressed hierarchy of behavior in the dog community makes it extremely difficult for new individuals to enter this community. The weakly expressed hierarchy of behavior in beagles and spaniels is, according to the authors, the result of long-term artificial selection, in which the most aggressive individuals were culled, which did not give the opportunity to include new dogs in the pack. A strong hierarchy in the community of the canine family is observed in wild species, such as wolves and the least domesticated dog breeds, and is of great biological importance in the struggle for habitat.

So, in the Eskimo villages, several communities of huskies are formed. Puppies, as a rule, can walk around the village with impunity. However, after the onset of puberty, when they begin to mate, each dog adjoins a community and after that bites if it enters the territory occupied by another community (Tinbergen).

In wild animals, a community is usually formed, consisting of a different number of members. This may be a family or a herd that is not directly related. One of the main reasons for the formation of such communities is the protection of the occupied territory from the penetration of members of other communities into it. The number of individuals in a community is largely determined by genotype, as was shown in Leopold's work on turkeys. It turned out that wild turkeys form smaller flocks than individuals of the hybrid population.

Thus, genotypically determined aggressiveness towards individuals of their own species has a biological significance. First, it promotes the formation of physiologically isolated groups of biotypes, which is the most important condition for speciation. Secondly, by creating a hierarchical system of behavior, aggressiveness puts the weakest individuals in the least favorable conditions for reproduction, which favors the negative selection of the least adapted individuals. And finally, thirdly, aggressiveness towards individuals of its own species leads, as was vividly shown by K. Lorenz using the example of the struggle for existence carried out among coral reef fish, to a uniform distribution of individuals of the same species throughout the territory. habitat, which determines its most rational use.

Thus, the specificity of the action of genes comes down to the fact that they not only play a crucial role in shaping the behavior of an individual, but also largely determine the relationship of animals within individual communities, thereby influencing the formation of the structure of the population and the course of the evolutionary process.

The use of genetic methods to study the physiological mechanisms underlying pathological disorders of higher nervous activity is clearly seen from the intensive study in many countries of the world of hereditary diseases of the nervous system in animals.

The most widely studied genetic model of nervous system disease is experimental rodent epilepsy. In 1907, a mutation was discovered in rabbits of the Viennese white breed, in which epileptic seizures developed under the action of various nonspecific external stimuli. Nachtsheim, by inbreeding, achieved seizures in 75% of the rabbits of his line. He came to the conclusion that the predisposition to seizures is determined by one recessive gene. However, several modifiers have an inhibitory effect on the hereditary implementation of this behavioral feature. The Nachtsheim rabbit line perished during World War II.

At present, a line has been developed in which almost 100% of individuals respond with convulsive seizures in response to the action of strong sound stimuli.

Convulsive seizures in mice and rats are widely used as an experimental model of epilepsy. Wit and Hall investigated the genetics of seizures (so-called audiogenic or reflex epilepsy) in mice, obtained by the action of a sound stimulus (usually using the sound of an electric bell with a strength of 100–120 dB). The authors crossed two inbred lines: C57 BL, in which seizures develop in 5% of cases in response to sound stimulation, with the DBA line, in which seizures develop in 95% of individuals. They concluded that an increased susceptibility to seizures is determined by a single dominant gene. However, subsequent studies conducted on the same lines of mice did not confirm the monofactorial picture of the study. Ginzburg and Starbuck-Miller, as a result of their long-term inheritances, conclude that the similar phenotypic expression of seizures observed in different sublines of mice (C57 BL/6 and C57 BL/10, DBA/1 and DBA/2) has a different genetic basis. . It is most likely that the DBA sublines “sensitive” to seizures have the genetic formula AABB, and the C57 BL sublines with low sensitivity have two recessive aavb alleles. Each of these genes is located on different autosomes. The most probable difference in the degree of dominance and the ratio of sensitive and insensitive individuals in F 2 and backcrosses is explained by the difference in each of the lines used in a number of modifier genes.

Physiological studies conducted in parallel with genetic analysis have shown that the predisposition to epileptic seizures in mice is associated with their general predisposition to the action of stress factors. In this case, oxidative-phosphorylating mechanisms, which are different in the studied lines of mice, seem to be of particular importance.

The phenotypic appearance and expression of convulsive readiness in mice is greatly influenced by various external factors. A striking example of such an effect is the increase in the convulsive readiness of DBA/1 mice and their hybrids obtained by crossing with C57 BL mice under the action of very small doses of radium. Mice that had been chronically exposed to gamma rays for a month since birth (total dose 0.14 rad) were found to be hypersensitive to the action of the sound stimulus.

A change in the general radiation background also affects the sensitivity of mice to the action of a sound stimulus. From May to October 1957, in DBA/1 mice in F i crossed with C57 BL, Starbuck-Miller found a significant increase in the number of seizures during sound exposure. According to the Atomic Energy Commission, this period coincided with an increase in overall radiation levels in America.

The development of convulsive seizures in rats under the influence of a sound stimulus is also genotypically determined. In the population of laboratory rats and the Wistar rat line, about 10–15% of individuals give convulsive seizures in response to a sound stimulus (bell 100–120 dB).

As a result of selection, we managed to obtain a line of rats that give convulsive seizures during sound exposure in 98–99% of individuals. Despite the clear genotypic determination of this pathological reaction in rats, the exact pattern of its inheritance is unclear. The data published by various authors are contradictory. The data obtained by LN Molodkina and I indicate only the obvious incomplete dominance of the increased sensitivity of rats to the action of sound stimuli. When rats of our line were crossed with insensitive unselected rats and Wistar rats in the first generation, 93 (69.9%) were sensitive individuals, 40 (30.1%) were insensitive.

Based on the nature of splitting in subsequent generations, it is still difficult to draw a conclusion about the number of hereditary factors that control the development of this pathology. However, in the complex complex reaction of rats to a sound stimulus, it was possible to isolate more simply inherited features of nervous activity. Protracted excitement turned out to be such a property. It is expressed in the fact that after several minutes (according to our standard 8) of sound exposure, despite the exclusion of the stimulus, the rat continues to be in a state of strong motor excitation, sometimes lasting tens of minutes (Fig. 4). This property was found in a striking form in one male of our sensitive line. As a result of selection and inbreeding, this feature of nervous activity was fixed. Protracted excitation turned out to be a recessive trait in relation to the absence of this functional property of nervous activity: all 68 F i hybrids sensitive to a sound stimulus, obtained by crossing rats of our line with unselected rats and Wistar rats, in which this property is absent, turned out to be without protracted excitation. When F 1 was crossed back with strained rats with prolonged excitation, out of 93 individuals sensitive to the sound stimulus, 70 turned out to be without prolonged excitation and 23 with prolonged excitation. This splitting is consistent with the hypothesis that prolonged arousal is due to two recessive genes. In this case, the expected splitting should be 69.75:23.25. However, when rats with prolonged excitation obtained from this crossing are crossed, along with rats with prolonged excitation, individuals without it are also born. This indicates that the analyzed trait is more difficult to control than two recessive genes, which are manifested in 100% of cases. Breeding a line of rats highly sensitive to sound stimulation with prolonged excitation was the most important step for the possibility of conducting pathophysiological studies. In rats of our line, in addition to epileptic seizures, a number of pathologies develop: the most important of them relate to the cardiovascular system - this is death from cerebral hemorrhages, changes in blood pressure, functional disorders (arrhythmias) of cardiac activity, etc. The main reason for the development of all these pathologies is the excitation of the brain under the influence of the action of a sound stimulus. The genotypic determination of the excitation threshold and the strength of the protective-inhibitory processes, on the one hand, and the functional state of the nerve centers, which depends on a number of external factors, on the other, determine the pattern of developing excitation. However, despite the multiplicity of factors involved in the development of this pathology, the relatively simple relationship between the process of excitation and inhibition determines the diversity of the observed stages of this process. These relationships, as was shown by Savinov, Krushinsky, Fless and Wallerstein, obviously boil down to the fact that excitation grows during the time of action of the sound stimulus, approaching a curve that has a linear character, and the inhibitory process that limits this excitation grows exponentially.

Research conducted on the genetics of behavior has established a number of facts.

First, it has been shown that many acts of behavior are controlled by a small number of genes, being inherited according to Mendel's laws. As a result of a combination of independently inherited acts of behavior, more complex, integral in their manifestation and expression forms of behavior are formed, which can be divided by both genetic and physiological methods. At the same time, a complex morphophysiological complex, such as domestication, can be determined by the selection of a small (even one) number of genes that have a pleiotropic effect on behavior and morphological characters.

Secondly, gene control of behavior is carried out at various levels of organization. Differences in behavior have been found that are controlled by genes acting at the cellular level, by genes that control the biochemical and physiological processes underlying different types of behavior, and, finally, by genes acting at the behavioral level, thereby determining the different structure of the population. With the elucidation of the role played by genotypic factors that control behavior in the formation of individual isolated microbiotypes in a population, and the establishment of the role of genotypic factors in different types of activity, a new direction opens up in studying the role of genetics in evolution and biogeocenology.

Thirdly, the hereditary implementation of behavioral reactions is extremely dependent on individual experience. Acts of behavior similar in their external manifestation can be due to various reasons. In some cases, they are formed under the leading influence of innate factors, in others - under the leading influence of individual experience. The difficulty in distinguishing between hereditary and non-hereditary variability of behavior without special genotypic analysis, and the possibility of transmission by imitation of certain traditions from generation to generation, has long created conditions for unreasonable assumptions of direct inheritance of individually acquired skills.

Fourthly, the genotypic conditionality of pathological reactions of nervous activity, similar to human diseases, has been established. Certain genotypically determined shifts in the general biochemical and physiological systems are found, which can underlie a wide range of pathological reactions of the body. This opens up the possibility of studying in model experiments on animals with a certain genotype the biochemical and physiological mechanisms underlying the development of a number of pathologies that the clinic encounters.

There is no doubt that the convergence of genetics and the physiology of higher nervous activity will not only enrich both of these sciences, but will also have a great influence on a number of other branches of biology.

Notes:

Experienced indicators of pedometers obtained after injection; pre-injection pedometer benchmarks.

Journal. total biology. 1944. V. 5, No. 5. S. 261–283.

Topical issues of modern genetics. M.: Publishing House of Moscow State University, 1966. S. 281–301.

Pavlov IP Lectures on physiology. L., 1952.

Despite the fact that there is continuous variability in the degree of strength between the studied individuals, in the table above all dogs are divided into two alternative groups: weak and strong.

Stress factors are understood as various non-specific stimuli that lead to profound violations of the body's regulatory mechanisms.