In anthropology, a number of hypotheses have been put forward that try to solve this problem, assuming that man became a man thanks to: life in water; mutations in the brain cells of hominids, caused by hard radiation from a supernova explosion, or reversals of the geomagnetic field; a mutant in the hominid community appeared as a result of heat stress. Let us consider these hypotheses in the order presented.

The hypothesis of the Swedish researcher J. Lindblad is very original. According to her, the South American Indians living in the rainforest are the most ancient people on Earth, and the predecessor of man was the “hairless monkey”, or “ixpitek”, leading an aquatic lifestyle. It is the reduced hairiness, upright posture, long hair on the head, emotionality and sexuality inherent only in humans that are due to the peculiarities of the lifestyle of the aquatic hominid (he spent most of the day on the shore). “As always, when a new way of life increases the percentage of survival,” writes J. Lindblad, “mutational changes in hereditary structures entail adaptation to the aquatic environment. Here it is expressed in a decrease in body hairiness and the development of a layer of subcutaneous fat. However, the hair on the head is long, an important factor for the survival of the young. In the first years of life, cubs have a particularly powerful layer of subcutaneous fat. The legs of the ixpitec are longer than the arms, the big toes are not opposed and point forward. The posture when walking is more straight - perhaps the same as ours. In other words, the Ixpitek has a completely human appearance, at least from a distance. Further development of the skull and brain led to the appearance of a modern type of man. Within the framework of such a direction of scientific research as “cosmic catastrophism”, which has recently been formed, a hypothesis has been put forward about the emergence of modern man in connection with the outbreak of a nearby supernova. It was recorded that a very surprising circumstance is that the outbreak of a nearby supernova in our Galaxy of a star in time (occurring once in 100 million years) approximately corresponds to the age of the oldest remains of Homo sapiens (35-60 thousand years ago). In addition, some of the anthropologists believe that the appearance of modern man is due to mutation. And pulses of gamma and X-ray radiation from a supernova explosion are known to be accompanied by a short-term increase in the number of mutations. In this case, the intensity of ultraviolet radiation, which is a mutagenic agent, sharply increases on the Earth's surface, which, in turn, initiates the appearance of other mutagens. Ultimately, we can say that the hard radiation generated by the supernova explosion could cause irreversible changes in brain cells, which led to the formation of intelligent mutants of the species? Homo sapiens. In any case, modern science connects with supernovae: the formation of the solar system, the origin of life and, possibly, the origin of the modern type of man with his civilization.

Another hypothesis comes from the fact that modern man is a mutant that arose as a result of the inversion of the earth's magnetic field. It has been established that the terrestrial magnetic field, which mainly delays cosmic radiation, sometimes weakens for reasons unknown so far; then there is a change in the magnetic poles, i.e. geomagnetic inversion. During such reversals, the degree of cosmic radiation on our planet will increase dramatically. Investigating the history of the Earth, paleomagnetologists have come to the conclusion that over the past 3 million years, the Earth's magnetic poles have changed places four times. Some of the discovered remains of primitive people belong to the era of the fourth geomagnetic inversion. Such an unusual combination of circumstances leads to the idea of ​​the possible influence of cosmic radiation on the appearance of man. This hypothesis is strengthened by the following fact: man appeared at a time and in those places in which the force of radioactive radiation turned out to be most favorable for changing the great apes. It was these conditions that arose about 3 million years ago in South and East Africa - during the period of separation of man from the animal world. According to geologists, deposits of radioactive ores were exposed in this region due to strong earthquakes. This, in turn, caused a mutation in some monkey species that was most predisposed to changing genetic traits. It is possible that about 3 million years ago, prolonged exposure to radioactive radiation so profoundly changed Australopithecus that he became able to perform the actions necessary for his safety and food supply. In accordance with this hypothesis, Pithecanthropus appeared about 700 thousand years ago, when the second change in the geomagnetic poles of the Earth occurred (250 thousand years ago), Neanderthal appeared, while the appearance of modern man falls on the fourth geomagnetic inversion. This approach is quite legitimate, because the role of the geomagnetic field in the life of organisms, including humans, is known.

The following hypothesis says that we all belong to the same subspecies of “reasonable man” and are descended from one foremother and one forefather, a very specific man and woman (more precisely, as it is now believed, a group of about 20 men and 20 women), whose descendants we are , now living people. More strictly, as we shall see, they should be called genetic Adam and Eve. Their real existence is recognized by the scientific majority, but some scientists still doubt this. Adam and Eve lived approximately 150-200 thousand years ago in Africa, and they still cannot be attributed to Homo sapiens, but rather to Homo erectus. They lived in different places and at different times. Naturally, they were not alone - around them and at the same time with them lived tens of thousands of other quite the same people. Certainly some of them are also our ancestors. The difference is that these others were the ancestors of some of us, maybe even many of us, but, fundamentally, not all of us. The concept of genetic Adam and Eve suggests that these two "humans" are the direct ancestors of ALL people now living on Earth.

This is the general hypothetical-theoretical situation in the development of the problem of anthropogenesis today. Not everything in it is fully clarified and explained, not everything scientists agree with each other. But there is nothing surprising in this, because we are dealing with the crown of the creation of nature - man. It is important to emphasize the following: in science it can be considered proven that man is a product of the natural development of nature. It has its roots in the biosphere of the Earth and is its legitimate child.

Concepts of ethnology

Ethnology - (from the Greek ethnos - nation, people, logic) ethnology, a science that studies the everyday and cultural characteristics of the peoples of the world, the problems of origin (ethnogenesis), settlement (ethnography) and cultural and historical relationships between peoples. It took shape as a science in the 19th century with the emergence of the evolutionary school, the appearance of research by L. G. Morgan and the book by F. Engels “The Origin of the Family, Private Property and the State” (1884), which formulated the foundations of the doctrine of the primitive communal system. Great merits in the development of ethnology in Russia belong to N. N. Miklukho-Maclay, M. M. Kovalevsky, and D. N. Anuchin. Ethnology is an emerging science. The need for it arose only in the second half of the 20th century, when it became clear that the simple accumulation of ethnographic collections and observations threatens that science, which does not pose problems, will turn into meaningless collecting. And so social science and ethnology arose before our eyes - two disciplines that are interested in one, at first glance, subject - a person, but in completely different aspects. And this is natural. Each person is simultaneously a member of society and a member of an ethnic group, and this is far from the same thing.

Mankind, which has existed on Earth for a very short time, some 30-50 thousand years, nevertheless, made upheavals on its surface, which V. I. Vernadsky equated with small-scale geological upheavals. This problem is relevant for our generation, and it will become especially relevant for our descendants. Man as a biological being belongs to the genus Homo. This genus, when it appeared on Earth, was characterized by a rather large diversity of species. This also applies to those types of Homo, which we, strictly speaking, have no right to consider as people, namely: Pithecanthropes and Neanderthals. Ethnicity in humans is the same as prides in lions, packs in wolves, herds in ungulates. This is a form of existence of the species Homo sapiens and its individuals, which differs both from social formations and from purely biological characteristics, which are races.

In the number of races, the opinions of anthropologists disagree - four or six. Both in appearance and in psychophysical characteristics, representatives of different races are very different from each other. Race is a relatively stable biological characteristic of the species of people, but it is by no means a form of their hostel, a way of their life together. Races differ in purely external features, which can be determined anatomically. Just as an ethnos does not coincide with a race, it does not coincide with another biological grouping of individuals - a population. Population - the sum of individuals living in the same area and randomly interbreeding with each other. There are always marriage restrictions in an ethnic group. Two ethnic groups can coexist on the same territory for centuries and millennia. They can mutually destroy each other or one will destroy the other. This means that ethnos is not a biological phenomenon, just as it is not a social one. “That is why I propose to consider ethnos as a geographical phenomenon,” wrote the Russian ethnologist S. Lurie, “always associated with the enclosing landscape that feeds the adapted ethnos.” And since the landscapes of the Earth are diverse, ethnic groups are also diverse.

The dependence of a person on the nature around him, more precisely, on the geographical environment, has never been disputed, although the degree of this dependence was assessed differently by different scientists. But, in any case, the economic life of the peoples inhabiting and inhabiting the Earth is closely connected with the landscapes and climate of the inhabited territories. The rise and fall of the economy of ancient eras is rather difficult to trace because of the inferiority of information obtained from primary sources. But there is an indicator - military power.

The significance of geographical conditions, for example, relief for military history, has been discussed for a long time, one might say, always. However, dwelling on such a clear problem in the 20th century is inappropriate, because history now poses much deeper tasks than before, and geography has moved away from a simple description of the curiosities of our planet and has gained opportunities that were inaccessible to our ancestors.

So the question is different. Not only how does the geographic environment affect people, but also to what extent people themselves are an integral part of that shell of the Earth, which is now called the biosphere. Which patterns of human life are influenced by the geographic environment and which ones are not affected? This formulation of the question requires analysis. Speaking of the history of mankind, they usually have in mind the social form of the movement of history, that is, the progressive development of mankind as a whole in a spiral. This movement is spontaneous and because of this alone it cannot be a function of any external causes whatsoever. Neither geographic nor biological influences can influence this side of history. So what do they affect? on organisms, including humans. This conclusion was made already in 1922 by the outstanding Russian physiogeographer Lev Berg for all organisms, including humans: “The geographical landscape affects organisms, forcing all individuals to vary in a certain direction, as far as the organization of the species allows. Tundra, forest, steppe, desert, mountains, aquatic environment, life on islands, etc. - all this leaves a special imprint on organisms. Those species that fail to adapt must move to a different geographical landscape or become extinct.” And by "landscape" is meant "a section of the earth's surface, qualitatively different from other areas, bordered by natural boundaries and representing a holistic and mutually conditioned natural set of objects and phenomena, which is typically expressed over a significant space and is inextricably linked in all respects with the landscape shell." Berg in his writings formulated the evolutionary concept of nomogenesis as a process proceeding according to certain internal patterns, not reducible to the effects of the external environment. Unlike Darwin, Berg believed that hereditary variability is regular and ordered (for example, by homological series), and natural selection does not drive evolution, but only "guards the norm." He also believed that all living things are inherent in the original expediency (as Aristotle thought when building his ladder of beings) of reactions to the influence of the external environment, while development takes place due to some force independent of the environment, directed towards the complication of biological organization. In our time, the ideas of nomogenesis were developed by the outstanding Russian biologists A. A. Lyubishchev and S. V. Meyen.

Variability - the property of organisms to acquire new signs and characteristics of individual development under the influence of the environment. Distinguish between modification and genotypic variability.

Modification variability is the ability of an organism to respond to environmental conditions, to change within the normal range of the organism's reaction.

Hereditary variability is the ability to change the genetic material itself.

In all forms of variability, there is genetic control, and the changes that have occurred can only be judged by the phenotype (by changes in the signs and properties of the organism).

Modifications develop in the natural environment and are exposed to factors encountered many times in the process of phylogenesis, that is, the reaction norm has developed historically.

Modifications that resemble manifestations of mutations in known genes are called phenocopies. They are similar to mutations, but the mechanism of their occurrence is different (cataract can be the result of both a mutation and a phenocopy).

Modifications have an adaptive value and contribute to the adaptation of the body to environmental conditions, maintain the homeostasis of the body.

The study of modification variability is carried out using the twin method (the relative role of heredity and environment in the development of a trait) and the method of variation statistics (the study of quantitative traits).

Genotypic variability is associated with qualitative and quantitative changes in the hereditary material. It includes combinative and mutational variability.

1. Combinative variability. The uniqueness of each genotype is due to combinative variability, which is determined by new combinations of gene alleles in the genotype. This is achieved as a result of 3 processes: two of them are associated with meiosis, the third - with fertilization.

2. Mutational variability. With mutational variability, the structure of the genotype is disturbed, which is caused by mutations. Mutations are qualitative, sudden, persistent changes in the genotype.

There are various classifications of mutations.

By the level of changes in hereditary material (gene, chromosomal, genomic);

By manifestation in the phenotype (morphological, biochemical, physiological);

By origin (spontaneous, induced);

According to their influence on the life of the organism (lethal, semi-lethal, conditionally lethal);

By cell types (somatic and generative);

By localization in the cell (nuclear, cytoplasmic).

Gene mutations are associated with a DNA molecule - a violation of the normal nucleotide sequence characteristic of a given gene. This can be caused by a change in the number of nucleotides (deletion or insertion) or by their replacement.

Mutations appear in the genotype with a certain frequency and often manifest themselves phenotypically. Some of them are the cause of gene (molecular) diseases. The body has mechanisms that limit the adverse effect of mutations: DNA repair, diploid set of chromosomes, degeneracy of the genetic code, repetition (amplification) of some genes.

Chromosomal mutations (aberrations) consist in changes in the structure of chromosomes (intrachromosomal and interchromosomal).

Intrachromosomal mutations: deletions, duplications, inversions. With deletions and duplications, the amount of genetic material changes, and with inversions, its location. With interchromosomal mutations, the translocation of hereditary material occurs, the exchange of sites between non-homologous chromosomes.

Genomic mutations consist in a change in the number of individual chromosomes (heteroploidy) or a violation of the genomic number of chromosomes (polyploidy).

Chromosomal and genomic mutations are the causes of chromosomal diseases. A mutation notation system has been developed (Denver and Paris classification).

Mutations are important in onto- and phylogenesis, they lead to the emergence of new properties of the hereditary material: gene mutations - the emergence of new alleles, chromosomal aberrations - to the formation of new gene linkage groups, genomic mutations - new genotypes. They provide the phenotypic diversity of organisms.

Mutagenesis (mutation process)

Mutation process - the process of occurrence, formation and implementation of hereditary disorders. Mutations are the basis of the mutation process. Mutations occur both in the natural habitat of organisms and under conditions of directed exposure to mutagens. Depending on this, spontaneous and induced mutagenesis are distinguished.

Spontaneous mutagenesis is a spontaneous process of the occurrence of mutations under the influence of natural environmental factors. There are several hypotheses regarding the genesis of spontaneous mutations: natural radiation, the presence of mutator genes, a certain ratio of mutagens and antimutagens, etc. According to modern data, mutations occur when the process of DNA replication and repair is disrupted.

Spontaneous mutation process is characterized by a certain intensity (frequency of gene, chromosomal and genomic mutations), continuity, non-direction, lack of specificity; it is one of the biological characteristics of the species (genotype stability) and proceeds constantly. The frequency of spontaneous mutations is subject to gene control (repair enzymes) and in parallel to the influence of natural selection (the appearance of new mutations is balanced by their elimination). Knowledge of the patterns of spontaneous mutagenesis, the reasons for its occurrence is necessary to create special methods for tracking mutations in order to control their number in humans.

Induced mutagenesis - the occurrence of mutations under the influence of directed special environmental factors - mutagens.

The ability to induce mutations is possessed by various mutagens of a physical, chemical, and biological nature, which cause, respectively, radiation, chemical, and biological mutagenesis.

Physical mutagens: ionizing radiation, ultraviolet, temperature, etc. Ionizing radiation has a direct effect on genes (breaking DNA hydrogen bonds, changing nucleotides), chromosomes (chromosomal aberrations) and genomes (changing the number and sets of chromosomes). The effect of radiation is reduced to ionization and the formation of free radicals. Different forms of living organisms are characterized by different sensitivity to radiation.

Chemical mutagens (drugs, nicotine, alcohol, herbicides, pesticides, acids, salts, etc.) cause gene, rarely chromosomal, mutations. The mutagenic effect is greater for those compounds that are able to interact with DNA during the replication period.

Biological mutagens (viruses, live vaccines, etc.) cause gene mutations and chromosomal rearrangements. The mutagenic effect is selective for individual genes.

When assessing induced mutations, individual and population prognosis are taken into account. All types of mutagenesis are dangerous when large populations of people are involved.

To protect living organisms from the damaging effects of mutagens, antimutagens are used, and an integrated system of genetic monitoring and chemical screening is organized.

Repair of genetic material

DNA is highly stable, which is maintained by a special enzymatic system under genetic control; it also takes part in repair. Many DNA damages that could be realized as mutations under the action of strong mutagens are corrected by reparative systems.

Genetic differences in the activity of repair enzymes determine different life spans and resistance of organisms to the action of mutagens and carcinogens. In humans, some diseases (progeria) are associated with a violation of the process of DNA replication and repair. A model for studying the genetic mechanisms of repair is a disease - xeroderma pigmentosa. It is known that 90% of mutagens are also carcinogens. There are several theoretical concepts (theories) of carcinogenesis: mutational, viral-genetic, oncogene concept, etc.

Genetic monitoring

A person comes into contact with a variety of chemicals, it is not possible to check each for the possibility of a mutagenic (carcinogenic) effect or genotoxicity, therefore, certain chemicals are selected for testing for mutagenicity.

The choice of one or another substance is determined by:

Its distribution in the human environment and contact with them by the majority of the population (drugs, cosmetics,

food, pesticides, etc.)

Structural similarity to known mutagens and carcinogens (nitroso compounds, aromatic hydrocarbons) For testing for mutagenicity

Several test systems are used (about 20 out of 100 available methods). there is no universal test to detect all types of mutations in germ and somatic cells.

Stepwise testing is used (at the beginning on microorganisms, Drosophila and other objects, and only then in human cells.)

Sometimes it is enough to use one test system to detect the mutagenicity of a substance and, accordingly, the impossibility of its use.

Genetic monitoring is a system of long-term population studies to control the mutational process in humans (mutation tracking). It is made up of:

Chemical screening - experimental verification of the mutagenicity of chemical compounds (tracking mutations in test systems)

Direct analysis of gene mutation frequencies

Phenogenetic monitoring.

The testing system consists of a sieving and full program, the possibility of their use is determined by the degree of exposure of the population to a given chemical.

Molecular mechanisms of mutations

Mutations. mutation theory. Mutagens

A Brief History of the Study of Mutagenesis

Modern ideas about mutations were formed by the beginning of the 20th century. For example, the Russian botanist Sergei Ivanovich Korzhinsky in 1899 developed an evolutionary theory of heterogenesis based on the concept of the leading role of discrete (discontinuous) changes.

However, the most famous mutation theory Dutch botanist Hugo (Hugo) De Vries (1901):

1 Mutations occur suddenly, without any transitions.

2 Mutant forms are quite stable.

3 Mutations are characterized by discreteness (discontinuity); these are qualitative changes that do not form continuous series, are not grouped around an average type (mode).

4 Mutations occur in different directions, they can be harmful and beneficial.

5 Success in detecting mutations depends on the number of individuals analyzed.

6 The same mutations can occur repeatedly.

Thus, mutations are qualitative changes in the genetic material, leading to a change in certain signs of the organism .

An organism in which a mutation is found in all cells is called mutant. This occurs if the given organism develops from a mutant cell (gametes, zygotes, spores). In some cases, the mutation is not found in all somatic cells of the body; such an organism is called genetic mosaic. This happens if mutations appear during ontogenesis - individual development. And, finally, mutations can occur only in generative cells (in gametes, spores, and in cells of the germ line - precursor cells of spores and gametes). In the latter case, the organism is not a mutant, but some of its descendants will be mutants.

Subsequently, the mutational theory of De Vries was supplemented by a number of provisions. It has been established that different mutations can occur in the same gene: then series of multiple alleles. For example, in the Drosophila fly, the gene white(“white” - white), which determines the color of the eyes, is represented by sequentially dominant alleles: w+(dark red eyes) > w ch(cherry) > w a(apricot) > w bf(dull yellow) > w(white), etc. In rabbits, the gene that determines the severity of albinism is represented by consistently dominant alleles: C(normal, non-albinistic coloration) > c ch(chinchilla) > c h(ermine) > with(complete albinism).

At the same time, mutations with a similar phenotypic effect can occur in different genes. Such mutations are called genocopies. Genocopies must be taken into account in the breeding process: for example, mutations in different genes can cause resistance to phytopathogenic fungi in different plant varieties.

Numerous studies have shown that mutations are not adaptive in nature, they are random, not directed. Only in the course of evolution, in the course of selection, is the "usefulness", "neutrality" or "harmfulness" of mutations under certain conditions evaluated.

It has been established that the mutability of a gene (i.e., the frequency of occurrence of a certain mutation) depends on the nature of the gene: there are genes that are prone to mutation and relatively stable genes. Back in the late 1920s, A. Sturtevant and then N. I. Shapiro proposed, based on the study of Drosophila, to consider mutability as an adaptive trait of the species.

The mutation theory of De Vries is based on ideas about spontaneous mutations that occur for no apparent reason. De Vries did not try (and could not) uncover the mechanisms of mutations.

The study of the molecular mechanisms of the occurrence of mutations is inextricably linked with the study of mutagenesis. (Mutagenesis is the process of obtaining induced mutations with the help of mutagens.)

For the first time, induced mutations were obtained by domestic geneticists G.A. Nadson and G.S. Filippov in 1925 when yeast was irradiated with radium radiation. In 1927, the American geneticist H. Möller revealed the mutagenic effect of X-rays on Drosophila, and in 1928, L. Stadler described the mutagenic effect of X-rays on barley.

In the 1930s discovered chemical mutagenesis. In 1932 V.V. Sakharov, and in 1934 M.E. Lobashev and F.A. Smirnov showed that some chemicals (iodine, acetic acid, ammonia) are capable of inducing mutations in Drosophila. In 1939 S.M. Gershenzon found that pure DNA is a strong mutagen. During the 1940s it was proved that a wide variety of substances can be strong mutagens: ethyleneimine (I.A. Rapoport, USSR), nitrogen mustard (Sh. Auerbach and J. Robson, Great Britain).

In parallel, it was found that mutagens, under certain conditions, have carcinogenic and teratogenic action.

(Carcinogens are factors that provoke the development of oncological diseases; teratogens are factors that provoke the development of various anomalies, deformities. Along with teratami- deformities - often found morphoses- changes that do not lead to the loss of the body of its functions.)

Distinguishing mutagenic from teratogenic is relatively easy: terats (deformities) are modifications, they are predictable (directed) and do not persist in subsequent generations. For example, the gray color of the body in Drosophila is a normal sign. At the same time, the mutation yellow- yellow body. This mutation can be easily obtained artificially by treating parental individuals with different mutagens (note that different mutagens can produce the same phenotypic effect). If Drosophila larvae are fed with silver nitrate, then all these larvae will develop into flies with a yellow body. But, if offspring are obtained from these yellow flies and grown on a normal nutrient medium, then all the offspring will again become gray. Thus, in this case, the "yellowing" of the body of flies is not a mutation, but a modification, or a phenocopy (a modification that copies the mutation in phenotype).

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One of the central questions of modern natural science, to which science does not give an unambiguous answer, is the question of the appearance of man on Earth. The branch of natural science is engaged in the study of the origin and evolution of man, the driving forces and patterns of anthropogenesis, the relationship between biological and social in the process of human development. anthropology(from Greek. anthropos- Human). Currently, there are several concepts of the origin of man.

1. The concept of creationism. In ancient myths and legends of different peoples, ideas about the divine origin of man were reflected, according to which the almighty god (gods) created the world around and man. Often, myths say that the ancestors of man were various animals: the inhabitants of the forest - wolves, bears; the inhabitants of Primorye have walruses or fish. Religious teachings point to the divine origin of man. The dominant religion in European countries - Christianity - recognizes the creator of the world and man as one God, who created man on the sixth day of the creation of the world in his own image and likeness.

2. The concept of evolution. Attempts to determine the position of man in nature, to explain his resemblance to other animals, took place already in the writings of ancient philosophers. Carl Linnaeus in 1735, creating his classification of the organic world, places man in the order of primates along with the lemur and monkey. The idea of ​​kinship between higher primates and humans found support and scientific justification in the works of J. B. Lamarck (1809),

J. Buffon (1749). The largest contribution to the development simial(monkey) theory of anthropogenesis was the book of Ch. Darwin "The Origin of Man and Sexual Selection" (1871), which puts forward a hypothesis about the origin of man from an ape-like ancestor, predicts future fossil finds, emphasizes the special similarity of man, chimpanzee and gorilla, and assumes that the homeland Africa was the first people. Later, discoveries in the field of comparative anatomy, physiology, biochemistry, and genetics provided a number of evidence of human kinship with higher primates. The remains of the common ancestors of humans and great apes found by paleontologists confirmed the correctness of the concept of anthropogenesis.

3. Labor concept. Friedrich Engels in his work "The role of labor in the process of transformation of apes into humans" considers the features of the evolution of primates associated with labor activity. An essential moment in the process of anthropogenesis is upright posture, which caused the intensive development of the nervous system, especially the brain. Thanks to upright posture, the functions of the upper and lower extremities were separated, an unspecialized hand was formed - a tool capable of producing hundreds of various and subtle movements. Joint labor activity in difficult conditions helped people to survive and cope with numerous threats of the surrounding world, to create their own world, comfortable and safe. Labor was a prerequisite for the emergence and further development of social relations, speech, thinking, consciousness - everything that distinguishes a person from an animal. Man is the only creature on Earth capable of consciously and purposefully transforming the world around him, planning and foreseeing results. Gradually, the biological factors of human evolution give way to social factors.

4. The concept of mutagenesis. At the end of the 20s. 20th century researchers came to the conclusion that speciation cannot be explained only by changes in environmental conditions (S. S. Chetverikov, R. A. Fisher, N. P. Dubanin, and others). The dominant role in evolution should be played by dominant mutations- changes in the genetic code of an individual. The conditions of the environment and way of life contribute only to natural selection among the many mutations of individuals, which differ in some advantage, better adaptation to given conditions. The reason for the occurrence of this kind of mutation, as scientists suggest, may be extreme geophysical factors, such as a change radiation level or geomagnetic inversion. Scientists have found that the place of origin of anthropoids is East and South Africa, characterized by a high level of radiation and active volcanic activity. As a result of earthquakes, the displacement of geological layers caused the exposure of radioactive rocks and a sharp increase in radioactive radiation, which led to intense mutagenesis. Coincidence with these processes geomagnetic inversion made possible the emergence of a variety of genetic mutations, including biologically beneficial ones. The hypothesis of geomagnetic inversion (change of the Earth's magnetic poles) was put forward by the anthropologist G. N. Matyushkin. It has been established that the north and south magnetic poles of the Earth periodically change, while the protective function of the magnetosphere weakens, which increases the penetration of cosmic radiation to the Earth's surface by 60%. Geomagnetic reversals are accompanied by a doubling of the mutation frequency, and this leads to powerful bursts of biological morphogenesis. Anthropologists attribute the remains of ancient ape-men found in Africa to the period of geomagnetic inversion, the appearance of Pithecanthropus also coincides in time with the next geomagnetic inversion (690 thousand years ago). The next change of poles occurred 250-300 thousand years ago, at the same time Neanderthals existed on Earth. The appearance of modern man (30–40 thousand years ago) also coincides with the period of the next geomagnetic inversion.

5. Space concept, panspermia concept. Life originated in space and was brought to Earth in the form of cosmic rudiments - cosmozoans (Richter G., 1865). The space concept was supported by Russian scientists S. P. Kostychev, L. S. Berg, V. I. Vernadsky, linking the emergence of life with the appearance on Earth of particles of matter, dust particles, spores from outer space that fly in the Universe due to light pressure.

In the late 1960s thanks to the successes of astronautics, the study of unidentified flying objects (UFOs), the description of rock paintings, interest in the hypotheses of panspermia arose again. Thus, B. I. Chuvashov (1966) wrote that life in the Universe exists forever and can be transferred from one planet to another.

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Mutagenesis -

the process of occurrence of hereditary changes - mutations that appear naturally (spontaneously) or caused (induced) by various physical or chemical factors - mutagens.

Mutations

- these are qualitative changes in the genetic material, leading to a change in certain signs of the organism. lip augmentation with hyaluronic acid

An organism in which a mutation is found in all cells is called a mutant. This occurs if the given organism develops from a mutant cell (gametes, zygotes, spores). In some cases, the mutation is not found in all somatic cells of the body; such an organism is called a genetic mosaic. This happens if mutations appear during ontogenesis - individual development. And, finally, mutations can occur only in generative cells (in gametes, spores, and in cells of the germ line - precursor cells of spores and gametes). In the latter case, the organism is not a mutant, but some of its descendants will be mutants.

Mutagenesis is based on changes in nucleic acid molecules that store and transmit hereditary information. These changes are expressed as gene mutations or chromosomal rearrangements. In addition, disturbances in the mitotic apparatus of cell division are possible, which leads to genomic mutations such as polyploidy or aneuploidy. Damage to nucleic acids (DNA, RNA) consists either in violations of the carbohydrate-phosphate backbone of the molecule (its rupture, insertion or loss of nucleotides), or in chemical changes in nitrogenous bases that directly represent gene mutations or lead to their appearance during the subsequent replication of the damaged molecule. In this case, the purine base is replaced by another purine base or the pyrimidine base is replaced by another pyrimidine base (transitions), or the purine base is replaced by a pyrimidine base or the pyrimidine base is replaced by a purine base (transversions). As a result, two types of disorders occur in the nucleotide triplets (codons) that determine protein synthesis: the so-called nonsen codons ("meaningless"), which do not determine the inclusion of amino acids in the synthesized protein at all, and the so-called missense codons ("meaning-distorting"), which determine the inclusion of the wrong amino acid in the protein, which changes its properties. Insertions or deletions of nucleotides lead to misreading of genetic information (reading frame shift), which usually results in “meaningless” codons and only in rare cases “meaning-distorting” codons.

Mutations do not occur instantly. Initially, under the influence of mutagens, a pre-mutation state of the cell occurs. Various repair systems seek to eliminate this condition, and then the mutation does not occur. The basis of repair systems are various enzymes encoded in the genotype of the cell (organism). Thus, mutagenesis is under the genetic control of the cell; it is not a physico-chemical, but a biological process.

For example, enzymatic repair systems cut out a damaged section of DNA if only one strand is damaged (this operation is performed by endonuclease enzymes), then a DNA section is completed again that is complementary to the remaining strand (this operation is performed by DNA polymerases), then the restored section is sutured to the ends. threads remaining after cutting out the damaged area (this operation is performed by ligases).

There are also more subtle mechanisms of reparation. For example, with the loss of a nitrogenous base in a nucleotide, its direct incorporation occurs (this applies to adenine and guanine); the methyl group can simply be cleaved off; single strand breaks are sewn together. In some cases, more complex, little-studied repair systems operate, for example, when both strands of DNA are damaged.

However, with a large number of DNA damages, they can become irreversible. This is due to the fact that: firstly, repair systems may simply not have time to correct damage, and secondly, the enzymes of repair systems themselves may be damaged, irreversible DNA damage leads to the appearance of mutations - persistent changes in hereditary information.

The mechanism of mutagenesis for different mutagens is not the same. Ionizing radiation acts directly on nucleic acids, ionizing and activating their atoms. This leads to breaks in the carbohydrate-phosphate backbone of the molecule and hydrogen bonds between complementary DNA strands, the formation of "crosslinks" between these strands, and the destruction of nitrogenous bases, especially pyrimidine ones. The direct effect of ionizing radiation on chromosomes and the DNA contained in them causes an almost linear relationship between the radiation dose and the frequency of radiation-induced gene mutations and shortages (small divisions); however, for those types of chromosomal rearrangements that arise as a result of two chromosome breaks (larger deletions, inversions, translocations, etc.), the relationship between the radiation dose and their frequency is more complex. The mutagenic effect of ionizing radiation can also be indirect, since their passage through the cytoplasm or nutrient medium in which microorganisms are cultivated causes water radiolysis and the appearance of free radicals and peroxides that have a mutagenic effect. Ultraviolet radiation excites the electron shells of atoms, which causes various chemical reactions in nucleic acids, leading to mutations. Of these reactions, the hydration of cytosine and the formation of thymine dimers are of greatest importance, but the breaking of hydrogen bonds between DNA strands and the formation of "crosslinks" between these strands also play a known role in mutagenesis. Ultraviolet rays do not penetrate well into the internal tissues of the body, and their mutagenic effect is manifested only where they can reach the genetic apparatus (for example, when irradiating viruses, bacteria, plant spores, etc.). The most mutagenic are ultraviolet rays with a wavelength of 2500 to 2800 A absorbed by nucleic acids. Visible spectrum rays suppress the mutagenic effect of ultraviolet rays. Alkylating compounds, which include the most powerful known mutagens (the so-called supermutagens), for example, nitrosoethylurea, ethylmethanesulfonate, etc., alkylate the phosphate groups of nucleic acids (which leads to breaks in the carbohydrate-phosphate backbone of the molecule), as well as nitrogenous bases (mainly guanine), as a result of which the accuracy of nucleic acid replication is disturbed and transitions and occasionally transversions occur. Analogues of nitrogenous bases are included in nucleic acids, which, during subsequent replication, leads to the appearance of transitions and transversions. The same types of changes are caused by nitrous acid, which deaminates nitrogenous bases. Acridine dyes form a complex with DNA that interferes with its replication: as a result, one or more pairs of nucleotides are dropped or additionally inserted, which leads to a shift in the reading frame. Similar types of reactions with nucleic acids also characterize other chemical mutagens, but for many of them the mechanism of mutagenesis is not well understood.

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