Evolution is the theory of evolution of the organic world. Evolution of the organic world (from the Cambrian to the present, the origin of life, growth), Darwinism

Evolution (from Latin evolutio - deployment), in a broad sense - a synonym for development; processes of change (primarily irreversible) occurring in animate and inanimate nature, as well as in social systems. Evolution can lead to complication, differentiation, an increase in the level of organization of the system (progress) or, conversely, to a decrease in this level (regression). In a narrow sense, the concept of evolution includes only gradual quantitative changes, opposing it to development as a qualitative shift, that is, revolution. In real development processes, revolution and evolution (in the narrow sense) are equally necessary components and form a contradictory unity.

Evolution in the broad sense of the word refers to the gradual change of complex systems over time. They talk about the evolution of stars and galaxies, landscapes and biocenoses, languages and social systems.

Biological evolution is a hereditary change in the properties and characteristics of living organisms over a number of generations. In the course of biological evolution, an agreement is achieved and constantly maintained between the properties of living organisms and the conditions of the environment in which they live. Since conditions are constantly changing, including as a result of the vital activity of the organisms themselves, and only those individuals that are best adapted to life in changed environmental conditions survive and reproduce, the properties and signs of living beings are constantly changing. The conditions of life on Earth are infinitely diverse, so the adaptation of organisms to life in these different conditions has given rise in the course of evolution to a fantastic variety of life forms.

Driving forces of evolution, their relationship.

1. The teachings of Ch. Darwin about the driving forces of evolution. Driving forces of evolution: hereditary variability, struggle for existence, natural selection.

2. Hereditary variability. The reason for hereditary changes is a change in genes and chromosomes, a recombination (combination) of parental traits in offspring. Beneficial, harmful and neutral hereditary changes. Random, undirected nature of hereditary changes. The role of hereditary variation in evolution: the supply of material for the action of natural selection.

4. Forms of struggle for existence:

Fight against unfavorable conditions of inanimate nature (abiotic factors). Influence on any organism of unfavorable conditions: excess or lack of moisture, light, high or low air temperature. Example: death or oppression of individuals of a light-loving plant in low light conditions;

Intraspecific struggle for existence - the relationship between individuals of the same species. The greatest intensity of intraspecific struggle due to the similarity of needs in individuals of the same species (the need for similar food, lighting, soil, etc.).

5. Natural selection - the process of survival of individuals with hereditary changes that are useful in given environmental conditions and their subsequent reproduction. Selection is a consequence of the struggle for existence, the main factor of evolution, preserving individuals mainly with hereditary changes that are useful in certain environmental conditions. The selecting factor is environmental conditions: high or low air temperature; excess or lack of moisture, light, food.

6. The mechanism of action of natural selection:

The appearance of hereditary changes in individuals (beneficial, harmful, neutral);

Preservation as a result of the struggle for existence, natural selection, predominantly individuals with hereditary changes that are useful in given environmental conditions;

Reproduction of individuals with useful changes, increase in their number;

Preferential survival of individuals with changes corresponding to the environment among the offspring, their reproduction and transmission of useful changes to a part of the offspring;

Distribution of hereditary changes useful in given environmental conditions.

7. The relationship of the driving forces of evolution. Heterogeneity of individuals of a species due to hereditary variability, supplying material for the action of the struggle for existence and for natural selection. Exacerbation of relationships between individuals as a result of the struggle for existence. Preservation of individuals predominantly with beneficial hereditary changes by natural selection as a consequence of the struggle for existence.

It is important to note that Charles Darwin laid the foundations of the scientific theory of evolution. As the dominant evolutionary doctrine, Darwinism existed from 1859 to 1900, i.e. before the rediscovery of G. Mendel's laws. Until the end of the 20s of the current century, genetic data were opposed to evolutionary theory, hereditary variability (mutational, combinative) was considered as the main factor in evolution, natural selection was assigned a secondary role. Thus, already in the initial period of its formation, genetics was used to create new concepts of evolution. In itself, this fact is significant: it testified to the close connection of genetics with evolutionary theory, but the time for their unification was yet to come. Various kinds of criticism of Darwinism were widespread until the emergence of STE.

An exceptional role in the development of evolutionary theory was played by population genetics, which studies microevolutionary processes in natural populations. It was founded by outstanding domestic scientists S.S. Chetverikov and N.V. Timofeev-Resovsky.

The unification of Darwinism and genetics, which began in the 1920s, contributed to the expansion and deepening of the synthesis of Darwinism with other sciences. The 1930s and 1940s are considered to be the period of formation of the synthetic theory of evolution.

In Western countries, the renewed Darwinism, or the synthetic theory of evolution, gained wide recognition among scientists already in the 40s, although there have always been and are some major researchers who take anti-Darwinian positions.

The main provisions of the STE are derived as a consequence of the Hardy-Weinberg law. It is known that understanding the essence and meaning of the law causes difficulty for schoolchildren, although its mathematical apparatus is simple and accessible to everyone who is familiar with high school algebra. It is important to focus students' attention not only on determining the law of gene frequency and genotypes in a population do not change in a number of generations - its conditions are an infinitely large population, random free crossing of individuals, the absence of a mutation process, natural selection and other factors - the mathematical model AA p2 + Aa 2 p + aaq2 = 1, but also on the practical application of the law.

Modern science has very many facts proving the existence of the evolutionary process. These are data from biochemistry, genetics, embryology, anatomy, taxonomy, biogeography, paleontology and many other disciplines. The main evidence to date is:

taxonomy data reflecting the course of evolutionary transformations;

embryological evidence obtained in the study of the development of chordate embryos, confirming the validity of the law of germinal similarity of K. Baer. In addition, it was shown that in the course of its individual development, an organism passes through stages that reflect the phylogeny of a given species. Based on these data, the biogenetic law was formulated (F. Muller, E. Haeckel);

cellular structure;

comparative anatomy data;

data obtained during selection work;

evidence of the existence of natural selection in nature (melanization of insects);

universality of the genetic code;

the unity of the organization of genetic material and the implementation of genetic information;

the universality of the energy accumulator in a living cell - ATP;

genetic evidence. Phylogenetically close species have similarities in the structure of genes;

similarity in the structure of proteins of organisms belonging to close taxonomic groups;

experimental evidence. Modeling of evolutionary processes on living organisms (models).

Modern ideas about the factors of evolution are the result of the development of Darwinism, genetics and ecology. Charles Darwin in his classic work "The Origin of Species" solved the problem of the main driving forces (factors) of the evolutionary process. He singled out the following factors: heredity, variability and natural selection. In addition, Charles Darwin pointed out the important role of limiting the free interbreeding of individuals due to their isolation from each other, which arose in the process of evolutionary divergence of species.

In the modern view, the factors of the evolutionary process are hereditary variability, natural selection, genetic drift, isolation, migration of individuals, etc. All organisms form natural groups with similar anatomical features of the individuals included in them. Large groups are successively divided into smaller ones, the representatives of which have an increasing number of common features. It has long been known that organisms of a similar anatomical structure are similar in their embryonic development. However, sometimes even significantly different species, such as turtles and birds, are almost indistinguishable in the early stages of individual development. The embryology and anatomy of organisms are so closely correlated with each other that taxonomists (specialists in the field of classification) use the data of both these sciences equally in developing schemes for the distribution of species into orders and families. Such a correlation is not surprising, since the anatomical structure is the end result of embryonic development.

The direction of evolution of each systematic group is determined by the relationship between the features of the environment in which the evolution of a given taxon takes place and its genetic organization, which has developed in the course of its previous evolution.

Divergence. Most often in the course of evolution, we observe divergence or divergence of characters in species descending from a common ancestor. Divergence begins at the population level. It is due to differences in the environmental conditions in which the daughter species live and to which they adapt differently under the influence of natural selection. Genetic drift also plays a certain role in divergence. Divergence causes an increase in the number of species and continues at the level of supraspecific taxa. It is divergent evolution that accounts for the amazing diversity of living beings.

A striking example of divergence is the change in the limbs of mammals in the course of their adaptation to different environmental conditions.

Convergence (convergence of characters) is observed when unrelated taxa adapt to the same conditions. Convergence is spoken of in those cases when an external similarity is found in the structure and functioning of an organ that has completely different origins in the compared groups of living organisms. For example, the wing of a dragonfly and a bat have common features in structure and function, but are formed during embryonic development from completely different cellular elements and are controlled by different groups of genes. Such bodies are called similar. They are outwardly similar, but different in origin, they do not have a phylogenetic commonality. The similarity in eye structure between mammals and cephalopods is another example of convergence. They arose independently in the course of evolution and are formed in ontogeny from different rudiments.

General and private fixtures. Questions about the possible paths of the evolutionary process were developed by A. N. Severtsov. One of the main such ways, according to Severtsov, is aromorphosis (arogenesis), or the emergence in the course of evolution of adaptations that significantly increase the level of organization of living organisms and open up completely new evolutionary possibilities for them. Such adaptations were, for example, the emergence of photosynthesis, sexual reproduction, multicellularity, pulmonary respiration in the ancestors of amphibians, amniotic membranes in the ancestors of reptiles, warm-bloodedness in the ancestors of birds and mammals, etc. Aromorphoses are a natural result of evolutionary processes. They open up opportunities for species to explore new, previously inaccessible habitats.

Aromorphoses do not occur instantly; when they appear, they are practically indistinguishable from ordinary adaptations. Only with their evolutionary "polishing" by natural selection, coordination with numerous signs of the organism and wide distribution in many species, do they become aromorphoses. For example, the appearance of pulmonary respiration in the ancient inhabitants of fresh water did not radically change their lifestyle, level of organization, etc. However, as a result of this adaptation, it became possible to develop land - a vast habitat. This opportunity was actively used in subsequent evolution, many thousands of species of amphibians, reptiles, birds and mammals appeared, filling various habitat niches. Therefore, the acquisition of lungs by vertebrates is a major aromorphosis, which led to an increase in the level of organization of many species.

There are also smaller aromorphoses. There were several of them in the evolution of mammals: the appearance of a coat, live birth, feeding of young with milk, the acquisition of a constant body temperature, the progressive development of the brain, etc. The high level of organization of mammals, achieved due to the listed aromorphoses, allowed them to master new habitats.

In addition to such a major transformation as aromorphosis, in the course of the evolution of individual groups, a large number of small adaptations to certain environmental conditions arise. A. N. Severtsov called such adaptations idioadaptation.

Idioadaptation is the adaptation of organisms to the environment without a fundamental restructuring of the biological organization. An example of idioadaptation is the diversity of forms in insectivorous mammals, different species of which, having a common initial level of organization, were able to acquire properties that allowed them to occupy different habitats in nature.

The paths of evolution of the organic world either combine with each other or replace each other, and aromorphoses occur much less often than idioadaptation. But it is aromorphoses that determine new stages in the development of the organic world. Having arisen by aromorphosis, new, higher in organization groups of organisms occupy a different habitat. Further, evolution follows the path of idioadaptation, and sometimes degeneration, which provide organisms with the development of a new habitat for them.

2. CHANGES IN BASIC INDUSTRIES

With the beginning of the transition to a post-industrial society, the share of industry in world GDP and employment of the economically active population decreases. industry still remains the most important branch of material production. Large investments are directed to industrial production, large expenses for research and development work are associated with it. Manufactured goods retain unconditional primacy in world trade. Industry continues to have a great impact not only on the economy, but also on other aspects of public life. And the territorial structure of industry to the greatest extent determines the territorial structure of the entire world economy, forming, as it were, its framework. Therefore, it is sometimes not without reason continue to be called the engine of economic development.

Big shifts are taking place in the sectoral structure of world industry. At the mesostructure level, they are expressed primarily in a change in the proportion between the extractive and manufacturing industries. Throughout the second half of the twentieth century. there was a steady downward trend in the share of extractive industries in total industrial production; now it is about 1/10. But the changes also affected the internal proportions in the mining and manufacturing industries.

The extractive industry is a whole complex of industries and sub-sectors, which includes not only mining, but also the logging industry. It also includes marine fishing, water supply, hunting and fishing facilities. Approximately 3/4 of the total output of this industry falls on its main sub-sector - the mining industry. In turn, in the structure of the mining industry, 3/5 of the products (by value) are provided by the oil and gas industry, and the rest, in approximately equal shares, by coal and ore mining.

The manufacturing industry is structurally a much more complex complex, including more than 300 different industries and sub-sectors, which are usually divided into four blocks: 1) production of structural materials and chemical products; 2) mechanical engineering and metalworking; 3) light industry; 4) food industry. In the structure of manufacturing industries, heavy and light industries are also distinguished: if in the 60s the ratio between them was 60:40, then in the mid-90s it was already 70:30. The first place in the structure of the world manufacturing industry is occupied by mechanical engineering (40% of all products), the second place is occupied by the chemical industry (more than 15%). This is followed by food (14%), light industry (9%), metallurgy (7%) and other industries. The ratio between them changes somewhat with time, but in general remains relatively stable. On the other hand, the shifts taking place in the structure of each of these industries are usually more noticeable. First of all, this applies to mechanical engineering, as the most diversified branch of industrial production.

The fastest growing branch of world mechanical engineering has been and remains the electronic and electrical industry, whose share in all manufacturing products has already grown to 1/10. The general engineering industry as a whole is characterized by moderate growth, and changes are also taking place in its structure: the production of agricultural, textile machinery and equipment is decreasing, and the production of road transport machines is increasing, and especially robots, office equipment, etc. The share of transport engineering in The structure of the manufacturing industry as a whole remains relatively stable, but this also hides internal differences: the share of shipbuilding and rolling stock is declining, but the share of the automotive industry is generally maintained.

Along with shifts in the sectoral structure of world industry, there are changes in its territorial proportions. Usually these changes are considered at different hierarchical levels, ranging from the comparison of North and South to individual countries.

Exercise

The relic radiation discovered in the 1970s, that is, the microwave background radiation, began to be considered an experimental confirmation of the model: ...?

All species arose in the process evolution and continue to evolve. But there are organisms populations which are so well adapted to their environment that their species features have remained virtually unchanged for tens and hundreds of millions of years. These include the first autotrophs - blue-green algae, the descendants of the first cartilaginous fish - sharks, the same age as dinosaurs - crocodiles. For more than four hundred million years in Africa, South America and Australia, almost unchanged, live fish that can breathe not only with gills, but also through a swim bladder that differs little from real lungs. They are perfectly adapted to the drought, which lasts in those places from 6 to 9 months a year. When the reservoirs dry up, these fish (protopters) hibernate - they fall asleep with their nose up in peculiar holes dug in the muddy bottom, until the rainy season wakes them up. However, in a laboratory experiment, an experimental fish slept for more than 3 years without water and food ... The modern theory of evolution explains the riddles of the appearance of such amazing natural phenomena.

The theme of the lesson is "Modern ideas about the evolution of the organic world."

The basis of these ideas is "The Evolutionary Theory of Charles Darwin". However, Darwin proposed his theory 150 years ago, and since then many important discoveries in population ecology, genetics, and molecular biology have taken place. The most important of them were: the rediscovery of the laws of G. Mendel at the beginning of the 20th century, the introduction of the concept of the gene of V. Johansen, the formulation of the chromosome theory of inheritance by T. Morgan, the mutation theory of G. Fries, the population ideas of S. S. Chetverikov and many others () ( see Fig. 1, 2).

Rice. one

Rice. 2

The first discoveries of genetics, and this is the genetic nature of heredity and the mutational theory, caused a crisis in evolutionary theory. Scientists of that time could not correctly combine these discoveries and the provisions of the theory of evolution. A major breakthrough in the field of evolutionary ideas was the work of the English biologist J. Huxley () - "Evolution - a modern synthesis." It served as an impetus for the formulation of a synthetic theory of evolution. At the moment, the synthetic theory of evolution contains the following provisions:

1. The material for the evolutionary process is mutations, as well as their combinations during the sexual process.

2. The main driving force of evolution is natural selection, which occurs against the background of the struggle for survival.

Excess numbers of individuals are no longer the driving force behind evolution, as Darwin previously suggested.

3. The smallest unit of evolution is the population.

One individual is not capable of reproduction and transmission of its characteristics to offspring, therefore, an individual cannot be considered as a unit of evolution.

4. Evolution is divergent in nature, that is, as a rule, one species gives rise to several other species at once.

5. Evolution is gradual and long lasting.

Speciation is a continuous series of changes in different characters. It is impossible to distinguish the beginning and end of speciation.

6. A species is a collection of populations.

Between populations, gene flow is possible as a result of crossing. When for some reason the flow of genes is interrupted, one speaks of isolation. Isolation leads to the accumulation of differences between populations and, ultimately, to speciation.

7. Macroevolution follows the same path as microevolution.

There are no specific ways of macroevolution that would not be characteristic of microevolution.

8. All taxa are of monophyletic origin.

This means that all species of one taxon have a common ancestor.

9. Evolution has an undirected course, that is, its movement is not subject to any logic whatsoever.

Indeed, completely identical populations that have undergone isolation will develop, as a rule, in completely independent directions.

These provisions of modern evolutionary theory make it possible to explain the diversity of species on Earth. However, there are still many experimental data that contradict these theses. But let's hope that further discoveries will be able to overcome these contradictions.

Experiments of the first evolutionists

Modern synthetic evolutionary theory is based on hundreds of complex genetic and molecular biological experiments. At the same time, it practically does not contradict Darwin's basic theory of evolution in any way. It is completely incomprehensible how one scientist could create this theory 150 years ago without even relying on such concepts as a gene or a chromosome. Darwin's genius lies in the fact that he created his theory based only on the paleontological method and the method of observing wildlife.

Preventing the collapse of Darwinism

Huxley's work - "Evolution - the modern synthesis" practically saved Darwinism from collapse (see Fig. 3). The fact is that in the middle of the century, many scientists were ready to abandon Darwinism, based only on the fact that some experiments contradicted it. However, Huxley was able to prove that these experiments not only did not contradict Darwinism, but, moreover, confirmed it.

Rice. 3

An experiment confirming microevolution

Evolution is practically inaccessible for experiment. The change of generations in living beings lasts for months, years or even decades, so it is simply impossible to trace the evolutionary path of a species. A great success in the field of experiments with evolution was the observation of microorganisms. The fact is that a new generation of E. coli is formed already in 10 - 20 minutes, so a huge number of generations can be accumulated within a few days, weeks or months (see Fig. 4). At this scale, mutations will show up sufficiently to allow their role in natural selection to be assessed. These experiments brilliantly confirmed Darwin's theory of evolution.

Rice. 4

Bibliography

Mamontov S.G., Zakharov V.B., Agafonova I.B., Sonin N.I. Biology. General patterns. - M.: Bustard, 2009.
Pasechnik V.V., Kamensky A.A., Kriksunov E.A. Biology. Introduction to general biology and ecology. Textbook for 9 cells. 3rd ed., stereotype. - M.: Bustard, 2002.
Ponomareva I.N., Kornilova O.A., Chernova N.M. Fundamentals of General Biology. Grade 9: Textbook for students in grade 9. educational institutions / Ed. prof. I.N. Ponomareva. - 2nd ed., revised. - M.: Ventana-Graf, 2005.

Homework

What discoveries were associated with the crisis of Darwinism at the beginning of the 20th century?
Why does classical genetics contradict Darwinism?
Are you convinced by the evolutionist evidence?
What particular theories were united by J. Huxley's synthetic theory of evolution?

Evolution should be understood as a process of long-term, gradual, slow changes leading to fundamental qualitatively new changes (the formation of other structures, forms, organisms and their types).

The appearance of the primitive cell meant the end of the prebiological evolution of the living and the beginning of the biological evolution of life.

The first unicellular organisms that arose on the planet were primitive bacteria that did not have a nucleus, i.e. prokaryotes. They were single-celled non-nuclear organisms. They were anaerobes, since they lived in an oxygen-free environment, and heterotrophs, since they fed on ready-made organic compounds of the "organic broth", i.e. substances synthesized in the course of chemical evolution. Energy metabolism in most prokaryotes occurred according to the type of fermentation. But gradually the "organic broth" as a result of active consumption subsided. As it was exhausted, some organisms began to develop ways to form macromolecules biochemically, inside the cells themselves with the help of enzymes. Under such conditions, the cells that were able to obtain most of the required energy directly from solar radiation turned out to be competitive. The process of chlorophyll formation and photosynthesis proceeded along this path.

The transition of living things to photosynthesis and autotrophic type of nutrition was a turning point in the evolution of living things. The Earth's atmosphere began to "fill up" with oxygen, which was poison for anaerobes. Therefore, many unicellular anaerobes died, others took refuge in anoxic environments - swamps and, eating. They emitted not oxygen, but methane. Still others have adapted to oxygen. Their central exchange mechanism was oxygen respiration, which made it possible to increase the output of useful energy by 10-15 times compared to the anaerobic type of metabolism-fermentation. The transition to photosynthesis was long and ended about 1.8 billion years ago. With the advent of photosynthesis, more and more energy of sunlight was accumulated in the organic matter of the Earth, which accelerated the biological cycle of substances and the evolution of living things in general.

Eukaryotes, that is, single-celled organisms with a nucleus, formed in an oxygen environment. These were already more perfect organisms with photosynthetic ability. Their DNA was already concentrated into chromosomes, whereas in prokaryotic cells, the hereditary substance was distributed throughout the cell. The eukaryotic chromosomes were concentrated in the cell nucleus, and the cell itself was already reproducing without significant changes. Thus, the eukaryotic daughter cell was almost an exact copy of the mother cell and had the same chance of survival as the mother cell.

The subsequent evolution of eukaryotes was associated with the division into plant and animal cells. Such a division occurred in the Proterozoic, when the Earth was inhabited by unicellular organisms.

From the beginning of evolution, eukaryotes developed dually, that is, they had parallel groups with autotrophic and heterotrophic nutrition, which ensured the integrity and significant autonomy of the living world.

Plant cells have evolved in the direction of reducing the ability to move due to the development of a rigid cellulose shell, but in the direction of using photosynthesis.

Animal cells have evolved to increase the ability to move, as well as to improve the way they absorb and excrete processed food.

The next stage in the development of living things was sexual reproduction. It arose about 900 million years ago.

The next step in the evolution of living things took place about 700-800 million years ago, when multicellular organisms appeared with a differentiated body, tissues and organs that perform certain functions. These were sponges, coelenterates, arthropods, etc., belonging to multicellular animals.

Subsequently, many types of animals already existed in the seas of the Cambrian. In the future, they specialized and improved. Among the marine animals of that time were crustaceans, sponges, corals, mollusks, trilobites, etc.

At the end of the Ordovician period, large carnivores, as well as vertebrates, began to appear.

Further evolution of vertebrates went in the direction of jawed fish. In the Devonian, lung-breathing fish began to appear - amphibians, and then insects. The nervous system gradually developed as a result of the improvement of the forms of reflection.

A particularly important stage in the evolution of living forms was the emergence of plant and animal organisms from water to land and a further increase in the number of species of land plants and animals. In the future, it is from them that highly organized forms of life originate. The emergence of plants on land began at the end of the Silurian, and the active conquest of land by vertebrates began in the Carboniferous.

The transition to life in the air required many changes from living organisms and involved the development of appropriate adaptations. He dramatically increased the rate of evolution of life on Earth. Man has become the pinnacle of the evolution of the living.

Ch.Darwin's evolutionary theory.

The idea of a long and gradual change in all kinds of animals and plants was expressed by scientists long before Charles Darwin. Aristotle, the Swedish naturalist C. Linnaeus, the French biologist JLamarck, the contemporary of Charles Darwin, the English naturalist A. Wallace, and other scientists spoke in this spirit at different times.

The undoubted merit of Charles Darwin is not the very idea of evolution, but the fact that it was he who first discovered the principle of natural selection in nature and generalized individual evolutionary ideas into one coherent theory of evolution. In the formation of his theory, Ch. Darwin relied on a large amount of factual material, on experiments and the practice of breeding work to develop new varieties of plants and various breeds of animals.

At the same time, Ch. Darwin came to the conclusion that from the many diverse phenomena of living nature, three fundamental factors in the evolution of living things are clearly distinguished, united by a short formula: variability, heredity, natural selection.

These fundamental principles are based on the following conclusions and observations on the living world - these are:

Variability. It is characteristic of any group of animals and plants, organisms differ from each other in many different ways. In nature, it is impossible to find two identical organisms. Variability is an inherent property of living organisms, it manifests itself constantly and everywhere.

According to Charles Darwin, there are two types of variability in nature - definite and indefinite.

1) A certain variability (adaptive modification) is the ability of all individuals of the same species to respond in the same way to these conditions (food, climate, etc.) under certain specific environmental conditions. According to modern concepts, adaptive modifications are not inherited, and therefore, for the most part, they cannot supply material for organic evolution.

2) Indefinite variability (mutations) causes significant changes in the body in a variety of ways. This variability, in contrast to a certain one, is hereditary in nature, while minor deviations in the first generation increase in subsequent ones. Uncertain variability is also associated with changes in the environment, but not directly, as in adaptive modifications, but indirectly. Therefore, according to Ch. Darwin, it is uncertain changes that play a decisive role in evolution.

The constant population of the species. The number of organisms of each species that are born is greater than the number that can find food and survive; nevertheless, the abundance of each species under natural conditions remains relatively constant.
Competitive relations of individuals. Since more individuals are born than can survive, in nature there is a constant struggle for existence, competition for food and habitat.
Adaptability, adaptability of organisms. Changes that make it easier for an organism to survive in a particular environment give their owners an advantage over other organisms that are less adapted to external conditions and, as a result, die. The idea of "survival of the fittest" is central to the theory of natural selection.
Reproduction of "successful" acquired characteristics in offspring. Surviving individuals produce offspring, and thus "successful", positive changes that made it possible to survive are transmitted to subsequent generations.

The essence of the evolutionary process is the continuous adaptation of living organisms to various environmental conditions and the emergence of more and more complex organisms. Therefore, biological evolution is directed from simple biological forms to more complex forms.

Thus, natural selection, which is the result of the struggle for existence, is the main factor in evolution that directs and determines evolutionary changes. These changes become noticeable, passing through the change of many generations. It is in natural selection that one of the fundamental features of the living is reflected - the dialectic of the interaction between the organic system and the environment.

Undoubted advantages of Charles Darwin's evolutionary theory had some disadvantages. So, she could not explain the reasons for the appearance in some organisms of certain structures that seem useless; many species lacked transitional forms between modern animals and fossils; weak point were also ideas about heredity. Subsequently, shortcomings were discovered concerning the main causes and factors of organic evolution. Already in the 20th century, it became clear that Charles Darwin's theory needed further refinement and improvement, taking into account the latest achievements in biological science. This became a prerequisite for the creation of a synthetic theory of evolution (STE).

Synthetic theory of evolution.

Achievements in genetics in revealing the genetic code, advances in molecular biology, embryology, evolutionary morphology, popular genetics, ecology and some other sciences point to the need to combine modern genetics with Charles Darwin's theory of evolution. Such unification gave rise in the second half of the 20th century to a new biological paradigm - the synthetic theory of evolution. Since it is based on the theory of Charles Darwin, it is called neo-Darwinist. This theory is considered as non-classical biology. The synthetic theory of evolution made it possible to overcome the contradictions between evolutionary theory and genetics. STE does not yet have a physical model of evolution, but is a multifaceted complex doctrine that underlies modern evolutionary biology. This synthesis of genetics and evolutionary doctrine was a qualitative leap both in the development of genetics itself and in modern evolutionary theory. This leap marked the creation of a new center of the system of biological knowledge and the transition of biology to the modern non-classical level of its development. STE is often called the general theory of evolution, which is a combination of evolutionary ideas of Charles Darwin, mainly natural selection with modern research results in the field of heredity and variability.

The main ideas of STE were laid down by the Russian geneticist S. Chetverikov as early as 1926 in his works on popular genetics. These ideas were supported and developed by American geneticists D. Haldane and modern Russian geneticist N. Dubinin.

The reference point of STE is the idea that the elementary component of evolution is not a species or an individual, but a population. It is she who is an integral system of interconnection of organisms, which has all the data for self-development. The selection is subjected not to some individual traits or individuals, but to the entire population, its genotype. However, this selection is carried out by changing the phenotypic traits of individual individuals, which leads to the emergence of new traits when changing biological generations.

The basic unit of heredity is the gene. It is a section of the DNA molecule that determines the development of certain signs of the organism. Soviet geneticist N.V. Timofeev-Resovsky formulated a position on the phenomena and factors of evolution. It is as follows:

Population is an elementary structural unit;

The mutation process is the supplier of the elementary evolutionary material;

Population waves - fluctuations in the population in one direction or another from the average number of its individuals;

Isolation fixes the differences in the set of genotypes and causes the division of the original population into several independent ones;

Natural selection - selective survival with the possibility of leaving offspring by individual individuals that have reached reproductive age.

The course of development of the organic world on earth is being reconstructed by researchers according to paleontological data, as well as according to the accumulated morphological and embryological materials. According to established data, our planet was formed less than 7 billion years ago.

The period of time of the existence of our planet is divided into eras. Eras are further subdivided into periods. At each stage of its development, certain changes took place in organic life on Earth.

1. Pregeological era

During this period, the formation of our planet took place. Formation began about 7 billion years ago and lasted less than 3 billion years. During the period of the birth and formation of the planet, life on Earth was absent.

2. Archean era

During this period, life originated on our planet in the water column of the first seas. By the end of this era, life on Earth existed in the form of fairly primitive forms: unicellular bacteria and algae, and only a small number of multicellular ones.

The evolution of the organic world at this stage has undergone relatively minor changes. In this era, there was a division into branches of development of the animal and plant world, which had previously had a common progenitor - unicellular flagellated organisms.

The division occurred on the basis of nutrition. Primary animals remained heterotrophic organisms, while algae in their development acquired the ability to photosynthesize and became autotrophic organisms.

3. Proterozoic era

In terms of its duration, it is considered one of the longest. In this era, new types of algae appeared, which gradually became the starting point for all groups of plants.

The mass reproduction of these types of algae in this era contributed to the accumulation of oxygen on the planet, which played a decisive role in the evolution of the animal world.

The evolution of the organic world on the planet received a powerful impetus to its development. The animal world in that era went a long way in its development. Along the way, new types of worms and mollusks arose. At the end of the Proterozoic era, the simplest arthropods and non-cranial chordates appeared. The main forms of life during this period existed only in water.

4. Paleozoic era

In this era, major events took place in the development of the organic world. The main one is the emergence of plants and animals on land. Bacteria, algae, and lower forms of fungi were the first on land.

With their appearance on land, soil-forming processes began on the planet. Having reached its zenith in the Carboniferous period, amphibians were forced to give way on land to reptiles.

The most intensive development of reptiles was observed in the Permian period of the Paleozoic era. The evolution of the organic world during this era

was that plants have gone from algae to gymnosperms, and vertebrates from the simplest chordates to reptiles, which are both on land.

One of the branches of invertebrate animals has also developed. In its development, it has gone from the simplest marine arthropods to flying insects.

5. Mesozoic era

According to its time period, it was half shorter than the Paleozoic. The development of the organic world in this era took place at a faster pace.

The evolution of the organic world did not stop only at the development of plants. In the Triassic period, the first mammals appeared among vertebrates, and in the Jurassic period, the first birds.

6. Cenozoic era

This era in the historical development of the planet is more gentle. It was during this era that man appeared on Earth. With the advent of man, there was a change in the nature and direction of the evolution of the organic world on the planet.

In the Cenozoic era, the final victory took place among vertebrate mammals, birds and bony fish. In this era, the development of the highest representatives of the plant and animal world took place in close interaction.

During the Paleogene and Neogene, the modern outline of the continents, oceans and seas on earth was formed. The last period of the Cenozoic era - the anthropogen is named after a person who is the highest form of development of living matter and has the greatest influence on the evolution and development of the organic world.

Initial stages of biological evolution

The appearance of the primitive cell meant the end of the prebiological evolution of the living and the beginning of the biological evolution of life.

The first unicellular organisms that arose on our planet were primitive bacteria that did not have a nucleus, that is, prokaryotes. As already mentioned, these were unicellular non-nuclear organisms. They were anaerobes, because they lived in an oxygen-free environment, and heterotrophs, because they fed on ready-made organic compounds of the "organic broth", that is, substances synthesized during chemical evolution. Energy metabolism in most prokaryotes occurred according to the type of fermentation. But gradually the "organic broth" as a result of active consumption subsided. As it was exhausted, some organisms began to develop ways to form macromolecules biochemically, inside the cells themselves with the help of enzymes. Under such conditions, the cells that were able to obtain most of the required energy directly from solar radiation turned out to be competitive. The process of chlorophyll formation and photosynthesis proceeded along this path.

The transition of living things to photosynthesis and autotrophic type of nutrition was a turning point in the evolution of living things. The Earth's atmosphere began to "fill up" with oxygen, which was poison for anaerobes. Therefore, many unicellular anaerobes died, others took refuge in anoxic environments - swamps and, feeding, emitted not oxygen, but methane. Still others have adapted to oxygen. Their central exchange mechanism was oxygen respiration, which made it possible to increase the yield of useful energy by 10–15 times compared to the anaerobic type of metabolism - fermentation. The transition to photosynthesis was a long process and ended about 1.8 billion years ago. With the advent of photosynthesis, more and more solar energy was accumulated in the organic matter of the Earth, which accelerated the biological cycle of substances and the evolution of living things in general.

Education of plants and animals

Table 8.2

The emergence and distribution of organisms in the history of the Earth (according to Z. Brehm and I. Meinke, 1999)

Since the beginning of evolution, eukaryotes have developed dually, that is, they had parallel groups with autotrophic and heterotrophic nutrition, which ensured the integrity and significant autonomy of the living world.

Plant cells have evolved in the direction of reducing the ability to move due to the development of a rigid cellulose shell, but in the direction of using photosynthesis.

Animal cells have evolved to increase the ability to move, as well as to improve the way they absorb and excrete processed food.

The next stage in the development of living things was sexual reproduction. It originated about 900 million years ago.

Throughout the Proterozoic and at the beginning of the Paleozoic, plants inhabited mainly the seas and oceans. These are green and brown, golden and red algae.

At the end of the Ordovician period, large carnivores, as well as vertebrates, began to appear.

Life in the air has “increased” the body weight of organisms, the air does not contain nutrients, air transmits light, sound, heat differently than water, the amount of oxygen in it is higher. All this had to be adjusted. The first vertebrates to adapt to the conditions of life on land were reptiles. Their eggs were supplied with food and oxygen for the embryo, covered with a hard shell, and were not afraid of drying out.

Approximately 67 million years ago birds and mammals gained the advantage in natural selection. Thanks to the warm-bloodedness of mammals, they quickly gained a dominant position on Earth, which is associated with the conditions of cooling on our planet. At this time, it was warm-bloodedness that became the decisive factor in survival. It provided a constant high body temperature and the stability of the functioning of the internal organs of mammals. The live birth of mammals and the feeding of young with milk was a powerful factor in their evolution, allowing them to reproduce in a variety of environmental conditions. A developed nervous system contributed to a variety of forms of adaptation and protection of organisms.

There was a division of carnivores and ungulates into ungulates and predators, and the first insectivorous mammals laid the foundation for the evolution of placental and marsupial organisms.

The decisive stage in the evolution of life on our planet was the appearance of a detachment of primates. In the Cenozoic, approximately 67–27 million years ago, primates divided into lower and great apes, which are the most ancient ancestors of modern man. The prerequisites for the emergence of modern man in the process of evolution were formed gradually. At first there was a herd way of life. He allowed to form the foundation of future social communication. Moreover, if in insects (bees, ants, termites) biosociality led to the loss of individuality, then in the ancient ancestors of man, on the contrary, it developed the individual traits of the individual. This was a powerful driving force behind the development of the team.

The evolution of life took its next step in the form of the emergence of Homo sapiens (Homo sapiens). It is a reasonable person who has the ability to purposefully change the world around him, create artificial conditions for his habitat and transform the appearance of our planet.

The evolutionary theory of Ch. Darwin

Under evolution (from lat. evolution- development, deployment) should be understood as a process of long-term, gradual, slow changes leading to fundamental qualitatively new changes (the formation of other structures, forms, organisms and their types).

The idea of a long and gradual change in all kinds of animals and plants was expressed by scientists long before Charles Darwin. Aristotle, Swedish naturalist C. Linnaeus, French biologist J. Lamarck, Charles Darwin's contemporary, English naturalist A. Wallace, and other scientists spoke in this spirit at different times.

The undoubted merit of Charles Darwin is not the idea of evolution itself, but the fact that it was he who first discovered the principle of natural selection in nature and generalized individual evolutionary ideas into one coherent theory of evolution. In the formation of his theory, Charles Darwin relied on a large amount of factual material, on experiments and the practice of breeding work to develop new varieties of plants and various breeds of animals.

At the same time, Charles Darwin came to the conclusion that from the many diverse phenomena of living nature, three fundamental factors in the evolution of living things are clearly distinguished, united by a short formula: variability, heredity, natural selection.

These fundamental principles are based on the following conclusions and observations on the living world - these are:

1. Variability. It is characteristic of any group of animals and plants, organisms differ from each other in many different ways. In nature, it is impossible to find two identical organisms. Variability is an inherent property of living organisms, it manifests itself constantly and everywhere.

According to Charles Darwin, there are two types of variability in nature - definite and indefinite.

1) Certain variability(adaptive modification) is the ability of all individuals of the same species in some specific environmental conditions to respond in the same way to these conditions (food, climate, etc.). According to modern concepts, adaptive modifications are not inherited, and therefore, for the most part, they cannot supply material for organic evolution.

2) Uncertain variability(mutation) causes significant changes in the body in a variety of ways. This variability, in contrast to a certain one, is hereditary in nature, while minor deviations in the first generation increase in subsequent ones. Uncertain variability is also associated with changes in the environment, but not directly, as in adaptive modifications, but indirectly. Therefore, according to Ch. Darwin, it is uncertain changes that play a decisive role in evolution.

2. The constant population of the species. The number of organisms of each species that are born is greater than the number that can find food and survive; nevertheless, the abundance of each species under natural conditions remains relatively constant.

3. Competitive relations of individuals. Since more individuals are born than can survive, in nature there is a constant struggle for existence, competition for food and habitat.

4. Adaptability, adaptability of organisms. Changes that make it easier for an organism to survive in a particular environment give their owners an advantage over other organisms that are less adapted to external conditions and, as a result, die. The idea of "survival of the fittest" is central to the theory of natural selection. 5. Reproduction of "successful" acquired characteristics in offspring. Surviving individuals produce offspring, and thus "successful", positive changes that made it possible to survive are transmitted to subsequent generations.

The undoubted advantages of Charles Darwin's evolutionary theory also had some disadvantages. So, she could not explain the reasons for the appearance in some organisms of certain structures that seem useless; many species lacked transitional forms between modern animals and fossils; weak point were also ideas about heredity. Subsequently, shortcomings were discovered concerning the main causes and factors of organic evolution. Already in the XX century. it became clear that the theory of Ch. Darwin needed further refinement and improvement, taking into account the latest achievements of biological science. This became a prerequisite for the creation of a synthetic theory of evolution (STE).

Synthetic theory of evolution

The achievements of genetics in the disclosure of the genetic code, the successes of molecular biology, embryology, evolutionary morphology, popular genetics, ecology and some other sciences indicate the need to combine modern genetics with Charles Darwin's theory of evolution. Such an association gave rise in the second half of the 20th century. new biological paradigm - the synthetic theory of evolution. Since it is based on the theory of Charles Darwin, it is called neo-Darwinist. This theory is considered as non-classical biology. The synthetic theory of evolution made it possible to overcome the contradictions between evolutionary theory and genetics. STE does not yet have a physical model of evolution, but is a multifaceted complex doctrine that underlies modern evolutionary biology. This synthesis of genetics and evolutionary doctrine was a qualitative leap both in the development of genetics itself and in modern evolutionary theory. This leap marked the creation of a new center of the system of biological knowledge and the transition of biology to the modern non-classical level of its development. STE is often called the general theory of evolution, which is a combination of evolutionary ideas of Charles Darwin, mainly natural selection, with modern research results in the field of heredity and variability.

The main ideas of STE were laid down by the Russian geneticist S. Chetverikov as early as 1926 in his works on popular genetics. These ideas were supported and developed by the American geneticists R. Fisher and S. Wright, the English biologist and geneticist D. Haldane, and the contemporary Russian geneticist N. Dubinin (1906–1998).

The main prerequisite for the synthesis of genetics with the theory of evolution were biometric and physical and mathematical approaches to the analysis of evolution, the chromosome theory of heredity, empirical studies of the variability of natural populations, etc.

The reference point of STE is the idea that the elementary component of evolution is not a species (according to Darwin) and not an individual (according to Lamarck), but a population. It is she who is an integral system of interconnection of organisms, which has all the data for self-development. The selection is subjected not to some individual traits or individuals, but to the entire population, its genotype. However, this selection is carried out by changing the phenotypic traits of individual individuals, which leads to the emergence of new traits when changing biological generations.

The basic unit of heredity is the gene. It is a section of a DNA molecule (or chromosome) that determines the development of certain signs of an organism. The Soviet geneticist N. V. Timofeev-Resovsky (1900–1981) formulated a position on the phenomena and factors of evolution. It is as follows:

The main determining factor in the synthetic theory of evolution is natural selection, which directs the evolutionary process. The purely biological significance of an individual as an organism that has given offspring is estimated by its contribution to the gene pool of the population. The objects of selection in a population are the phenotypes of individual individuals. The phenotype of an individual organism is determined and formed on the basis of the genotype information being realized in changing environmental conditions. As a result, from generation to generation, selection for phenotypes leads to the selection of genotypes.

Evolution is a single process. In STE, two levels of evolution are distinguished: microevolution passing at the population-species level in a relatively short time in limited areas, and macroevolution, passing at the subspecies level, where general patterns and trends in the historical development of the living are manifested.

microevolution is a set of evolutionary processes occurring in populations of a species, leading to changes in the gene pools of these populations and to the formation of new species. It occurs on the basis of mutational variability under the strict control of natural selection. Mutations are the only source of qualitatively new traits. Selection is a creative selective factor that directs elementary evolutionary changes along the path of adaptation of organisms to changing environmental conditions. The nature of the processes of microevolution is influenced by changes in the number of populations (waves of life), the exchange of genetic information between them, as well as isolation. Microevolution leads either to a change in the entire gene pool of the species as a whole (phylogenetic evolution), or to their isolation from the parent original species as already new forms (speciation).

macroevolution- these are evolutionary transformations that lead to a change in a higher level of taxa than the species (families, orders, classes). It does not have its characteristic mechanisms and is carried out through the processes of microevolution. Gradually accumulating, microevolutionary processes receive their external expression in the phenomena of macroevolution. Macroevolution is a generalized picture of evolutionary change observed in a broad historical perspective. Therefore, only at the level of macroevolution, general tendencies, patterns and directions of the evolution of living nature are manifested, which cannot be observed at the microevolutionary level.

Modern concepts of STE indicate that evolutionary changes are random and undirected, since random mutations are the source material for them. Evolution proceeds gradually and divergently through the selection of small random mutations. At the same time, new life forms are formed through major hereditary changes, the right to life of which is determined by natural selection. A slow and gradually ongoing evolutionary process can also have a spasmodic character associated with changes in environmental conditions as a result of the bifurcation processes of the development of our planet.

The synthetic theory of evolution is not some kind of canon, a frozen system of theoretical positions. In its possible range, new areas of research are being formed, fundamental discoveries are appearing and will continue to appear, contributing to further knowledge of the evolutionary processes of living things.

According to modern concepts, an important practical task of STE is to develop optimal ways to control the evolutionary process in the face of constantly increasing anthropogenic pressure on the natural environment. This theory is used in solving problems of the relationship between man and nature, nature and human society.

However, the synthetic theory of evolution has some controversial points and difficulties that give rise to non-Darwinian concepts of evolution. These include, for example, the theory of nomogenesis, the concept of punctualism, and some others.

The theory of nomogenesis was proposed in 1922 by the Russian biologist L. Berg. It is based on the notion that evolution is already a programmed process of realizing internal patterns inherent in living things. A certain internal force of nature is inherent in a living organism, which always acts, regardless of external conditions, purposefully towards the complication of living structures. In support of this, L. Berg pointed to some data on the convergent and parallel evolution of certain groups of plants and animals.

One recent non-Darwinian concept is punctualism. Supporters of this direction believe that the process of evolution proceeds in leaps - by means of rare and fast jumps, which account for only 1% of evolutionary time. The remaining 99% of the time of its existence, the species is in a state of stability. In extreme cases, the leap to a new species may occur in small populations of only ten individuals in one or more generations. This concept is based on the genetic base laid down by molecular genetics and modern biochemistry. Punctualism rejects the genetic-population model of speciation, Charles Darwin's idea of varieties and subspecies as emerging species. Punctualism has focused its attention on the molecular genetics of the individual as the bearer of the properties of the species. The idea of disunity between macro- and microevolution and the independence of the factors controlled by them gives this concept a certain value.

It is likely that in the future a unified theory of life may emerge, combining the synthetic theory of evolution with non-Darwinian concepts of the development of living nature.

Evolutionary picture of the world. Global evolutionism

The idea of world development is the most important idea of world civilization. In its far from perfect forms, it began to penetrate into natural science as early as the 18th century. But already in the nineteenth century can be safely called the age of ideas of evolution. At this time, the concepts of development began to penetrate into geology, biology, sociology and the humanities. In the first half of the XX century. science recognized the evolution of nature, society, man, but the philosophical general principle of development was still absent.

And only by the end of the 20th century, natural science acquired a theoretical and methodological basis for creating a unified model of universal evolution, identifying universal laws of direction and driving forces of the evolution of nature. Such a basis is the theory of self-organization of matter, which represents synergetics. (As mentioned above, synergetics is the science of the organization of matter.) The concept of universal evolutionism, which has reached the global level, linked the origin of the Universe (cosmogenesis), the emergence of the solar system and the planet Earth (geogenesis), the emergence of life (biogenesis) into a single whole , man and human society (anthroposociogenesis). Such a model of the development of nature is also called global evolutionism, since it is precisely this model that covers all existing and mentally represented manifestations of matter in a single process of self-organization of nature.

Global evolutionism should be understood as the concept of the development of the Universe as a natural whole developing in time. At the same time, the entire history of the Universe, starting from the Big Bang and ending with the emergence of mankind, is considered as a single process, where the cosmic, chemical, biological and social types of evolution are successively and genetically closely interconnected. Space, geological and biological chemistry in a single process of evolution of molecular systems reflects their fundamental transitions and the inevitability of transformation into living matter. Consequently, the most important regularity of global evolutionism is the direction of development of the world whole (universe) to increase its structural organization.

In the concept of universal evolutionism, the idea of natural selection plays an important role. Here, the new always arises as a result of the selection of the most effective shaping. Ineffective neoplasms are rejected by the historical process. A qualitatively new level of the organization of matter is "asserted" by history only when it turns out to be capable of absorbing the previous experience of the historical development of matter. This pattern is especially pronounced for the biological form of motion, but it is characteristic of the entire evolution of matter in general.

The principle of global evolutionism is based on understanding the internal logic of the development of the cosmic order of things, the logic of the development of the Universe as a whole. For this understanding, an important role is played by anthropic principle. Its essence is that consideration and knowledge of the laws of the universe and its structure is carried out by a reasonable person. Nature is what it is only because there is a person in it. In other words, the laws of construction of the Universe must be such that it will certainly give rise to an observer someday; if they were different, there would simply be no one to know the Universe. The anthropic principle indicates the internal unity of the patterns of the historical evolution of the Universe and the prerequisites for the emergence and evolution of living matter up to anthroposociogenesis.

The paradigm of universal evolutionism is a further development and continuation of various ideological pictures of the world. As a result, the very idea of global evolutionism has an ideological character. Its leading goal is to establish the direction of the processes of self-organization and development of processes on the scale of the Universe. In our time, the idea of global evolutionism plays a dual role. On the one hand, it represents the world as an integrity, allows you to comprehend the general laws of being in their unity; on the other hand, modern natural science focuses on the identification of certain patterns of evolution of matter at all structural levels of its organization and at all stages of its self-development.