What are the main principles of Darwin's teachings? Evolutionary teaching

Finding out where all life on Earth came from is a complex task that humanity has been struggling with for a long time. There are quite a few hypotheses, from theological (divine) to fantastic (the theory of the creation of the world by alien creatures). Moreover, one of the most popular so far was proposed back in the 19th century by Charles Darwin. Its essence lies in the fact that all species of life on Earth (including humans) appeared in the course of evolution, gradually taking on their current appearance. Some agree with this hypothesis, others do not, however, its significance for all science as a whole is undeniable.

The main provisions are as follows. All living species on the planet were never created by anyone. Organic forms that arose naturally gradually changed in accordance with the conditions surrounding them. This transformation is based on heredity, variability and natural selection. The latter was called by Darwin as As a result of evolution, diversity appeared various types in nature, while they are all maximally adapted to the environment in which they are located.

The main principles of Darwin's theory are described in his book, published in 1859. Here the scientist clearly showed how minor changes in individual organisms lead to the transformation of domestic animals and agricultural plants. As a result, a person chooses those species that are most valuable to him and receives offspring from them. A similar process, the scientist believes, occurs in nature. In his book, Darwin describes it as a long natural process, however, absolutely non-random.

Thus, variability can be of two types: definite and indefinite. The first occurs as a result of exposure to the body external factors, and, as a rule, if they disappear, then these traits no longer appear in the next generation. is inherited regardless of environmental conditions. It is this that is the driving factor in the development of species.

The main provisions of Darwin's theory are based on the fact that the material of evolution is It leads to the fact that an individual develops successful or unsuccessful properties as a result of crossing it with a similar species. Modern biology introduced the name "mutation".

In the struggle for existence, those organisms that are less adaptable to environmental conditions either die or begin to reproduce less. The closer in structure the individuals are in the same territory, the greater the competition between them, as a result of which many of them die. Those who survive are mainly those who acquire various properties (they use a variety of food, means of defense, attack, etc.). As a result of divergence (divergence of characteristics), one species can split into varieties, which can ultimately become an independent unit.

The main provisions of Darwin's theory suggest that living in stable conditions leads to a slowdown in evolution. That is, it is global ones that can cause the emergence of a new species that is significantly different from its supposed ancestors. The scientist provides a lot of evidence to show what exactly determines the adaptability of organisms to changing environmental conditions. For example, in animals this is coloring, in some plants and trees it is the ability to reproduce by dispersing seeds and fruits, etc.

It should be noted that the main provisions of Darwin's theory are quite important for further development science. His works are still being studied; large number research and experimentation.

The construction of the most fundamental evolutionary concept is associated with the name of the brilliant English scientist Charles Darwin (1809–1882). What he accomplished in 1831–1836 was of great importance for the development of Charles Darwin’s evolutionary and atheistic views. circumnavigation of the world on the Beagle. He explored geological structure, flora and fauna of many countries, sent a huge number of collections from England. Having compared the found remains of plants and animals with modern ones, Charles Darwin made an assumption about the historical, evolutionary relationship. On the Galapagos Islands, he found species of lizards, turtles, and birds that were not found anywhere else. The Galapagos Islands are islands of volcanic origin, so Charles Darwin suggested that these animals came to them from the mainland and gradually changed. In Australia, he became interested in marsupials and oviparous animals, which became extinct in other parts globe. So gradually the scientist’s conviction in . After returning from his trip, Darwin worked hard for 20 years to create the doctrine of evolution, collected additional facts about the development of new breeds of animals and varieties of plants in agriculture. he considered it as a unique model of natural selection. His works “The Origin of Species by Natural Selection or the Preservation of Favored Breeds in the Struggle for Life”, “Change in Domestic Animals and Cultivated Plants”, “The Origin of Man and Sexual Selection” were published.

The main merit of Charles Darwin is that he revealed the mechanisms of formation and formation of species, that is, he explained the mechanism of evolution. He made his conclusions on the basis of a large amount of data accumulated by this time in the field of natural science, animal husbandry and crop production. The first possible conclusion drawn by Darwin was the conclusion that it exists in nature. This conclusion was made on the basis that from the emerging huge number individuals, only a few survive to adulthood, therefore, according to Darwin, the rest die in the struggle for life. The second conclusion was the conclusion that for organisms of character there is universal variability in characteristics and properties (even in the offspring of one pair of parents there are no identical individuals). Under fairly stable conditions, these small differences may not matter. However, with sudden changes in living conditions, one or more distinctive features may be decisive for survival. Having compared the facts of the struggle for the existence of the universal variability of organisms, Darwin makes a generalized conclusion about the existence of “natural selection” in nature (the selective survival of some individuals and the death of other individuals). The material for natural selection is supplied by the variability of organisms (mutational and combinative). The result of natural selection is the formation of a large number of adaptations to specific conditions of existence, which we consider from a taxometric point of view - we combine similar organisms into species, genera, and families.

The main provisions of the evolutionary teachings of Charles Darwin boil down to the following:

The diversity of animal and plant species is the result of historical development organic world.
Main driving forces evolution - the struggle for existence and natural selection. The material for natural selection is provided by hereditary variability. The stability of the species is ensured by heredity.
The organic world mainly followed the path of complicating the organization of living beings.
is the result of natural selection.
Both favorable and unfavorable changes can be inherited.
Manifold modern breeds domestic animals and varieties of agricultural plants is the result of action.
associated with the historical development of the ancients great apes.
Charles Darwin's teaching can be considered as a revolution in the field of natural science. Meaning evolutionary theory is as follows:

The patterns of transformation of one organic form into another have been revealed.
The reasons for the expediency of organic forms are explained.
The law of natural selection was discovered.
The essence of artificial selection has been clarified.
The driving forces of evolution have been identified.

In his seminal work Charles Darwin's "Origin of Species" did not deal with the problems of heredity; the term “heredity” is used there about a dozen times. But in the book “Changes in Domestic Animals and Cultivated Plants,” in the final chapter (27th), Darwin outlined his “temporary hypothesis of pangenesis” - the hypothesis of fused inheritance. According to this hypothesis:

• Each cell of a multicellular organism is capable of producing specific new elementary “buds” or “gemmules” corresponding to its morphological structure and functional state.
• All changes that have occurred in somatic cells as a result of exposure to factors external environment, lead to corresponding changes in gemmules.
• The gemmules are carried away by the blood and ultimately enter the germ cells, causing adequate changes in them. In this way, all information about all changes in the body that arose during the process individual development under the influence of various factors, it ends up in germ cells.
• During sexual reproduction, the hereditary material of both parents is mixed, so the offspring is intermediate in characteristics.

Darwin's hypothesis of pangenesis was proposed to substantiate and explain Lamarck's postulate of inheritance of acquired characteristics. Darwin eventually accepted this postulate and included it in the second through sixth editions of the Origin... This was influenced by the comments and objections of critics, as well as the calculations of F. Jenkin. Probably, in connection with this, Darwin redid 75% of the sentences in the text of the 1st edition of “The Origin of Species” up to 5 times.

The pangenesis hypothesis repeated the ideas of Hippocrates (460-377 BC): “I maintain that the seed is separated from the whole body.” Aristotle (384-322 BC) opposed the pangenesis of Hippocrates. "Some say that the seed comes from the whole body. These opinions are supported by evidence of this kind: children resemble their parents not only in innate properties, but also in acquired ones. Namely, if the parents had scars, some of the descendants received a scar sign in the same places." In 1868, three years after Mendel discovered the laws of heredity, Darwin's hypothesis of pangenesis was published. It must be emphasized that Darwin also did experiments with peas and snapdragon. And at the same time, he observed all the basic patterns of inheritance, including a split close to 3: 1. It is interesting that Charles Darwin’s cousin is the famous founder of eugenics, a man who was worshiped by biometricians and fingerprint specialists - Francis Galton during his lifetime. Darwin (in 1875) transfused the blood of black rabbits into white rabbits and found that their offspring remained white.

The hypothesis of pangenesis did not contradict the then ideas of scientists about the inheritance of traits. J. Buffon and P. L. M. Maupertuis had the same views. It should be noted that the pangenesis hypothesis complicated the synthesis of Darwinism with genetics after the rediscovery of Mendel's laws at the beginning of the century.

This video lesson will be useful for those who want to independently consider the topic “Basic provisions of the evolutionary theory of Charles Darwin.” During the lesson you will be able to get acquainted with the personality and biography of the author of evolutionary theory - Charles Darwin. The teacher will talk about the basic principles of evolutionary theory, the first evolutionists and Darwin's trip around the world.

The emergence of Charles Darwin's theory of evolution was the most discussed intellectual event of the 19th century. Translations of new works by the English scientist were published almost simultaneously with publications in the original language. Universities and clubs debated whether “man really came from apes.” It is interesting that Darwin did not make such a statement in any of his works. The scientist believed that humans and monkeys had common ancestors. This assumption was later confirmed by the results of paleontological and genetic studies. Human ancestors separated from apes in the early stages of development.

Charles Darwin was born on February 12, 1809 in the family of a doctor. Over the years of his studies at the universities of Edinburgh and Cambridge, he acquired deep knowledge in the fields of zoology, botany, and geology. A huge role in its formation scientific worldview played by the book of the famous English geologist Charles Lyell. In his works, Lyell said that modern look The earth is formed under the influence of the same conditions that continue to operate to this day. Darwin was also familiar with the work of the first evolutionists, among whom were Lamarck and his grandfather Erasmus Darwin. The decisive turn in Darwin's fate was his participation in a trip around the world on the Beagle as a naturalist. Darwin made this journey from 1832 to 1837 () (see Fig. 1).

Rice. 1

According to Darwin himself, the following facts made the greatest impression on him on this journey:

• The discovery of giant fossil animals that were covered with a shell similar to that of modern armadillos.
• The fact that as you move across the mainland South America closely related animal species replace each other.
• “The fact that closely related species of animals and plants of the various islands of the Galapagos archipelago differ slightly from each other (). It was obvious that these kinds of facts, as well as many others, could only be explained on the basis of the assumption that species were gradually changing, and this problem began to haunt me. So he writes in his book “The Origin of Species by Means of Natural Selection.”

Upon returning from his voyage, Charles Darwin begins to ponder the problem of species variability. He considers various evolutionary theories existing at that time, including Lamarck’s theory, but rejects them one after another, since in none of them Darwin finds an explanation for the facts of the amazing adaptability of living organisms to their environment.

What to the first evolutionists seemed initially given and did not require any explanation became the most important question for Darwin. It collects data on the variability of animal and plant species in nature, as well as under domestication conditions. Many years later, remembering how his theory was born, the great scientist would write the following lines: “I soon realized that the cornerstone of man’s success in creating useful races of animals and plants was selection. However, for some time it remained a mystery to me how selection could be applied to organisms living under natural conditions” ().

Just at this time, the ideas of the scientist Thomas Robert Malthus about the increase in the number of species in geometric progressions were hotly discussed in England. In 1838, Darwin read Malthus's book on population. Since Darwin had been observing living organisms in nature for many years at that time, he was already prepared for the idea of ​​the struggle for existence: “And then I realized that as a result of this struggle, favorable characteristics should be preserved, and unfavorable ones should disappear, and this should lead to the formation of new species."

So, the idea of ​​descent by natural selection first came to Darwin in 1838, and over the next 20 years he worked meticulously on his theory. In 1856, at the insistence of his friend Charles Lyell, Darwin began gradually preparing his works for publication ().

In June 1858, when the work was half completed, Darwin received a letter from another English naturalist, Alfred Russel Wallace, with the manuscript of the latter's article. In this article, Darwin discovered an abbreviated statement of his own theory of natural selection. Two naturalists independently and simultaneously developed identical theories! Darwin sent Wallace's manuscript along with his work to Lyell, who, with the participation of their mutual friend, the English botanist Joseph Hooker, insisted on presenting both works to the Linnean Society in London.

In 1859, Darwin published On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life, which showed variability species of plants and animals, their natural origin from earlier species.

The success of this book exceeds all our wildest expectations. It drew praise from some scientists and uncompromising criticism from others. At the end of the 19th and beginning of the 20th centuries. The ideas of Darwinism were met with hostility by those scientists who considered paleontological evidence to be insufficient and ideas about selection to be undeveloped. However, there were those who put a lot of effort into proving the connection between Darwinism and Mendel's laws of inheritance.

“The Origin of Species” and other works of Darwin, for example “The Descent of Man. Sexual Selection” were translated into many languages ​​and published in huge numbers. Today's students can fully appreciate Charles Darwin's contribution to the modernization of society and science personally by reading his works. The book “Darwin's Origin of Species” is also extremely interesting. Biography,” authored by Janet Brown, a professor at Harvard University, an internationally recognized historian of science and biographer of Charles Darwin.

The essence of the Darwinian concept comes down to a number of logical provisions confirmed by a huge number of facts:

1. Within each species of living organisms there is a wide range of hereditary variability according to morphological and physiological criteria. This variability may be qualitative or quantitative, but it is always present.

2. All living organisms reproduce exponentially.

3. Life resources for any type of living organism are limited, and therefore there must be a struggle for existence and success in reproduction either between organisms of the same species or between organisms different types, or with conditions environment ().

4. In the conditions of the struggle for existence, the most adapted individuals survive and leave offspring, having those deviations that turned out to be useful in the given environmental conditions. This is Darwin's main argument against evolutionary theories. Deviations occur randomly, they are directed in response to changes in the environment, and only a few of these deviations turn out to be useful. The descendants of organisms in which these deviations arose are better adapted to environmental conditions than organisms that do not have them. Darwin called survival and preferential reproduction of the most adapted organisms natural selection ().

5. Natural selection of individual isolated varieties in different conditions environment leads to divergence (divergence) of the characteristics of these varieties and, ultimately, leads to speciation.

Darwin's main achievements as a scientist are that he explained the mechanism of the evolutionary process, revealed its driving forces and created the theory of natural selection. Darwin connected numerous individual phenomena of organic life into a logical whole, thanks to which the kingdom of living nature appeared before people as something striving for constant change and adaptation. Charles Darwin explained the emergence and nature of adaptation solely by the action of natural laws, without the intervention of supernatural forces. Darwin's teaching radically undermined the metaphysical ideas about the constancy of species and their creation by God. Thus, Charles Darwin's theory of evolution completely changed ideas about the development of the organic world and became a colossal scientific discovery. And today, after a century and a half, biological science still follows the direction outlined by the great English naturalist Charles Darwin.

References

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

Homework

1. How did Charles Darwin get on board the Beagle?
2. What ideas about the origin of the diversity of forms of living organisms prevailed in science before the publication of Charles Darwin’s works?
3. Do you agree with Darwinism?
4. Why did R. Wallace, who formulated a similar evolutionary concept, give way to Charles Darwin?

The term "evolution" (from Lat. evolutio- deployment) was introduced into science in the middle of the 18th century. Swiss zoologist Charles Bonnet.

Biological evolution is a progressive, directed historical process of change in living organisms and their communities. The course of evolution is irreversible.

Questions of the origin and diversity of the organic world have always worried humanity. As already noted, the Middle Ages were dominated by creationism - the idea that living organisms are created by God and do not change over time. By the end of the 18th century. discoveries in the fields of chemistry, physics and biology strengthened the idea of ​​the unity of the origin of living organisms and the evolution of the organic world. This became the basis for the creation of a unified evolutionary theory, which was developed by the great English scientist Charles Darwin.

At the turn of the XVIII-XIX centuries. A lot of scientific prerequisites for the creation of evolutionary theory have accumulated. The idea of ​​the variability of the Earth's surface under the influence of climatic factors was substantiated. Chemists have proven that all living organisms consist of the same chemical elements, which are in inanimate nature. Biologists have found that the law of conservation of energy also applies to living organisms. The creation of evolutionary theory was largely influenced by the work of the English economists A. Smith and T. Malthus. A. Smith created the doctrine of free competition in industry. T. Malthus first introduced the expression “struggle for existence.” He explained that humans, like all other organisms, have a natural desire for limitless reproduction. But only the lack of vital resources, the production of which does not keep pace with reproduction, limits the growth of humankind.

At the beginning of the 19th century. French naturalist J.B. Lamarck was the first to propose a consistent doctrine of the development of living nature. Lamarck was the first to point out the connection between organisms and their environment. It was the habitat, in his opinion, that caused the changes in living organisms. The scientist defined the direction of evolution as a gradual transition of living organisms from lower forms to the highest. But at the same time, Lamarck could not be opened real reasons, contributing to this evolutionary transition.

Besides scientific discoveries the formation of the theory of evolution was significantly facilitated by the socio-economic situation - to early XIX V. England became a major industrial and colonial power. The development of navigation, trade, and the development of colonies contributed to the accumulation of knowledge about the flora and fauna different countries. Scaling up industrial production and urban population growth have increased the demand for agricultural raw materials and food. This was an incentive to develop more productive varieties of cultivated plants and highly productive breeds of domestic animals.

The formation of Charles Darwin's evolutionary views

Darwin was born in 1809 into the family of an English doctor. From childhood, Darwin developed a love for nature and field research. Studying at the universities of Edinburgh and Cambridge gave him a deep knowledge of zoology, botany and geology. Darwin studied the evolutionary views of Lamarck and other earlier evolutionists well, but did not share them.

Darwin, studying animals and flora, was very interested in discovering fossil remains of animals. The similarity of these finds with modern forms led him to think about the possible relationship of these organisms. This allowed Darwin to propose continuity between modern and extinct forms of living organisms.

In 1831, Darwin sailed as a naturalist on the sailing ship Beagle to circumnavigation(Fig. 40). For five years, the young scientist studied the geological structure of the continents, flora and fauna of the countries of the world. Darwin drew attention to the peculiarities of the geographical distribution of animals across the continents. For example, in the fauna of South America he discovered forms that were not observed in North America(sloths, anteaters, armadillos). This fact he explained it by the isolation of the fauna caused by the presence of water barriers between the two continents.

During his expedition around the world, Darwin visited the Galapagos Islands, located off the west coast of South America. There the scientist discovered species of songbirds passerine birds- finches, which differed from each other in the shape of their beaks and the type of food. At the same time, the island finches were very similar to the mainland species, which undoubtedly indicated their close relationship.

The beaks of some species of finches were ideal for collecting seeds, while others were adapted only for collecting insects. Moreover, all the finches on the islands were generally quite similar. Darwin suggested that birds of the same species of finches once flew to the islands, and having settled, they adapted to local conditions. The advantage in survival was given to species whose beaks were more suitable for obtaining the food available on the islands. Some finches got the role of hunters for small insects, others received an abundance of fruits and seeds. As a result, several different species of these birds gradually emerged, specializing in some type of food.

As a result, at the end of the expedition, based on extensive factual material, Darwin made important conclusions. Firstly, he confirmed that species are capable of changing and giving rise to new species. Secondly, based on self-study fossil remains and previously known paleontological research data, the scientist proved the similarity in the structure of extinct and modern animals.

Basic principles of Charles Darwin's theory of evolution

After returning to England, Darwin began painstaking work on creating an evolutionary theory. Studying the works of Smith and Malthus, he tried to find similar phenomena in nature. As you know, the ability to reproduce unlimitedly is one of the main properties of living things. For example, many herring fish Every year up to 100 thousand eggs are laid, and cod - up to 6 million. But only a small part of the offspring survives. Darwin laid this discrepancy between the number of organisms born and those reaching sexual maturity as the basis for his doctrine of struggle for existence. He also pointed out that organisms have variability- individual differences in characters between individuals of the same species. Darwin first published the results of his research in 1859 in the book “The Origin of Species by Means of Natural Selection.”

Basic principles of Charles Darwin's theory of evolution:

1. Species of living organisms had a single origin and were progressively transformed and improved in accordance with environmental conditions.
2. The transformation of species occurs on the basis of heredity and variability of living organisms and natural selection constantly occurring in nature.
3. Natural selection in nature is carried out on the basis of the relationships of organisms with each other, and with unfavorable conditions environment. These relationships represent a struggle for existence.
4. The result of natural selection is the emergence of fitness and, on this basis, the diversity of species of living organisms in nature.

Having analyzed the main provisions of evolutionary theory, we can conclude that, from Darwin’s point of view, the smallest evolving unit is elementary unit of evolution is the view. Prerequisites for evolution, creating material for selection in the form of hereditarily fixed differences among individuals, serve heredity and variability organisms. Driving forces of evolution leading to the formation of new species are struggle for existence And natural selection.

In the book “The Origin of Species by Means of Natural Selection,” Charles Darwin proved that the prerequisites for evolution are heredity and variability of organisms. Natural selection and the struggle for existence are the main driving forces of evolution. The result of natural selection is the emergence of fitness and, on its basis, the diversity of species of living organisms in nature.