The concept of evolutionism 1. The concept of "evolution". 2. The main postulates of the concept of the evolution of the organic world. 3. The principles of global evolutionism.

The concept of "evolution" 1. The evolutionary theory is now not considered as a unified description of an unambiguous path of development, which is known by science to the end, rather, evolutionism in modern science is a spectrum of variously grounded concepts. 2. Evolution implies an overall gradual development, orderly and consistent.

The concept of "evolution" By the second half of the 18th century, there were objective prerequisites for the emergence of scientifically grounded evolutionist views: descriptions of many new species as a result of geographical discoveries; the unity of the plan of the structure of many previously known groups of organisms has been established; the emergence of a special biological discipline - paleontology; the emergence of scientifically based theories of the origin of the Earth and the solar system

Evolution. At the turn of the 18th and 19th centuries, revealing the laws of the historical development of the flora and fauna became a priority task.

The main postulates of the concept of the evolution of the organic world. French biologist Jean-Baptiste Lamarck (1744 - 1829) put forward a hypothesis about the mechanism of evolution. He published his views, which are now considered the essence of Lamarckism, in the work "Philosophy of Zoology" in 1809. The implementation of the principle of gradation, according to Lamarck, becomes possible due to the presence in organisms of an internal desire for improvement.

The main postulates of the concept of the evolution of the organic world. The main generalization of Lamarck's views are two provisions that went down in the history of science under the name "Lamarck's laws". 1. In all animals that have not reached the limit of their development, organs and systems of organs that have been subjected to prolonged intensified exercise gradually increase in size and become more complex, while those that are not exercised become simpler and disappear. 2. Signs and properties acquired as a result of long-term and stable exposure to the external environment are inherited and preserved in the offspring, provided they are present in both parental organisms.

The main postulates of the concept of the evolution of the organic world. Lamarck's concept represented the first complete system of evolutionary views and at the same time the first attempt to substantiate these views. Lamarck as a whole correctly characterized evolution as a progressive process moving in the direction of increasing the complexity of the structure of organisms. For his time, Lamarck's views on the adaptive nature of the evolutionary process were advanced. Lamarck's concept contained a number of erroneous provisions: 1. explanation of the evolutionary process as a result of an internal striving for improvement. 2. the assumption of the possibility of the appearance of inherited adaptive traits in response to the influence of the environment. 3. denial of the reality of the species.

The main postulates of the concept of the evolution of the organic world. Charles Darwin's theory of evolution (born Charles Robert Darwin;) is considered one of the main scientific revolutions, since in addition to its purely scientific significance, it led to a revision of a wide range of worldview, ethical, and social problems.

The main postulates of the concept of the evolution of the organic world. Charles Darwin's theory of evolution has several scientific components. 1. The concept of evolution as reality, which means the definition of life as a dynamic structure of the natural world, and not a static system. 2. As a result of excess fertility between organisms in nature, there is competition for the environment and food - "the struggle for existence." It is customary to distinguish between three of its forms: the fight against factors of nonbiological (abiotic) origin, interspecific and intraspecific struggle.

The main postulates of the concept of the evolution of the organic world. Due to the presence of variability, different individuals in the process of struggle for existence find themselves in an unequal position. Individual changes that facilitate survival provide their carriers with an advantage, as a result of which individuals who are more adapted to these conditions often survive and give birth to offspring, and the weaker are more likely to die or are eliminated from crossing. This phenomenon Darwin called natural selection.

The main postulates of the concept of the evolution of the organic world. The adaptive nature of evolution is achieved by selecting from a variety of random changes such that facilitate survival in the given, specific environmental conditions. The fitness of organisms is, as a rule, relative.

The main postulates of the concept of the evolution of the organic world. Darwin deduced that species originated by natural selection based on five basic postulates: 1. All species have the biological potential to increase the number of individuals to large populations. 2.Populations in nature demonstrate the relative constancy of the number of individuals over time. 3. The resources required for the existence of species are limited, so the number of individuals in populations is approximately constant over time. Conclusion 1. Between representatives of the same species there is a struggle for the resources necessary for survival and reproduction. Only a small proportion of individuals survive and produce offspring.

The main postulates of the concept of the evolution of the organic world. 4. There are no two individuals of the same species, which would have the same properties. Representatives of one species show great variability. 5. Basically, the variability is determined genetically, therefore it is inherited. Conclusion 2. Competition between representatives of the same species depends on the unique hereditary properties of individuals that provide advantages in the struggle for resources for survival and reproduction. This unequal ability to survive is natural selection. Conclusion 3. The accumulation of more favorable properties as a result of natural selection leads to a constant change in species. This is how evolution happens.

Evidence for an Evolutionary Concept Evidence for current understanding of evolution comes from a variety of sources. Some of the events cited as evidence for evolutionary theory can be replicated in the laboratory, however, this does not mean that they actually took place in the past, they simply indicate the possibility of such events.

Evidence for an evolutionary concept. Taxonomy Natural classification can be phylogenetic or phenotypic. Phylogenetic classification is more often used, since it reflects evolutionary relationships, which are based on the origin of organisms and their inheritance of certain traits. Similarities and differences between organisms can be explained as a result of the progressive adaptation of organisms within each taxonomic group to certain environmental conditions over a certain period of time.

Evidence for an evolutionary concept. The following basic hierarchical units are used in taxonomy: Kingdom; Type (department in plants); Class; Detachment (order in plants); Family; Genus; View. Each taxon can contain several taxonomic units of a lower rank. However, at the same time, a taxon can belong to only one taxon located immediately above it. There may be several taxa at each hierarchical level, but they all differ from each other.

Evidence for an evolutionary concept. Comparative Anatomy The presence of homologous and rudimentary organs is considered as evidence of the origin of animals from a common ancestor. The blinking membrane is a "rudiment" of a person.

The concept of catastrophism The hypotheses of catastrophists can be divided into two main groups. 1. Terrestrial catastrophism: catastrophes are associated with geological processes (revival of volcanism, leading to global cooling and the release of large amounts of toxic substances into the atmosphere, mountain-building processes associated with climate change).
concept of catastrophism 2. Cosmic catastrophism: catastrophes are of cosmic origin: catastrophic increase in radiation caused by a supernova explosion; fluctuations in solar activity; b ombardment of the Earth by comets and giant asteroids, coupled with fluctuations in the position of the solar system relative to the plane of the galaxy; the passage of a large celestial body through the cometary cloud surrounding the solar system.

The concept of catastrophism In 1980, the American physicist, Nobel laureate L. Alvarez and his son geologist U. Alvarez suggested that the iridium anomaly was a consequence of the impact of a large asteroid on the Earth, the substance of which was scattered over the entire earth's surface. That led to a complete short-term suspension of photosynthesis and mass death of green plants, and after green plants, the death of herbivorous animals, and then predators.

The concept of catastrophism None of the catastrophic models explain the meaning of the processes taking place on Earth in critical epochs, but rather raise new questions. Psychological factors (the novelty of the idea of ​​asteroids) play an important role in the dissemination of alternative, anti-Darwinian concepts of evolution.

The ratio of micro- and macroevolution. Microevolution is a set of evolutionary processes occurring in populations of a species and leading to a change in the gene pool of these populations and the formation of new species. Macroevolution - evolutionary transformations leading to the formation of taxa of a higher rank than the species.

The evolution of the organic world.

Definition of evolution.

Evolution theories.

Biological species, its population structure.

The effect of elementary factors on the population.

Biological evolution is based on the processes of self-reproduction of macromolecules and organisms.

Biological evolution is an irreversible and directed historical development of living nature.

Biological evolution is accompanied by:

Changes in the genetic makeup of the population;

Formation of adaptations;

Formation and extinction of species;

The transformation of ecosystems and the biosphere as a whole.

There is a correspondence between organisms and the external environment. Everyone can exist and reproduce their own kind only in an environment corresponding to him.

1809 Jean Baptiste Lamarck focused on the progressive development of organisms.

Evolution principles (according to Lamarck)

The existence in organisms of an internal desire for self-improvement.

The ability of organisms to adapt to circumstances, i.e. external environment.

Frequent acts of spontaneous generation.

The inheritance of acquired characteristics and traits.

Important merit - 2nd position. Lamarck was unable to prove his theory, in addition, there was no empirical evidence to support his point of view. Later, neo-Lamarckism arose.

K. Rouvier developed the concept of the emergence of the organic world from the inorganic, of the gradual natural change of organisms, of the formation of a variety of living beings under the influence of changes in external conditions, of heredity and variability as the main properties of living organisms.

Beketov in 1854 he conducted a study of changes in plants.

1858 - Darwin made a preliminary report on the theory in the Linnaean society. A. Wallres drew the same conclusions and wrote a letter to Charles Darwin, t. to. by the time Wallres wrote the manuscript, Darwin had already published some of the works. Darwin was not the first to suggest a theory of universal evolution, but he proved that evolution exists, and in addition, there are driving forces of evolution in nature.

On November 24, 1859, Darwin's Origin of Species by Natural Selection was published in full.

Postulates of Darwin's theory.

The world around us is not static, but constantly evolving. Species are constantly changing, some species emerge, others die out.

The evolutionary process takes place gradually and continuously. The evolutionary process is not a collection of individual leaps or sudden changes.

Similar organisms are descended from a common ancestor and are related by ties of kinship.

Natural selection theory.

Until the 1930s, when the theory of synthetic evolution appeared, there were many discrepancies. All theories can be divided into 4 groups:

Monistic;

Synthetic;

Discontinuous equilibrium theory;

The theory of neutral mutations.

Monistic theories attribute evolutionary change to a single factor.

Ectogenetic - changes are caused directly by the environment.

Endogenetic - changes are controlled by internal forces, true Lamarckism.

Random events ("accidents") - spontaneous mutations, recombinations.

Natural selection.

Synthetic theories explain evolutionary change by the action of many factors.

Most of the theories are Lamarckian;

Charles Darwin's late views;

The early stage of "modern synthesis";

The modern stage.

1926 - Chetverikov in "Experimental Biology" published an article "On some aspects of the evolutionary process from the point of view of modern genetics." Tied up some of Darwin's facts.

1935 - II Vorontsov formulated the main provisions of the synthetic theory of evolution (11 postulates).

Synthetic theory of evolution.

The smallest unit of evolution is the local population.

The main factor in evolution is natural selection.

Evolution is divergent in nature (convergent, parallel).

Evolution has a gradual step-by-step nature (sometimes abrupt).

Allele exchange and gene flow occurs only within the same species.

Macroevolution follows the path of microevolution.

A species consists of many subordinate units.

The concept of a species is unacceptable to forms that do not have sexual reproduction.

Evolution is carried out on the basis of variability (so-called tychogenesis).

The taxon has monophilic capabilities (descended from a single ancestor).

Evolution is unpredictable.

It became clear that the elementary unit of evolution is not one organism, but a population. It has been established that the cause of evolution is not a separate factor, but the interaction between many factors that are realized as a result of natural selection.

The synthetic theory of evolution is accepted by most scientists. All the provisions at the level of microevolution have been proven, at the level of macroevolution they have not yet been sufficiently confirmed, therefore new evolutionary theories are being created.

In addition to the synthetic theory, the concept of discontinuous equilibrium is interesting. In evolution, periods of stability of species alternate with short periods of rapid speciation. The emergence of sudden mutations is associated with regulatory genes. However, no regulatory genes have been found in plants.

The theory of neutral mutations. Authors - King, Kimura - 1970 Appeared after the discovery of patterns in molecular biology. The main factor at the molecular level is not natural selection, but chances that lead to the fixation of neutral or near-neutral mutations. Changes occur in the sequence of DNA triplets, and proteins change accordingly. DNA changes are caused by random gene drift. The theory does not deny the role of natural selection, but believes that only a small fraction of DNA changes are adaptive. Most changes in phylogenetic influence do not have, they are not selective, neutral and have no role in evolution. The theory has evidence: leucine is collated by 6 triplets, which are preferred in different animal species. Changing the triplet in this case does not change anything, however, different triplets in different animals perform the function of a "key".

Zavatsky - "General characteristics of a biological species."

number;

type of organization / specific set of chromosomes;

reproduction (in the process of reproduction, the species retains itself);

discreteness (a species exists and evolves as a separate entity);

ecological certainty. The species is adapted to certain conditions, where it is competitive;

geographic certainty / range of the species;

variety of forms - internal structure of the species - population;

historicity. A species is a system capable of evolutionary development;

stability;

integrity. A species is a tribal community united by certain adaptations and intraspecific relationships.

The question of what a biological species is has not been resolved. Basic concepts:

Philosophical and logical concept;

Biological concept;

Morphological concept.

According to the philosophical and logical concept, a species is a category of thinking. Common properties are common to all representatives.

Morphological criterion is the application of a philosophical and logical concept to living organisms. Species are determined strictly by the presence of certain characters in a population (Linnaeus, most naturalists and taxonomists of the 18th - 19th centuries).

The biological concept is based on the fact that all species are made up of populations. Individuals are potentially capable of interbreeding with each other, species exist in reality, individuals have a common genetic program that has developed in the process of evolution. It is a reproductive community, an ecological unit, a genetic unit. The species has a genetic isolation and reproductive isolation. The essence of the species is reflected in the genetic structure. The species is characterized by genetic diversity.

View- a group of morphologically similar organisms that have a common origin and are potentially capable of interbreeding with each other in natural conditions.

Individuals do not always live with each other in a close relationship (immediate neighborhood); they live in populations.

Population traits.

The population is a freely interbreeding group.

The panmix group is a reproductive unit.

A population is an ecological unit. Individuals are genetically similar in ecological requirements.

Population- a group of individuals of the same species, inhabiting a certain territory for a long time, freely interbreeding with each other in natural conditions and giving fertile offspring.

The size of the population is unstable. Real populations are different in shape and number of individuals.

Population structure.

Spatial configuration;

Breeding system;

Migration speed.

Depending on the spatial configuration, there are:

Large continuous populations (tens and hundreds of kilometers).

Small colonial populations (corresponding to the island type).

The breeding system has large ranges of values.

Autogamous populations - reproduce by self-fertilization.

Allogamous populations - reproduce by cross fertilization.

In autogamous ones, homozygous organisms prevail, the proportion of heterozygotes is small.

Allogamous populations are characteristic of all animals and some plants. The composition of the alleles is determined by mutations and, for the most part, by gene recombinations. Because offspring occurs due to crossing, the proportion of heterozygotes is large. The numbers of genotypes reach values ​​characteristic of the Hardy - Weinberg law. Until the factors of evolution act, the ratios remain. Microevolutionary factors cause chromosomal aberrations, mutations and other changes - this is the main factor of evolution.

Evolution factors.

Mutational process.

Gene flow.

Gene drift.

Natural selection.

The mutation process and gene flow create variability. Genetic drift and natural selection sort her, work on her, and shape her destiny.

Mutational process. Each mutant allele appears very rarely for the first time. If it is neutral, elimination occurs. If useful, it accumulates in the population.

Gene flow. A new gene can manifest itself only as a result of mutation, but a population can receive it when the carrier of this gene immigrates from another population. Gene flow is the transfer of genes from one population to another. Gene flow can be considered a lagging effect of the evolutionary process. The carriers of gene flow are different.

Natural selection is composed of different processes:

Driving (directed, progressive) selection - established by Charles Darwin.

Stabilizing.

Disruptive (tearing) Mauer.

Driving selection- directed selection, in which the population changes with the habitat. It occurs when the population gradually changes with the environment.

Stabilizing selection- selection that occurs when the environment does not change, the population is well adapted, extreme forms are eliminated, and the number grows.

Disruptive selection- selection, in which the elimination of medium forms occurs, and the extreme variants are preserved. Genetic polymorphism. The more polymorphic the population is, the easier the process of speciation is.

Gene drift. The Hardy-Weinberg law is only possible in ideal populations. In small populations, there are deviations from this distribution. Random changes in genotypes and allele frequencies during the transition from one generation to another is gene drift, which is characteristic of a small population.

the population system consists of a number of isolated colonies;

the population is large, then shrinks and recovers at the expense of surviving individuals;

a large population gives rise to several colonies. Individuals - ancestors form colonies.

1. Theory evolution organic the world

   Abstract >> Biology

   Formation of an idea evolution organic the world taxonomy played a significant role - biological science ... in the sex cells of material structures, predetermining the development of the embryo and ... population-genetic research that has been implemented his ...

2. Biological map the world

   Abstract >> Biology

   ... evolution organic the world taxonomy played a significant role - biological... material structures, ... species to the idea evolution, historical development species assumed, first, consideration of the educational process species v his ... population waves ...

3. Theory evolution (4)

   Cheat Sheet >> Biology

   Regularity evolution organic the world... Theory... view and opportunities his further evolution... With the emergence of man as a social being biological factors

Paleontological data, supported and supplemented by morphological and embryological materials, are historical documents, according to which scientists reconstruct the specific course of development of the organic world on our planet.

According to modern data, the Earth as a planet emerged about 7 billion years ago. The entire time of our planet's existence is divided into eras. Eras, in turn, are subdivided into periods. Their sequence and approximate duration are shown in Table 1.

Pre-geological era- the era of the formation of the planet itself. It began 6-7 billion years ago and lasted about 3 billion years; there was still no life on Earth at that time.

Archean era- the era when life arose on Earth in the waters of the primary seas. Despite the length of the Archean era, by the end of its life was still represented by rather primitive forms: unicellular (, flagellate, blue-green) and only a small number of multicellular (algae and primitive coelenterates). In the Archean era, the branches of the animal and plant world were quite clearly divided, having a common ancestor - unicellular flagellates. This division arose on the basis of nutrition; primitive animals continued to be heterotrophic organisms, and algae acquired the ability to photosynthesize and thus turned into autotrophic organisms. Certain bacteria, which acquired the ability to chemosynthesis, also became autotrophs. There is reason to believe that primitive forms of sexual reproduction also arose in this era.

Proterozoic era- one of the longest. At this time, new types of algae appear, which later will become the original ones for all other groups of the plant world. Mass algae in the Proterozoic era played a decisive role in the evolution of the animal world: a large amount of free oxygen accumulated in the water and in the atmosphere due to photosynthesis. The animal world has come a long way in the Proterozoic era: types of lower worms and mollusks have emerged. By the end of the era, primitive arthropods and skullless chordates (close to the modern lancelet) appeared. But life still exists only in water. However, some algae and bacteria probably penetrated into wet land areas, starting the first soil-forming processes there.

Palaeozoic- the era of major events in the history of the organic world. The central one is the exit of plants and animals to land.

The pioneers of sushi among the plant were some algae, bacteria and lower ones. The first soil-forming processes are associated with their activity. The most ancient land plants are known from the Silurian period - psilophytes... Their descendants in the Devonian period were the ancient ferns, which flourished in the Carboniferous period. In the same period, the first gymnosperms appeared, which in the last - Permian period acquired a dominant position.

stegocephalic.

Reaching its heyday in Carboniferous period Paleozoic era.

So, during Paleozoic era

Mesozoic era

Triassic the first mammals, and in Jurassic

Cenozoic era

During Paleogene

By the end neogene anthropogen

Psilophytes. Their descendants in the Devonian period were the ancient ferns, which flourished in the Carboniferous period. In the same period, the first gymnosperms appeared, which in the last - Permian period acquired a dominant position.

The development of land by animals went in two ways: the first invertebrates to land, apparently, were scorpions, millipedes and wingless insects; among vertebrates, amphibians became pioneers of land. Invertebrates began to colonize land in the Silurian period. In the Carboniferous period, real winged insects appeared (similar to our dragonflies and cicadas), sometimes reaching very large sizes. Marine animals (cephalopods, shark fishes) have also reached a high level of organization.

Terrestrial vertebrates originated from a very peculiar group of cross-finned fish of the Devonian period. And although the cross-finned fish continued to be aquatic animals, the prerequisites for a terrestrial lifestyle arose in their organization. Powerful pectoral and pelvic fins allowed them to move from one body of water to another during a drought; The swim bladder, abundantly supplied with blood vessels, performed the function of respiration at the moments of such transitions. Gradually, in the course of natural selection, one of the branches of the cross-finned fish gave rise to primitive amphibians - stegocephalic.

Reaching its heyday in Carboniferous period, amphibians then gave way to reptiles on land. The intensive development of ancient reptiles began in the Permian period Paleozoic era.

So, during Paleozoic era plants have gone from algae to gymnosperms, vertebrates - from primitive chordates of the lancelet type to reptiles on land and to shark fish in water, and one of the branches of invertebrates (we did not consider others) - from primitive marine arthropods to real flying insects.

Mesozoic era was twice as short as the Paleozoic, but during this time there have been significant changes in the organic world.

Among gymnosperms, the most progressive branch, conifers, arose (Triassic period). In the Jurassic period, the first angiosperms appeared, which by the end of the era had already taken a dominant position and were represented by a large variety of species.

The progressive development of vertebrates led to the emergence of Triassic the first mammals, and in Jurassic- the first birds; However, reptiles still dominate. Therefore, the Mesozoic era as a whole is often called the era of reptiles. But by the end of the Cretaceous period, a huge number of reptile species are rapidly dying out. Science has not yet found a sufficiently complete explanation for this amazing fact. Undoubtedly, the cooling of the climate played a role in it; an extremely important circumstance was the rapid spread of the most progressive classes of vertebrates - birds and mammals in the air and teleost fishes in the aquatic environment. And yet, the speed with which its ancient masters disappeared from the face of the earth is surprising and encourages scientists to search for the causes of this mysterious phenomenon.

Cenozoic era- the shortest. But its significance for the present and future of the entire organic world is enormous. The reason is that it was in the Cenozoic era that man appeared on Earth. And with it, not only a new form of motion of matter arose on Earth, which will be discussed in the next chapter, but also the nature and direction of the evolution of the organic world as a whole changed radically.

The Cenozoic era brought the final victory among vertebrates to mammals, birds and bony fishes. The reserves of nutrients in the seeds, fruits and organs of vegetative propagation of angiosperms provided rich food for the first two classes of vertebrates. The evolutionary development of these higher representatives of the plant and animal world proceeded in close interaction. In turn, the development of flowering plants is inextricably linked with further progress in the world of invertebrates and, above all, insects. Thus, in a complex and multifaceted interaction, the gradual formation of modern flora and fauna took place.

During Paleogene and the Neogene, the outlines of continents and deep seas took mainly their modern form. The warm climate of these periods contributed to the exuberant growth and intense morphogenesis of angiosperms, which firmly occupied a dominant position in the flora of all continents. Tropical and subtropical vegetation spread far to the north in comparison with modern ones.

By the end neogene a cold snap sets in, ending with the beginning of the first glaciation. The range of subtropical and tropical plants has sharply decreased. The distribution of vegetation across the globe in the interglacial periods of anthropogenic time gradually acquired a modern character. And the very name of the last period of the Cenozoic era - anthropogen- testifies to the most important event of this period - the appearance of a person.

Until the end of the 17th century. most Europeans believed that everything in nature remains unchanged from the day of creation, that all types of plants and animals are still as God created them. However, in the XVIII century. new scientific evidence has cast doubt on this. Humans began to find evidence that plant and animal species change over long periods of time. This process is called evolution.

The first theories of evolution

Jean-Baptiste de Monet (1744-1829), Chevalier de Lamarck, was born in France. He was the eleventh child in an impoverished aristocratic family. Lamarck lived a difficult life, died a blind beggar, his works were forgotten. At the age of 16, he joined the army, but soon retired due to poor health. Need forced him to work in a bank, instead of doing what he loved - medicine.

Royal Botanist

In his spare time Lamarck studied plants and acquired such a vast knowledge in this that in 1781 he was appointed chief botanist of the French king. Ten years later, after, Lamarck was elected professor of zoology at the Museum of Natural History in Paris. Here he gave lectures and arranged exhibitions. Noticing the differences between fossils and modern animal species, Lamarck came to the conclusion that the species and characteristics of animals and plants are not unchanged, but, on the contrary, change from generation to generation. This conclusion was prompted to him not only by fossils, but also by geological evidence of changes in the landscape over many millions of years.

Lamarck concluded that throughout life, the characteristics of an animal can change depending on external conditions. He proved that these changes are inherited. So, the neck of a giraffe could lengthen during his life due to the fact that he had to reach for the leaves of trees, and this change was passed on to his offspring. Nowadays, this theory is recognized as erroneous, although it was used in the theory of evolution that appeared 50 years later by Darwin and Wallace.

Expedition to South America

Charles Darwin (1809-1882) was born in Shrewsbury, England. He was the son of a doctor. After graduating from school, Darwin went to study medicine at the University of Edinburgh, but soon became disillusioned with this subject and, at the insistence of his father, left for Cambridge University to prepare for the priesthood. And although the preparation was successful, Darwin again became disillusioned with the career ahead of him. At the same time, he became interested in botany and entomology (the science of insects). In 1831, professor of botany John Henslow noticed Darwin's abilities and offered him a place as a naturalist on an expedition to South America. Before sailing, Darwin read the works of the geologist Charles Lyell (see article ""). They amazed the young scientist and influenced his own views.

Darwin's discoveries

The expedition sailed on the Beagle and lasted 5 years. During this time, the researchers visited Brazil, Argentina, Chile, Peru and the Galapagos Islands - ten rocky islands off the coast of Ecuador in the Pacific Ocean, each of which has its own fauna. On this expedition, Darwin collected a huge collection of rock fossils, made herbariums and a collection of stuffed animals. He kept a detailed diary of the expedition and subsequently used many of the materials made in the Galapagos Islands in presenting his theory of evolution.

In October 1836 the Beagle returned to England. For the next 20 years, Darwin devoted himself to processing the collected materials. In 1858 he received a manuscript from Alfred Wallace (1823-1913) with ideas very close to him. And although both naturalists were co-authors, Darwin's role in advancing a new theory is much more significant. In 1859, Darwin published the book The Origin of Species by Natural Selection, in which he outlined the theory of evolution. The book was a huge success and made a lot of noise, as it contradicted traditional ideas about the origin of life on Earth. One of the boldest thoughts was the assertion that evolution took many millions of years. This contradicted the teaching of the Bible that the world was created in 6 days and has not changed since then. Today, most scientists use a modernized version of Darwin's theory to explain changes in living organisms. Some, however, reject his theory for religious reasons.

Natural selection

Darwin discovered that organisms compete with each other for food and habitat. He noticed that even within the same species, there are individuals with special characteristics that increase their chances of survival. The offspring of such individuals inherits these traits, and they gradually become common. Individuals that do not have these signs die out. So, after many generations, the whole species acquires useful characteristics. This process is called natural selection. Let's see, for example, how the moth adapted to the changes in the habitat. At first, all moths were silver in color and were invisible on the branches of trees. But then the trees darkened from the smoke - and the moths became more noticeable, they were more actively eaten by birds. The darker colored moths survived. This dark coloration passed on to their offspring and subsequently spread to the entire species.

The role of Charles Darwin's works in the creation of a scientific evolutionary theory

By the middle of the XIX century. objective conditions arose for the creation of a scientific evolutionary theory. They boil down to the following.

1. By this time, biology had accumulated a lot of factual material proving the ability of organisms to change, and the first evolutionary theory was created.

2. All the most important geographical discoveries were made, as a result of which the most important representatives of the organic world were described in more or less detail; discovered a wide variety of species of animals and plants, identified some intermediate forms of organisms.

3. The rapid development of capitalism required the study of the sources of raw materials (including biological) and sales markets, which intensified the development of biological research.

4. Great successes have been achieved in the selection of plants and animals, which contributed to the identification of the causes of variability and the consolidation of the emerging traits in organisms.

5. Intensive development of minerals made it possible to discover cemeteries of prehistoric animals, prints of ancient plants and animals, which confirmed evolutionary ideas.

Charles Darwin (1809-1882) became the creator of the foundations of scientific evolutionary theory. Its main provisions were published in 1859 in the book The Origin of Species by Natural Selection, or the Conservation of Favorable Races in the Struggle for Life. C. Darwin continued to work on the development of evolutionary theory and published the books "Change in domestic animals and cultivated plants" (1868) and "The origin of man and sexual selection" (1871). The evolutionary theory is constantly developing, supplemented, but its foundations were laid out in the above books.

The creation of Darwin's theory was facilitated by the situation in biology at the time of the beginning of the scientist's scientific activity, the fact that he lived in the most developed (at that time) capitalist country - England, the ability to travel (Charles Darwin made a round-the-world trip on the Beagle ship) as well as the personal qualities of the scientist.

When developing a scientific evolutionary theory, Charles Darwin created his own definition of "species", put forward new principles for the systematization of the organic world, consisting in finding related (genetic) relationships that have arisen due to the same origin of the entire organic world; gave a definition of evolution as the ability of species to slow, gradual development in the course of their historical existence. He correctly revealed the cause of evolution, consisting in the manifestation of hereditary variability, and also correctly revealed the factors (driving forces) of evolution, including natural selection and the struggle for existence, through which natural selection is realized.

The theory of the evolution of the organic world, developed in the works of Charles Darwin, was the foundation for the creation of a modern synthetic evolutionary theory.

The synthetic theory of the evolution of the organic world is a set of scientifically grounded provisions and principles that explain the emergence of the modern organic world of the Earth. In developing this theory, the results of research in the field of genetics, breeding, molecular biology and other biological sciences, obtained in the second half of the 19th and throughout the 20th century, were used.

Karl Linnaeus and the role of his work in the formation of evolutionary theory

Man has always been interested in where such a wonderful world of animals and plants came from, whether it was always the same as it is now, whether organisms that exist in nature change. With the eyes of one generation, it is difficult, and sometimes impossible, to detect significant changes in the world around us, therefore, a person initially formed an idea of ​​the immutability of the surrounding world, especially the world of animals (fauna) and plants (flora).

The concepts of the immutability of the organic world are called metaphysical, and people (including scientists) who share these views are called metaphysicians.

The most ardent metaphysicians, who believe that all living things were created by God and do not change from the day of creation, are called creationists, and the pseudo-teaching about the divine creation of living things and its immutability is called creationism. This is an extremely reactionary doctrine, it inhibits the development of science, interferes with the normal human activity both in the development of civilization and in ordinary life.

Creationism was widespread in the Middle Ages, but even today believers and church leaders adhere to this doctrine, however, and now the church recognizes the mutability of the living and believes that only the soul was created by God.

With the accumulation of knowledge about nature, the systematization of knowledge, it was revealed that the world is changing, and this later led to the creation and development of an evolutionary theory.

An outstanding scientist-biologist who was a metaphysicist and creationist, but his works prepared the possibility of developing an evolutionary theory, was the Swedish natural scientist Karl Linnaeus (1707-1778).

K. Linnaeus created the most perfect artificial system of the organic world. It was artificial because Linnaeus based it on features that often did not reflect the relationship between organisms (which at that time was impossible due to the incompleteness of knowledge about organisms). So, he classified lilac and sweet spike (plants of completely different classes and families) in one group because both of these plants have two stamens (sweet spike belongs to the class of monocotyledons, the family of cereals, and lilacs to the class of dicotyledons, the olive family) ...

The system proposed by K. Linney was practical and convenient. It used the binary nomenclature that Linnaeus introduced and which is still used today because of its rationality. In this system, class was the highest taxon. Plants were divided into 24 classes, and animals - into six. The scientific feat of K. Linnaeus was the inclusion of man in the kingdom of Animals, which during the undivided domination of religion was far from safe for the scientist. The significance of the Linney system for the further development of biology is as follows:

1) it created the basis for scientific systematization, since it clearly showed that there is a relationship and kinship between organizations;

2) this system posed the task of elucidating the reasons for the similarities between organisms, which was an incentive for studying the deep features of similarities and explaining the reasons for such similarities.

Towards the end of his life, K. Linney abandoned the idea of ​​immutability of species, since the system of the organic world proposed by him did not fit into the framework of metaphysical and creation ideas.

General characteristics of the evolutionary theory developed by J. B. Lamarck

At the end of the 18th - beginning of the 19th century. the idea of ​​the changeability of the organic world is increasingly conquering the minds of scientists. The first evolutionary theories appear.

Evolution is a gradual long-term development of the organic world, accompanied by its change and the emergence of new forms of organisms.

The first, more or less grounded evolutionary theory was created by the French naturalist Jean Baptiste Lamarck (1744-1829). He was a prominent representative of transformism. J. Buffon (France), Erasmus Darwin - the grandfather of Charles Darwin (England), I. V. Goethe (Germany), C. F. Rouillet (Russia) were also transformists.

Transformism is the doctrine of the variability of species of various organisms, including animals, plants and humans.

JB Lamarck outlined the foundations of his theory of evolution in the book "Philosophy of Zoology". The essence of this theory is that organisms change in the course of historical existence. Changes in plants occur under the direct influence of environmental conditions; these conditions affect animals indirectly.

The reason for the emergence of new forms of organisms (especially animals) is the internal striving of the organism for perfection, and the changes that have appeared are consolidated through exercise or non-exercise of organs. The resulting changes are inherited by the body under the successive impact of the conditions that caused these changes, if these conditions are valid for several generations.

The central position of Lamarck's evolutionary theory is the idea of ​​the types of organisms, their gradation and the desire of the species to move from a lower level (gradation) to a higher one (hence the desire for perfection).

An example of organ exercise is when a giraffe stretches its neck to reach for food, which makes it lengthen. If the giraffe does not stretch its neck, it will become shorter.

Evolution factors (according to Lamarck) are:

1) adaptation to environmental conditions, due to which various changes occur in organisms;

2) inheritance of acquired characteristics.

The driving forces of evolution (according to Lamarck) consist in the desire of organisms to improve.

The main achievement of Lamarck's theory was that for the first time an attempt was made to prove the existence of evolution in the organic world in the process of ).

Similar views on the development of the organic world were expressed by Professor of Moscow University K.F.Rulier. In his theoretical positions, he went further than JB Lamarck, since he rejected the idea of ​​the desire of organisms to improve. But he published his theory later Lamarck and could not create an evolutionary theory in the form in which it was developed by Charles Darwin.

General characteristics of the evidence for the evolution of the organic world

The study of organisms over a long historical period of human development has shown that organisms have undergone changes, were in a state of constant development, that is, evolved. There are four groups of evidence for evolutionary theory: cytological, paleontological, comparative anatomical, and embryological. In this subsection, we will consider these proofs in general terms.

General characteristics of cytological evidence of the evolution of organisms

The essence of cytological evidence is that almost all organisms (except viruses) have a cellular structure. The cells of animals and plants are characterized by a general structure plan and organelles that are general in form and function (cytoplasm, endoplasmic reticulum, cell center, etc.). However, plant cells differ from animal cells in different ways of feeding and in different adaptations to the environment compared to animals.

Cells have the same chemical and elemental composition, regardless of belonging to any organism, having a specificity associated with the peculiarity of the organism.

The existence in nature of an intermediate type of unicellular organisms - flagellates, combining the characteristics of plant and animal organisms (they, like plants, are capable of photosynthesis, and like animals - of a heterotrophic way of feeding), testifies to the unity of the origin of animals and plants.

Review of embryological evidence for evolution

It is known that in individual development (ontogenesis) all organisms go through the stage of embryonic (intrauterine - for viviparous organisms) development. The study of the embryonic period of different organisms shows the common origin of all multicellular organisms and their ability to evolve.

The first embryological evidence is that the development of all (both animal and plant) organisms begins with one cell - the zygote.

The second most important proof is the biogenetic law discovered by F. Müller and E. Haeckel, supplemented by A. N. Severtsov, A. O. Kovalevsky and I. I. Shmalgauzen. This law says: "In the embryonic development of ontogeny, organisms go through the main embryonic stages of phylogenetic (historical) development of the species." Thus, individual individuals of a species, regardless of the level of its organization, go through the stage of zygote, morula, blastula, gastrula, three germ layers, organogenesis; moreover, both fish and humans have a fish-like larval stage and the human embryo has gills and gill slits (this applies to animals).

The clarification of the biogenetic law by Russian scientists refers to the fact that organisms go through the main stages of phylogenetic development, repeating the stages characteristic of the embryonic period of development, and not for the adult states of organisms.

Comparative anatomical evidence for evolution

This evidence relates to animal evolution and is based on information obtained from comparative anatomy.

Comparative anatomy is a science that studies the internal structure of various organisms in comparison with each other (this science is of the greatest importance for animals and humans).

As a result of studying the structural features of chordates, it was found that these organisms have bilateral (bilateral) symmetry. They have a musculoskeletal system with a single, common to all, structural plan (compare the human skeleton and the skeleton of a lizard or frog). This testifies to the common origin of humans, reptiles and amphibians.

Various organisms have homologous and similar organs.

Homologous organs are called organs that are characterized by a general structural plan, unity of origin, but they can have a different structure due to the performance of different functions.

Examples of homologous organs are the pectoral fin of a fish, the forelimb of a frog, a wing of a bird, and a human hand.

Similar are those organs that have approximately the same structure (external form) due to the performance of similar functions, but have a different plan of structure and different origins.

Similar organs include the burrowing limb of a mole and a bear (an insect leading an underground lifestyle), a bird's wing and a butterfly's wing, etc.

Comparative anatomical evidence also includes the presence of rudiments and atavisms in organisms.

Rudiments are residual organs that are not used by these organisms. Examples of rudiments are the appendix (caecum), coccygeal vertebrae, etc. Rudiments are the remains of those organs that were once needed, but at this stage of phylogeny have lost their meaning.

Atavisms are signs that were previously inherent and characteristic of a given organism, but at this stage of evolution have lost their meaning for most individuals, but manifested in this particular individual in its ontogeny. Atavisms include tailedness of some people, human polymastia (multi-nipple), excessive development of the hairline. Superstitious people give tails and increased development of the hairline some religious meaning, consider such people close to the devil, and in the Middle Ages they were even burned at the stake.

Paleontological evidence for evolution

Paleontology is the science of the organic world of past geological eras, that is, of organisms that once lived on Earth, but are now extinct. In paleontology, paleozoology and paleobotany are distinguished.

Paleozoology studies the remains of fossil animals, and paleobotany studies the remains of fossil plants.

Paleontology directly proves that the organic world of the Earth in different geological epochs was different, it changed and developed from primitive forms of organisms to more highly organized forms.

Paleontological research makes it possible to establish the history of the development of various forms of organisms on Earth, to reveal the related (genetic) connections between individual organisms, which contributes to the creation of a natural system of the organic world of the Earth.

In conclusion, we can conclude that the briefly considered phenomena prove that the organic world of the Earth is in a state of constant, slow, gradual development, i.e., evolution, while development proceeded and continues from the simple to the complex.

The role of heredity and variability in the evolution of the organic world

The most important factors of evolution are variability and heredity. The role of heredity in evolution is the transfer of traits, including those that have arisen in ontogeny from parents to offspring.

The variability of organisms leads to the appearance of individuals with different levels of differences from each other. Is every change that has arisen in ontogeny inherited? Probably not. Modifications that do not affect the genome are not inherited. Their role in evolution is that such changes allow the body to survive in difficult, sometimes extreme environmental conditions. So, small leaves help to reduce transpiration (evaporation), which allows the plant to survive in conditions of a lack of moisture.

An important role in the evolutionary processes is played by hereditary (mutational) variability affecting the gamete genome. In this case, the changes that have arisen are transmitted from parents to offspring, and the new trait is either fixed in the offspring (if it is useful to the body), or the organism dies if this trait worsens its adaptability to the environment.

Thus, hereditary variability "creates" material for natural selection, and heredity fixes the changes that have arisen and leads to their accumulation.

Evolution is a process of long, gradual, slow changes that ultimately lead to radical, qualitative changes, resulting in the formation of new systems, structures and species.

Historical preconditions for the emergence of evolutionary doctrine

One of the first attempts at a systematic study of living nature belongs to Aristotle (384 - 322 BC), who described about 500 species of organisms and arranged them in a certain order on the "ladder of nature." On the first stage, he placed inorganic bodies, on the second - the simplest organisms, then, at higher levels - the rest of the organisms as they become more complex. However, at the same time, he did not allow the thought of the development of lower organisms to higher ones, therefore, on the basis of his ideas, ideas arose about the constancy and immutability of existing life forms, which could vary in numbers and even die out, but were not able to change.

In the Middle Ages, these views were reflected in Christian religious dogmas and were called creationism. It was believed that all types of living organisms were created by God, and since then they have remained unchanged. At the same time, after animals and humans, God and Angels were placed on the “ladder of nature”.

First attempt at systematization

Systematization implies the unification of organisms according to similar characteristics into separate groups. The first such attempt was made by the English naturalist John Ray (1627 - 1705), who classified plants, combining them according to a number of features into genera and species.

A species is a set of individuals with similar morphophysiological characteristics, inhabiting a certain habitat, capable of interbreeding with each other and giving fertile offspring.

Genus - a set of species closely related in origin.

Classification by K. Linnaeus

Then the Swedish scientist Karl Linnaeus (1707 - 1778) expanded this classification to include all plants and animals known at that time, and proposed a unified terminology for describing organisms, which is still used today. His system of constructing the living world was of great importance for the further development of biology, although it contained many inaccuracies due to the fact that the classification was based on similarity in only one feature.

Karl Linnaeus understood that this system, in his own words, was artificial, acceptable only until a natural classification system was found. In his views, Linnaeus did not go beyond the framework of official religion, believing that "there are as many species as the Almighty created at the beginning of the world," therefore the artificiality of his system was due to the fact that it did not reflect the single origin of organisms and their evolutionary relationship. At the same time, noting the similar structural features of many organisms, he admitted the possibility of changes in species under the influence of habitat conditions and as a result of crossing of individuals of different species.