Charles Robert Darwin is a naturalist, a pioneer of the theory of the origin of life on Earth from a common ancestor, through the evolution of each species. The author of the book "The Origin of Species", the theory of the origin of man, the concepts of natural and sexual selection, the first ethological study "Expression of emotions in humans and animals", the theory of the causes of evolution.

Charles Darwin was born on 12 February 1809 in Shropshire (England) at the Darwin's Mount House, Shrewsbury. Robert Darwin, the boy's father, doctor and financier, son of the naturalist scientist Erasmus Darwin. Mother Susanne Darwin, nee Wedgwood, daughter of the artist Josiah Wedgwood. The Darwin family had six children. The family attended the Unitarian Church, but Charles's mother is a parishioner of the Anglican Church before marriage.

In 1817, Charles was sent to school. Eight-year-old Darwin got acquainted with natural science and took the first steps in collecting. In the summer of 1817, the boy's mother died. The father gave his sons Charles and Erasmus in 1818 to a boarding school at the Church of England - "Shrewsbury School".

Charles was not doing well in school. Languages ​​and literature were difficult. The boy's main passion is collecting and hunting. The morals of his father and teachers did not make Charles take up his mind, and in the end he was given up on him. Later, the young Darwin had another hobby - chemistry, for which Darwin was even reprimanded by the head of the gymnasium. Charles Darwin graduated from high school with far from brilliant results.

After graduating from high school in 1825, Charles, along with his brother Erasmus, entered the University of Edinburgh, the Faculty of Medicine. Before admission, the young man worked as an assistant in medical practice father.

Darwin studied at the University of Edinburgh for two years. During this time, the future scientist realized that medicine is not his vocation. The student stopped attending lectures and became interested in making stuffed animals. Charles's teacher in this matter was the freed slave John Edmonstone, who traveled to the Amazon with the group of the naturalist Charles Waterton.

Darwin made his first discoveries in the field of anatomy of marine invertebrates. The young scientist presented his works in March 1827 at a meeting of the Plinievsky student society, of which he had been a member since 1826. In the same society, young Darwin became acquainted with materialism. During this time he worked as an assistant to Robert Edmond Grant. He attended the course in natural history by Robert Jameson, where he received basic knowledge in geology, worked with the collections belonging to the Museum of the University of Edinburgh.

The news of the neglected studies of his son did not delight Darwin Sr. Realizing that Charles would not become a doctor, Robert Darwin insisted on admitting his son to Christ College, Cambridge University. Although the visits to the Plinyevsky Society greatly shaken Darwin's faith in the dogmas of the church, he did not oppose his father's will and in 1828 he survived entrance exams to Cambridge.

Studying at Cambridge did not fascinate Darwin too much. The student's time was occupied by hunting and horse riding. A new hobby has appeared - entomology. Charles entered the circle of insect collectors. The future scientist made friends with Cambridge professor John Stevens Henslow, who opened the door for the student to wonderful world botany. Henslow introduced Darwin to the leading natural scientists of the day.

As his final exams approached, Darwin began to force the missing material in core subjects. Ranked 10th on the basis of the results of the graduation exams.

Travels

After completing his studies in 1831, Charles Darwin remained for some time at Cambridge. He devoted time to studying Natural Theology by William Paley and Alexander von Humboldt's Personal Narrative. These books inspired Darwin to travel to the tropics to study natural sciences on practice. To implement the idea of ​​travel, Charles took a course in geology by Adam Sedgwick, and then went with the reverend to North Wales to map rocks.

Upon arrival from Wales, Darwin was waiting for a letter from Professor Henslow with a recommendation to the captain of the expedition ship of the British Royal Navy "Beagle" Robert Fitzroy. The ship at that time set off on a voyage to South America, and Darwin could take the place of a naturalist in the team. True, the position was not paid. Charles 'father strongly objected to the trip, and only the word "for" Charles' uncle, Josiah Wedgwood II, saved the situation. The young naturalist went on a trip around the world.

The journey began in 1831 and ended on October 2, 1836. The Beagle's crew carried out work on the cartographic survey of the coasts. Darwin at this time was engaged on the shore collecting artifacts for the collection on natural history and geology. He kept a full account of his observations. At every opportunity, the naturalist sent copies of the records to Cambridge. During the trip, Darwin collected an extensive collection of animals, a large proportion of which was assigned to marine invertebrates. Described geological structure a number of coasts.

Near the Cape Verde Islands, Darwin made a discovery about the influence of the time interval on geological changes, used by him in writing works on geology in the future.

In Patagonia, he discovered the fossilized remains of the ancient mammal Megatherium. The presence of mollusks next to it in the rock of modern shells testified to the recent extinction of the species. The discovery aroused interest in scientific circles in England.

Investigation of the stepped plains of Patagonia, revealing the ancient layers of the Earth, led Darwin to the conclusion that the statements in Lyell's work "about the constancy and extinction of species" were incorrect.

The Beagle crew found an earthquake off the coast of Chile. Charles saw the earth's crust rise above sea level. In the Andes, he found the shells of marine invertebrates, which led the scientist to guess about the emergence of barrier reefs and atolls due to the tectonic movement of the earth's crust.

In the Galapagos Islands, Darwin noticed differences between local animal species and mainland relatives and representatives of neighboring islands. The object of the study was the Galapagos turtles and mockingbirds.

In Australia, the strange marsupial animals and platypuses seen were so different from the animal world of other continents that Darwin seriously thought about another "creator".

With the Beagle's team, Charles Darwin visited the Cocos Islands, Cape Verde, Tenerife, Brazil, Argentina, Uruguay, and Tierra del Fuego. Based on the results of the collected information, the scientist created the works "Diary of the Investigations of a Naturalist" (1839), "The Zoology of Voyage on the Beagle" (1840), "The Structure and Distribution of Coral Reefs" (1842). Described interesting a natural phenomenon- penitentes (special ice crystals on the glaciers of the Andes).

After returning from the trip, Darwin began collecting evidence for his theory of species change. Living in a deeply religious environment, the scientist understood that his theory undermines the accepted dogmas of the existing world order. He believed in God as a supreme being, but was completely disillusioned with Christianity. His final departure from the church came after the death of his daughter Anne in 1851. Darwin did not stop helping the church and giving support to the parishioners, but when his family attended church services, he went for a walk. Darwin called himself an agnostic.

In 1838 Charles Darwin became secretary of the Geological Society of London. He held this post until 1841.

Doctrine of descent

In 1837, Charles Darwin began keeping a diary categorizing plant varieties and pet breeds. In it, he entered his thoughts on natural selection. The first notes on the origin of species appeared in 1842.

"The origin of species" is a chain of arguments supporting the theory of evolution. The essence of the doctrine is the gradual development of populations of species through natural selection. The principles outlined in the work were called "Darwinism" in the scientific community.

In 1856, the preparation of an expanded version of the book began. In 1859, 1250 copies of the work "The Origin of Species by Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life" were published. The book was sold out in two days. During Darwin's lifetime, the book was published in Dutch, Russian, Italian, Swedish, Danish, Polish, Hungarian, Spanish and Serbian languages... Darwin's works are being republished and popular today. The theory of the scientist-naturalist is still relevant and forms the basis of the modern theory of evolution.

Another important work of Darwin is "The Descent of Man and Sexual Selection." In it, the scientist developed a theory about a common ancestor in humans and modern monkeys. The scientist conducted a comparative anatomical analysis, compared the embryological data, on the basis of which he showed the similarity between humans and monkeys (simial theory of anthropogenesis).

In his book On the Expression of Emotions in Man and Animals, Darwin described man as part of an evolutionary chain. Man, as a living organism, has evolved from a lower animal form.

Personal life

Charles Darwin married in 1839. He took his marriage seriously. Before making a decision, I wrote down all the pros and cons on a sheet of paper. After the verdict "Marry-Marry-Marry" on November 11, 1838, he proposed to his cousin Emma Wedgwood. Emma is the daughter of Josiah Wedgwood II, uncle of Charles, Member of Parliament and owner of a porcelain factory. At the time of the wedding, the bride turned 30 years old. Before Charles, Emma rejected marriage proposals. The girl corresponded with Darwin during the years of travel to South America... Emma is an educated girl. She wrote sermons for a rural school, studied music in Paris with Frederic Chopin.

The wedding took place on January 29. The wedding in the Anglican Church was conducted by the brother of the bride and groom John Allen Wedgwood. The newlyweds settled in London. On September 17, 1842, the family moved to Down, Kent.

Emma and Charles had ten children. Children have reached a high position in society. Sons George, Francis and Horace were members of the Royal Society of England.

Three babies died. Darwin linked the painfulness of children with a kinship relationship between themselves and Emma (the work "Sickness of offspring from closely related crossing and the advantages of distant crossbreeding").

Death

Charles Darwin died at the age of 73 on April 19, 1882. Buried at Westminster Abbey.

After her husband's death, Emma bought a house in Cambridge. Sons Francis and Horace built houses side by side. The widow lived in Cambridge during the winter. For the summer she moved to the family estate in Kent. She died on October 7, 1896. Buried in Down, next to Darwin's brother Erasmus.

• Charles Darwin was born on the same day c.
• In the photo, Darwin looks like.
• "The Origin of Species" became so called only by the sixth reprint.

• Darwin learned new species of animals from a gastronomic point of view: he tasted dishes from armadillos, ostriches, agouti, iguanas.
• Many rare species of animals are named in honor of the scientist.
• Darwin never renounced his convictions: until the end of his days, living in a deeply religious family, he was a doubting person about religion.
• The Beagle's journey lasted five years instead of two.

Variability

Comparing many breeds of animals and varieties of plants, Darwin noticed that within any species of animals and plants, and in culture within any variety and breed, there are no identical individuals. Based on K. Linney's instructions that reindeer herders recognize every deer in their herd, shepherds recognize every sheep, and many gardeners recognize varieties of hyacinths and tulips by their bulbs, Darwin concluded that variability is inherent in all animals and plants.

Analyzing the material on the variability of animals, the scientist noticed that any change in the conditions of detention is enough to cause variability. Thus, Darwin understood variability as the ability of organisms to acquire new characters under the influence of conditions environment... He distinguished the following forms of variability:

In The Origin of Species by Natural Selection, or Conservation of Favored Breeds in the Struggle for Life (1859) and Changes in Domestic Animals and Crop Plants (1868), Darwin detailed the diversity of domesticated animal breeds and analyzed their origins. He noted the diversity of cattle breeds, of which there are about 400. They differ from each other in a number of features: color, body shape, the degree of development of the skeleton and muscles, the presence and shape of horns. The scientist studied in detail the question of the origin of these breeds and came to the conclusion that all European breeds of cattle, despite the great differences between them, descended from two ancestral forms domesticated by man.

The breeds of domestic sheep are extremely diverse, there are more than 200 of them, but they come from a limited number of ancestors - the mouflon and argali. Various breeds of domestic pigs are also bred from wild boar forms, which, in the process of domestication, have changed many features of their structure. Breeds of dogs, rabbits, chickens and other domestic animals are unusually diverse.

Of particular interest to Darwin was the question of the origin of pigeons. He proved that all existing pigeon breeds descended from one wild ancestor - the rocky (mountain) pigeon. The breeds of pigeons are so different that any ornithologist, finding them in the wild, would recognize them as independent species. However, Darwin showed their common origin based on the following facts:

• none of the species of wild pigeons, except for the rocky one, show signs of domestic breeds;
• many of the features of all domestic breeds are similar to those of the wild rock pigeon. Domestic pigeons do not build nests in trees, keeping the wild pigeon instinct. All breeds have the same behavior when courting a female;
• when crossing pigeons of different breeds, hybrids sometimes appear with signs of a wild rock pigeon;
• all hybrids between any breed of pigeon are fertile, which confirms their belonging to the same species. It is quite clear that all these numerous breeds have resulted from a change in one original form. This conclusion is also true for most domestic animals and cultivated plants.

Darwin paid much attention to the study of various varieties of cultivated plants. So, comparing various varieties of cabbage, he concluded that they were all bred by man from one wild species: they differ in the shape of the leaves with similar flowers and seeds. Ornamental plants, such as different varieties of pansies, produce a variety of flowers, and their leaves are almost the same. Gooseberry varieties have a variety of fruits, and the leaves are almost the same.

Causes of variability... Showing the variety of forms of variability, Darwin explained the material causes of variability, which are environmental factors, conditions for the existence and development of living beings. But the influence of these factors is not the same depending on the physiological state of the organism, the stage of its development. Among the specific causes of variability, Darwin singles out:

• direct or indirect (through the reproduction system) influence of living conditions (climate, food, care, etc.);
• functional organ tension (exercise or non-exercise);
• crossing (the appearance in hybrids of characteristics that are not characteristic of the original forms);
• changes due to the correlative dependence of parts of the body.

Among the various forms of variability for the evolutionary process, hereditary changes are of paramount importance as the primary material for variety, breed and speciation - those changes that are fixed in subsequent generations.

Heredity

By heredity, Darwin understood the ability of organisms to preserve their species, varietal and individual characteristics in their offspring. This feature was well known and represented a hereditary variation. Darwin analyzed in detail the importance of heredity in the evolutionary process. He drew attention to cases of uniformity of hybrids of the first generation and splitting of traits in the second generation, he was aware of heredity associated with sex, hybrid atavisms and a number of other phenomena of heredity.

At the same time, Darwin noted that the study of variability and heredity, their immediate causes and patterns is associated with great difficulties. Science of that time could not yet give a satisfactory answer to a number of important questions. The works of G. Mendel were also unknown to Darwin. Only much later began extensive studies of variability and heredity, and modern genetics took a giant step in the study of the material foundations, causes and mechanisms of heredity and variability, in the causal understanding of these phenomena.

Darwin attached great importance to the presence of variability and heredity in nature, considering them to be the main factors of evolution, which has an adaptive nature. [show] .

The adaptive nature of evolution

Darwin in his work "The Origin of Species ..." noted the most important feature of the evolutionary process - the continuous adaptation of species to the conditions of existence and the improvement of the organization of the species as a result of the accumulation of adaptations. However, he noted that the adaptability of a species, developed by selection to the conditions of existence, although it is important for the self-preservation and self-reproduction of species, cannot be absolute, it is always relative and useful only in those environmental conditions in which species exist for a long time. The shape of the body, respiratory organs and other features of fish are advisable only in conditions of life in water and are not suitable in terrestrial life. The green coloration of the locust disguises insects on green vegetation, etc.

The process of expedient adaptation can be traced on the example of any group of organisms that have been sufficiently studied in evolutionary terms. Horse evolution is a good example.

Studying the ancestors of the horse made it possible to show that its evolution was associated with the transition from life in forests on swampy soil to life in open dry steppes. The known ancestors of the horse have changed in the following directions:

• increased growth due to the transition to life on open spaces(high growth is an adaptation to the expansion of the horizon in the steppes);
• an increase in running speed was achieved by a lightening of the skeleton of the leg and a gradual decrease in the number of toes (the ability to run quickly has a protective value and makes it possible to more effectively find water bodies and forage lands);
• intensification of the grinding function of the dental apparatus as a result of the development of ridges on the molars, which was especially important in connection with the transition to feeding on tough grass vegetation.

Naturally, along with these changes, correlative ones also took place, for example, elongation of the skull, changes in the shape of the jaws, physiology of digestion, etc.

Along with the development of adaptations, the so-called adaptive diversity manifests itself in the evolution of any group. It lies in the fact that against the background of the unity of the organization and the presence of common systematic features, representatives of any natural group of organisms always differ in specific features that determine their adaptability to specific living conditions.

In connection with life in similar living conditions, unrelated forms of organisms can acquire similar adaptations. For example, such systematically distant forms as a shark (class Pisces), ichthyosaurus (class Reptiles) and dolphin (class Mammals) have a similar appearance, which is an adaptation to the same living conditions in a certain environment, in this case in water. The similarity between systematically distant organisms is called convergence (see below). In sedentary protozoa, sponges, coelenterates, annelids, crustaceans, echinoderms, ascidians, the development of root-like rhizoids is observed, with the help of which they are strengthened in the ground. Many of these organisms are characterized by a stalked body shape, which allows, when sedentary, to soften the shock of waves, tremors of fish fins, etc. All sedentary forms tend to form clusters of individuals and even coloniality, where the individual is subordinate to a new whole - a colony, which reduces the likelihood of death as a result of mechanical damage.

In different living conditions, related forms of organisms acquire different adaptations, i.e. from one ancestral form, two or more species can arise. This process of divergence of species in different ecological conditions Darwin called divergence (see below). An example of this is the finches on the Galapagos Islands (west of Ecuador): some feed on seeds, others on cacti, and others on insects. Each of these forms differs from the other in the size and shape of the beak and could arise as a result of divergent variability and selection.

Even more diverse are the adaptations of placental mammals, among which there are terrestrial forms with a fast run (dogs, deer), species leading an arboreal lifestyle (squirrel, monkey), animals living on land and in water (beavers, seals), living in air environment ( the bats), aquatic animals (whales, dolphins) and species with an underground lifestyle (moles, shrews). All of them descend from a single primitive ancestor - an arboreal insectivorous mammal (Fig. 3).

Adaptation is never absolutely perfect due to the lengthy process of accumulation of adaptations. Change in relief, climate, composition of fauna and flora, etc. quickly enough can change the direction of selection and then adaptations developed in some conditions of existence lose their significance in others, for which new adaptations begin to be developed again. At the same time, the number of some species decreases, while the more adapted ones increase. The newly adapted organisms may retain the previous signs of adaptation, which in the new conditions of existence are not decisive for self-preservation and self-reproduction. This allowed Darwin to talk about the inexpediency of the signs of adaptation, which were found in the organization and behavior of organisms quite often. This is especially clear when the behavior of organisms is not determined by their way of life. So, the webbed feet of geese serve as an adaptation for swimming and their presence is advisable. However, mountain geese also have webbed feet, which is clearly inappropriate given their lifestyle. The frigate bird usually does not land on the ocean surface, although, like mountain geese, it has webbed feet. It is safe to say that membranes were necessary and useful to the ancestors of these birds, as well as to modern aquatic birds. Over time, the descendants adapted to the new living conditions, lost the habit of swimming, but they retained their swimming organs.

It is known that many plants are sensitive to temperature fluctuations and this is a reasonable response to the seasonal periodicity of vegetation and reproduction. However, such sensitivity to temperature fluctuations can lead to mass death of plants if the temperature rises in the fall, stimulating the transition to re-flowering and fruiting. This excludes the normal preparation of perennial plants for winter and they die when cold weather sets in. All of these examples are indicative of relative expediency.

The relativity of expediency manifests itself with a significant change in the conditions of existence of the organism, since in this case the loss of the adaptive nature of a particular feature is especially evident. In particular, the rational arrangement of burrows with an outlet at the water level in the desman is destructive in winter floods. Erroneous reactions are often observed in migratory birds. Sometimes waterfowl arrive in our latitudes before the opening of reservoirs and the lack of food at this time leads to their mass death.

Expediency is a historically emerging phenomenon under the constant action of natural selection, and therefore it manifests itself in different ways at different stages of evolution. In addition, the relativity of fitness provides the possibility of further restructuring and improvement of the adaptations available for a given type, i.e. the infinity of the evolutionary process.

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However, having substantiated the question of variability and heredity as factors of evolution, Darwin showed that by themselves they still do not explain the emergence of new animal breeds, plant varieties, species, and their adaptability. Darwin's great merit is that he developed the doctrine of selection as the leading and directing factor in the evolution of domestic forms (artificial selection) and wild species (natural selection).

Darwin established that as a result of selection, a species change occurs, i.e. selection leads to divergence - deviation from the original form, divergence of characters in breeds and varieties, the formation of a large variety of them [show] .

The divergent nature of evolution

The principle of divergence, that is, the divergence of characteristics of varieties and breeds, Darwin developed on the example of artificial selection. Later, he used this principle to explain the origin of animal and plant species, their diversity, the emergence of differentiation between species, substantiate the doctrine of the monophyletic origin of species from a common root.

The divergence of the evolutionary process is deduced from the facts of multidirectional variability, predominant survival and reproduction in a number of generations of extreme variants that compete with each other to a lesser extent. Intermediate forms, for the life of which similar food and habitats are needed, are in less favorable conditions and, therefore, die out faster. This leads to a greater gap between the extreme options, the formation of new varieties, which later become independent species.

Divergence under the control of natural selection leads to the differentiation of species and their specialization. For example, the genus of tits unites species that live in different places (biotopes) and eat different foods (Fig. 2). The divergence of butterflies of the whitewash family went towards the adaptation of caterpillars to eating various food plants - cabbage, turnips, rutabagas and other wild cruciferous plants. Among buttercups, one species live in water, while others live in swampy areas, forests or meadows.

On the basis of similarity, as well as common origin, taxonomy unites closely related plant and animal species into genera, genera into families, families into orders, etc. Modern taxonomy is a reflection of the monophyletic nature of evolution.

The principle of divergence developed by Darwin has an important biological significance... He explains the origin of the wealth of life forms, the ways of development of numerous and more diverse habitats.

A direct consequence of the divergent development of most groups within similar habitats is convergence - the convergence of characters and the development of outwardly similar features in forms of different origins. A classic example of convergence is the similarity of the body shape and organs of movement in a shark (fish), ichthyosaur (reptile) and dolphin (mammal), ie, the similarity of adaptations to life in water (Fig. 3). There are similarities between placental and marsupial mammals, between the smallest hummingbird and the large hummingbird moth. Convergent similarity of individual organs occurs in unrelated animals and plants, i.e. is built on a different genetic basis.

Progress and regression

Darwin showed that the inevitable consequence of divergent evolution is the progressive development of organic nature from simple to complex. This historical process of increasing organization is well illustrated by paleontological data, and also reflected in the natural system of plants and animals, which unites the lower and higher forms.

Thus, evolution can take different paths. The main directions of evolutionary development and morphophysiological patterns of evolution were elaborated in detail by Acad. A.N. Severtsov (see macroevolution).

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Artificial selection

Analyzing the characteristics of domestic animal breeds and varieties of cultivated plants, Darwin drew attention to the significant development in them of precisely those traits that are appreciated by man. This was achieved by the same method: when breeding animals or plants, breeders for reproduction left those specimens that most fully satisfied their needs and from generation to generation accumulated changes beneficial to humans, i.e. carried out artificial selection.

By artificial selection, Darwin understood a system of measures to improve existing and create new breeds of animals and plant varieties with useful (economically) hereditary traits and distinguished the following artificial selection forms:

Purposeful breeding of a breed or variety. When starting work, the breeder sets himself a specific task in relation to those traits that he wants to develop in this breed. First of all, these signs must be economically valuable or satisfy the aesthetic needs of a person. The traits with which the breeder works can be both morphological and functional. These may include the nature of the behavior of animals, for example, pugnaciousness in fighting cocks. Solving the task set for himself, the breeder selects from the already available material all that is best, in which the signs of interest to him are manifested, at least to a small extent. Selected individuals are kept in isolation to avoid unwanted interbreeding. The breeder then selects pairs to cross. After that, starting from the first generation, he conducts a rigorous selection better material and the rejection of the one that does not meet the requirements.

Thus, methodical selection is a creative process that leads to the formation of new breeds and varieties. Using this method, the breeder, like a sculptor, sculpts new organic forms according to a premeditated plan. Its success depends on the degree of variability of the initial form (the more the features change, the easier it is to find the necessary changes) and the size of the original batch (in a large batch, there are greater opportunities for choice).

Methodological selection in our time, using the achievements of genetics, has significantly improved and became the basis of modern theory and practice of animal and plant breeding.

Unconscious selection carried out by a person without a specific, predetermined task. This is the oldest form of artificial selection, the elements of which were already used by primitive people. With unconscious selection, a person does not set a goal to create a new breed, variety, but only leaves it to the tribe and mainly reproduces the best individuals. So, for example, a peasant who has two cows, wanting to use one of them for meat, will slaughter the one that gives less milk; of hens, he uses the worst layers for meat. In both cases, the peasant, while preserving the most productive animals, conducts directed selection, although he does not set himself the goal of developing new breeds. It is this primitive form of selection that Darwin calls unconscious selection.

Darwin emphasized the special importance of unconscious selection from a theoretical point of view, since this form of selection also sheds light on the process of speciation. It can be seen as a bridge between artificial and natural selection. Artificial selection was a good model on which Darwin deciphered the process of shaping. Darwin's analysis of artificial selection played an important role in substantiating the evolutionary process: firstly, he finally confirmed the position of variability: secondly, he established the main mechanisms of morphogenesis (variability, heredity, predominant reproduction of individuals with useful traits) and, finally, showed the ways of developing expedient adaptations and divergence of varieties, breeds. These important prerequisites paved the way for a successful solution to the problem of natural selection.

The doctrine of natural selection as a driving and directing factor in the historical development of the organic world -
central part of Darwin's theory of evolution .

At the heart of natural selection is the struggle for existence - the complex relationships between organisms and their relationship with the environment.

Struggle for existence

In nature, there is a constant tendency towards unlimited reproduction of all organisms in geometric progression. [show] .

According to Darwin's calculations, one poppy box contains 3 thousand seeds, and a poppy plant, which grew from one seed, gives up to 60 thousand seeds. Many fish annually lay up to 10-100 thousand eggs, cod and sturgeon - up to 6 million.

The Russian scientist K. A. Timiryazev gives the following example to illustrate this point.

Dandelion, according to rough estimates, gives 100 seeds. Of them on next year 100 plants can grow, each of which will also give 100 seeds. This means that with unhindered reproduction, the number of descendants of one dandelion could be represented as a geometric progression: the first year - 1 plant; the second - 100; the third - 10,000; tenth year - 10 18 plants. For the resettlement of the descendants of one dandelion obtained in the tenth year, an area is required 15 times the area of ​​the globe.

This conclusion can be reached if we analyze the reproductive ability of a wide variety of plants and animals.

However, if you count, for example, the number of dandelions per a certain area meadows for several years, it turns out that the number of dandelions changes little. A similar situation is observed among representatives of the fauna. Those. "geometric progression of reproduction" is never carried out, because between organisms there is a struggle for space, food, shelter, competition in choosing a sexual partner, a struggle for survival with fluctuations in temperature, humidity, lighting, etc. In this struggle, the majority of those born die (eliminated, removed) without leaving offspring, and therefore in nature the number of individuals of each species remains constant on average. In this case, the surviving individuals turn out to be the most adapted to the conditions of existence.

The discrepancy between the number of individuals born and the number of individuals that survive to a mature state as a result of complex and varied relationships with other living things and environmental factors Darwin based his doctrine of the struggle for existence or the struggle for life [show] ... At the same time, Darwin was aware that this term was unfortunate and warned that he was using it in a broad metaphorical sense, and not literally.

Darwin reduced various manifestations of the struggle for existence to three types:

1. interspecific struggle - the relationship of an organism with individuals of other species (interspecific relationships);
2. intraspecific struggle - the relationship between individuals and groups of individuals of the same species (intraspecific relationships)
3. struggle with the conditions of the inorganic environment - the relationship of organisms and species with the physical conditions of life, the abiotic environment

Intraspecific relationships are also quite complex (relationships between individuals of different sexes, between parental and daughter generations, between individuals of the same generation in the process of individual development, relationships in a flock, herd, colony, etc.). Most of the forms of intraspecific relationships are important for the reproduction of the species and the maintenance of its numbers, ensuring the change of generations. With a significant increase in the number of individuals of a species and restrictions on the conditions for their existence (for example, with thickened plantings of plants), an acute interaction arises between individual individuals, which leads to the death of some or all of the individuals or their elimination from reproduction. The extreme forms of such relations include intraspecific struggle and cannibalism - eating individuals of their own species.

The fight against the conditions of the inorganic environment arises depending on climatic and soil conditions, temperature, humidity, illumination and other factors affecting the vital activity of organisms. In the process of evolution, animal and plant species develop adaptations to life in a particular environment.

It should be noted that the three named basic forms of the struggle for existence in nature are not carried out in isolation - they are closely intertwined, due to which the interrelationships of individuals, groups of individuals and species are multifaceted and rather complex.

Darwin was the first to reveal the content and meaning of such important concepts in biology as "environment", "external conditions", "interconnection of organisms" in the process of their life and development. Academician I.I.Shmalgauzen considered the struggle for existence to be one of the main factors of evolution.

Natural selection

Natural selection, in contrast to artificial selection, is carried out in nature itself and consists in the selection within the species of the most adapted individuals to the conditions of a particular environment. Darwin discovered a certain commonality in the mechanism of artificial and natural selection: in the first form of selection, the conscious or unconscious will of man is embodied in the results, in the second, the laws of nature prevail. In both cases, new forms are created, however, with artificial selection, despite the fact that variability affects all organs and properties of animals and plants, the resulting animal breeds and plant varieties retain traits that are useful for humans, but not for the organisms themselves. On the contrary, natural selection preserves individuals in which the changes are beneficial for their own existence in the given conditions.

In "The Origin of Species" Darwin gives the following definition of natural selection: "I called the preservation of useful individual differences or changes and the elimination of harmful ones natural selection, or the experience of the fittest" (c) - (Darwin Ch. The Origin of Species. - M., L .; Selkhozgi, 1937, p. 171.). He warns that "selection" should be understood as a metaphor, as a fact of survival, and not as a conscious choice.

So, natural selection is understood as a process constantly occurring in nature, in which the most adapted individuals of each species survive and leave offspring, and the less adapted die. [show] ... The extinction of the unadapted is called elimination.

Consequently, as a result of natural selection, the species that are most adapted to those specific environmental conditions in which their life takes place survive.

Constant changes in environmental conditions for a long time are the cause of a variety of individual hereditary changes, which can be neutral, harmful or beneficial. As a result of the competition in life in nature, there is a constant selective elimination of some individuals and the predominant survival and reproduction of those that, changing, have acquired useful features. As a result of crossing, a combination of traits of two different forms occurs. So from generation to generation, minor beneficial hereditary changes and their combinations accumulate, which over time become characteristic features populations, varieties, species. At the same time, due to the law of correlation, simultaneously with the strengthening of adaptive changes in the body, a restructuring of other signs also occurs. Selection constantly affects the entire organism, its external and internal organs, on their structure and function. This is the manifestation of the creative role of selection (see microevolution).

Darwin wrote: “Speaking metaphorically, we can say that natural selection daily, hourly, investigates the smallest changes all over the world, discarding the bad ones, preserving and making up the good ones, working inaudibly, invisibly, wherever and whenever an opportunity presents itself, to improve of each organic being in relation to the conditions of its life, organic and inorganic "(c) - (Darwin Ch. The origin of species. - M., L .; Selkhozgi, 1937, p. 174.).

Natural selection is a historical process. Its effect is manifested through many generations, when subtle individual changes are summed up, combined and become characteristic adaptive features of groups of organisms (population, species, etc.).

Sexual selection... As a special kind of intraspecific natural selection, Darwin singled out sexual selection, under the influence of which secondary sex characteristics are formed (bright color and various decorations of males of many birds, sex differences in the development, appearance, behavior of other animals) in the process of active relationships between the sexes of animals, especially during the breeding season ...

Darwin distinguished two types of sexual selection:

1. fight between males for a female
2. active searches, the choice of males by females, males only compete with each other in order to excite females who choose the most attractive males

The results of both types of sexual selection differ among themselves. In the first form of selection, strong and healthy offspring appear, well-armed males (the appearance of spurs, horns). With the second, such secondary sexual characteristics of males as the brightness of the plumage, the features of mating songs, the smell emitted by the male, which serves to attract the female, is enhanced. Despite the seeming inexpediency of such signs, since they attract predators, such a male has an increased chance of leaving offspring, which turns out to be beneficial to the species as a whole. The most important result of sexual selection is the appearance of secondary sex characteristics and the associated sexual dimorphism.

Natural selection can occur at different rates in different circumstances. Darwin notes circumstances favorable to natural selection:

• the large number of individuals and their diversity, which increases the likelihood of beneficial changes;
• rather high frequency of manifestation of undefined hereditary changes;
• the intensity of reproduction and the rate of generational change;
• unrelated crossing, which increases the range of variability in the offspring. Darwin notes that cross-pollination is rare even among self-pollinating plants;
• isolation of a group of individuals, preventing them from crossing with the rest of the mass of organisms in a given population;

  Comparative characteristics artificial and natural selection
  Indicator for comparison	Evolution of cultural forms (artificial selection)	Evolution of natural species (natural selection)
  Selection material	Individual hereditary variability
  Selection factor	Person	Struggle for existence
  The nature of the selection action	Accumulation of changes in a successive series of generations
  Selection action speed	Acts quickly (methodical selection)	Acts slowly, evolution is gradual
  Selection results	Creation of forms useful to man; formation of breeds and varieties	Education of adaptations to the environment; formation of species and larger taxa

• the wide distribution of the species, since at the same time, at the boundaries of the range, individuals meet with different conditions and natural selection will go in different directions and increase the intraspecific diversity.

In the very general view the scheme of action of natural selection, according to Darwin, is as follows. Due to the indefinite variability inherent in all organisms, individuals with new characters appear within the species. They differ from ordinary individuals of this group (species) in terms of needs. Due to the difference between old and new forms, the struggle for existence leads some of them to elimination. As a rule, less evaded organisms, which became intermediate in the process of divergence, are eliminated. Intermediate forms find themselves in conditions of intense competition. This means that uniformity, which heightens competition, is harmful, and that evading forms are in a better position and their numbers are increasing. The process of divergence (divergence of signs) occurs constantly in nature. As a result, new varieties are formed and such separation of varieties eventually leads to the appearance of new species.

Thus, the evolution of cultural forms proceeds under the influence of artificial selection, the components (factors) of which are variability, heredity and human creative activity. The evolution of natural species is carried out due to natural selection, the factors of which are variability, heredity and the struggle for existence. The comparative characteristics of these forms of evolution are given in the table.

Darwin's speciation process

The emergence of new species was presented by Darwin as a long process of accumulation of beneficial changes, increasing from generation to generation. The scientist took small individual changes as the first steps of speciation. Their accumulation through many generations leads to the formation of varieties, which he considered as steps on the path of the formation of a new species. The transition from one to the other occurs as a result of the accumulating action of natural selection. A variety, according to Darwin, is a nascent species, and a species is a pronounced variety.

In the course of evolution, several new ones may arise from one parent species. For example, view A as a result of divergence can give rise to two new types B and C, which in turn will be the basis for other types (D, E), etc. Of the changed forms, only the most deviated varieties survive and give birth to offspring, each of which again gives rise to a fan of changed forms, and again the most deviated and better adapted ones survive. Thus, step by step, there are increasing differences between the extreme forms, finally developing into differences between species, families, etc. The reason for the divergence, according to Darwin, is the presence of indefinite variability, intraspecific competition, and the multidirectional nature of the selection action. A new species can also arise as a result of hybridization between two species (A x B).

Thus, Charles Darwin in his teaching combines positive sides the doctrine of the form of K. Linney (recognition of the reality of species in nature) and J.-B. Lamarck (recognition of the boundless variability of species) and proves the natural way of their formation based on hereditary variability and selection. He proposed four criteria for the species - morphological, geographical, ecological and physiological. However, as Darwin pointed out, these characteristics were not enough for a clear classification of species.

A species is a historical phenomenon; it arises, develops, reaches full development, and then, under changed environmental conditions, disappears, giving way to other species, or itself changes, giving rise to other forms.

Extinction of species

Darwin's doctrine of the struggle for existence, natural selection and divergence satisfactorily explains the question of the extinction of species. He showed that in the constantly changing conditions of the external environment, some species, decreasing in number, must inevitably perish and give way to others, better adapted to these conditions. Thus, in the process of evolution, the destruction and creation of organic forms are constantly carried out as a necessary condition for development.

The reason for the extinction of species can be various unfavorable environmental conditions for a species, a decrease in the evolutionary plasticity of a species, a lag in the rate of species variability or the rate of change in conditions, and narrow specialization. More competitive species are crowding out others, as the fossil record convincingly testifies.

Evaluating the evolutionary theory of Charles Darwin, it should be noted that he proved historical development living nature, explained the ways of speciation as a natural process and actually substantiated the formation of adaptations of living systems as a result of natural selection, first revealing their relative nature. Charles Darwin explained the main reasons and driving forces evolution of plants and animals in culture and wildlife. Darwin's teaching was the first materialistic theory of the evolution of living things. His theory played a large role in strengthening historical perspective on organic nature and largely determined the further development of biology and all natural science.

CHARLES DARWIN DARWIN, CHARLES ROBERT (DARWIN, CHARLES (ROBERT) 1809-1882), ENGLISH NATURALIST AND WRITER, FOUNDER OF THE TEACHING ON THE ORIGIN OF ANIMALS AND PLANTS FROM HER. BORN FEBRUARY 12, 1809 IN SHRUSBURY. FOR TWO YEARS I STUDYED AT THE UNIVERSITY OF EDINBURGH MEDICINE, TO WHICH AT THE END OF THE END I FOUND ITSELF UNSUITABLE. In 1827 he entered the University of Cambridge, where he had studied theology for three years, but then decided that he had no inclination to do this.

Charles Darwin was born on February 12, 1809 in the family of a doctor. While studying at the Universities of Edinburgh and Cambridge, Darwin gained in-depth knowledge of zoology, botany and geology, skills and a taste for field research. The book "Principles of Geology" by the outstanding English geologist Charles Lyell played an important role in the formation of his scientific outlook. Lyell argued that the modern appearance of the Earth took shape gradually under the influence of the same natural forces that are still active today. Darwin was familiar with the evolutionary ideas of Erasmus Darwin, Lamarck, and other early evolutionists, but he did not find them convincing.

In 1831, after graduating from university, he went on a round-the-world voyage on the expedition ship of the Royal Navy "Beagle" as a naturalist and returned to England only in October. During the trip, Darwin visited Tenerife, Cape Verde, the coast of Brazil, Argentina, Uruguay, on Tierra del Fuego, Tasmania and the Cocos Islands and made a huge number of observations in zoology, botany, geology, paleontology, anthropology and ethnography. He presented their results in the works Diary of a Naturalist's Research, The Zoology of Voyages on the Beagle, The Structure, Distribution of Coral Reefs, etc.

Upon his return from the voyage, Darwin begins to ponder the problem of the origin of species. He considers various ideas, including the idea of ​​Lamarck, and rejects them, since none of them provides an explanation for the facts of the amazing adaptability of animals and plants to the conditions of their habitat. What the early evolutionists thought was initially given and did not require explanation seems to Darwin the most important issue... It collects data on the variability of animals and plants in nature and under domestication conditions. Many years later, recalling how his theory arose, Darwin wrote: “I soon realized that selection was the cornerstone of human success in creating useful races of animals and plants. However, for some time it remained a mystery to me how selection could be applied to organisms that live in natural conditions. "

After reading Malthus's book On Population, in October 1838, Darwin had the idea of ​​the origin of species through natural selection. He worked on it for 20 years. In 1856, on Lyell's advice, he began to prepare his work for publication. In 1858, the young English scientist Alfred Wallace sent Darwin the manuscript of his article "On the tendency of varieties to unlimited deviation from the original type." This article presented the idea of ​​the origin of species by natural selection. Darwin was ready to refuse to publish his work, but his friends the geologist C. Lyell and the botanist G. Hooker, who had long known about Darwin's idea and got acquainted with the preliminary sketches of his book, convinced the scientist that both works should be published simultaneously.

In 1859, he published his book The Origin of Species by Natural Selection, in which he hypothesized that the existing species of animals and plants are not constant, but changeable and evolved from some other species through gradual evolutionary changes. Man, in his opinion, descended from a monkey.

The basic principles of the evolutionary theory of Charles Darwin. 1. Within each species of living organisms, there is a huge range of individual hereditary variability in morphological, physiological, behavioral and any other characteristics. This variability can be continuous, quantitative, or discontinuous, qualitative, but it always exists.

3. Vital resources for any kind of living organisms are limited, and therefore there should be a struggle for existence either between individuals of the same species, or between individuals of different species, or with natural conditions... In the concept of "struggle for existence" Darwin included not only the actual struggle of an individual for life, but also the struggle for success in reproduction. 2. All living organisms multiply exponentially.

4. Under the conditions of the struggle for existence, the most adapted individuals survive and give offspring, having those deviations that accidentally turned out to be adaptive to the given environmental conditions. This is a fundamentally important point in Darwin's argumentation. Deviations do not arise in a directional response to the action of the environment, but randomly. Few of them prove to be useful in specific conditions. The descendants of the surviving individual who inherit the beneficial deviation that allowed their ancestor to survive are more adapted to the given environment than other members of the population. 5. Survival Darwin called the predominant reproduction of adapted individuals natural selection.

On these postulates, flawless from the point of view of logic and supported by a huge number of facts, was created modern theory evolution. Darwin's main merit is that he established the mechanism of evolution that explains both the diversity of living beings and their amazing expediency, adaptation to the conditions of existence. This mechanism is a gradual natural selection of random undirected hereditary changes. Major advances in evolutionary biology in last years were achieved thanks to active use in evolutionary research of ideas and methods molecular genetics and developmental biology.

1. Within each species of living organisms, there is a huge range of individual hereditary variability in morphological, physiological, behavioral and any other characteristics. This variability can be continuous, quantitative, or discontinuous, qualitative, but it always exists. 2. All living organisms multiply exponentially.

3. Vital resources for any kind of living organisms are limited, and therefore there should be a struggle for existence either between individuals of the same species, or between individuals of different species, or with natural conditions. In the concept of "struggle for existence" Darwin included not only the actual struggle of an individual for life, but also the struggle for success in reproduction. 4. Under the conditions of the struggle for existence, the most adapted individuals survive and give offspring, having those deviations that accidentally turned out to be adaptive to the given environmental conditions. This is a fundamentally important point in Darwin's argumentation. Deviations do not arise in a directional response to the action of the environment, but randomly. Few of them prove to be useful in specific conditions. The descendants of the surviving individual who inherit the beneficial deviation that allowed their ancestor to survive are more adapted to the given environment than other members of the population.

5. Survival and preferential reproduction of adapted individuals Darwin called natural selection. 6. Natural selection of individual isolated varieties in different conditions of existence gradually leads to divergence (divergence) of the characteristics of these varieties and, ultimately, to speciation. On these postulates, flawless from the point of view of logic and supported by a huge number of facts, the modern theory of evolution was created.

Preconditions for the emergence of Charles Darwin's theory. V late XVIII v. the development of capitalism in England required an increase raw material base... Industry began to develop at a high rate and Agriculture... During this period, much attention was paid to breeding work with the aim of developing new varieties and breeds. New breeds of cattle, horses, pigs, dogs, pigeons were bred. New varieties of vegetable, fruit and berry plant crops have been obtained.
In the XIX century. great advances have been made in the field of geology, physics, chemistry. Achievements in the field of science were: the discovery of the theory of the structure of organic compounds by AM Butlerov (1861); creation Periodic table chemical elements D.M. Mendeleev (1869); proof by the English geologist C. Lyell that geological changes are not caused by accidental catastrophes, but occur under the influence of climate, etc. As a result of the study of the development of the embryos of vertebrates, the existence of the branchial arch and gill circulation in the embryos of birds and mammals was proved. The proof of the kinship of fish, birds, mammals and the emergence of their ancestors on land was a huge success in science. Discoveries in various fields of natural science (geology, paleontology, biogeography, embryology, comparative anatomy, cytology, etc.) were in no way consistent with the view of the immutability of nature.

Great English natural scientist, founder of the evolution of the organic world. It was based on materials collected during a 5-year voyage on the Beagle ship. Proved the origin of man from the lower stages of animals. The main factor of evolution was determined by variability, selection, the struggle for existence. He established the cause and laws of the evolution of the organic world. Works: "The Origin of Species", "Natural Selection", "Domestic Animals", "The Origin of Man, Sexual Selection", "Worms", etc.

Rice. 13. Map of Charles Darwin's round-the-world voyage on the ship "Beagle" (1831-1836)

An important role in the creation of Charles Darwin's theory was played by the materials collected by him during his round-the-world voyage on the Beagle ship (Fig. 13). Although the primacy in the discovery of evolutionary theory did not belong to Darwin, he proved that evolution is a process of variability of organisms. He was also the first to prove the existence of an evolutionary process, explaining the development of nature by the influence of natural laws.
C. Darwin set himself the goal of explaining the similarities and differences between species and the reasons for the diversity of living organisms. He was especially interested in the species composition of plants and animals of the Galapagos Islands. He collected 20 species of plants from the Asteraceae family. On the island, he discovered 25 species of birds, including 13 species of finches (Fig. 14).

Rice. 14. Variety of finches in the Galapagos Islands

The Galapagos Islands are located 700 km from the coast of South America. Therefore, of the birds that live on the island, 85% of the species are not found anywhere else.
Charles Darwin noticed that finches from the Galapagos Islands differ from previously seen finches from the coast of South America. After observing them for three weeks, he was convinced that the main difference between birds is in their beaks. Darwin concluded that despite the fact that all of these 13 bird species descended from one common ancestor, the reason for the change in beaks is the feeding habits. The beaks of finches feeding on hard seeds are very thick; those who eat berries and fruits are long and thin; flowers feeding on insects and nectar - sharp as an awl, etc. There are finches, similar to woodpeckers, picking out insects from under the bark of trees.

Works and biography of Charles Darwin. Charles Robert Darwin was born in England on February 12, 1809 in the town of Shrewsbury to the family of a doctor. Father Robert Darwin was a renowned physician. After leaving school in 1826, he entered the medical faculty of the University of Edinburgh, but Darwin was more interested not in medicine, but in wildlife. While still at school, he was fond of collecting collections of worms, crayfish, beetles, snails (molluscs) along the banks of ponds and rivers. Later, in 1828, at the request of his father, he entered
theological faculty of the University of Cambridge. Here he also continued to collect materials about wildlife.
In 1831, upon his return from a geological excursion from North Wales, Charles Darwin received a letter from a professor at the University of Cambridge, John Gensloh. In the letter he informs about the round-the-world voyage of the ship "Beagle" and asks Charles Darwin to participate in it as a naturalist. Being on a journey for 5 years, at the age of 22, Charles Darwin collects a huge amount of material. The ship "Beagle" was heading on a round-the-world voyage for topographic surveys (mapping) of the coast of South America and the islands The Pacific... In 1836 the ship returns from a round-the-world voyage. Darwin, having studied the collected materials, begins work on the book "The Origin of Species". He then works to collect data on the variability of crops and domestic animals.
His main works: "The Origin of Species" (1859); "Change of animals and cultivated plants" (1868); The Descent of Man (1871); Insectivorous Plant (1875), Action of Cross-Pollination and Self-Pollination (1876); "Pollination of orchids" (1877) and others. During his trip around the world, Charles Darwin noticed the property of all animals and plants to change under the influence of environmental conditions. Then he proceeds to collect materials about their variability in artificial and natural conditions. As a result of studying the causes of the diversity of plant varieties and animal breeds, he determined that the change in nature is associated only with natural laws, and proved that man himself creates varieties and breeds through hereditary variability and artificial selection.
Charles Darwin, investigating the causes of the origin of new species, drew attention to the intensity of reproduction of organisms in nature.
He gave many examples of the intensive reproduction of organisms in order to preserve their offspring.
It has been proven that any species of plants and animals have the property of multiplying exponentially. At the same time, he noticed that any couple leaves a lot of offspring, but not all reach puberty. During the breeding season, most offspring die from the action various factors(lack of food, unfavorable environmental conditions, etc.). On the basis of these factors, Charles Darwin concluded that there is a constant struggle for existence in nature. He proved that the survival of some individuals giving offspring, and the extinction of others, is the result of natural selection. The process of preserving individuals with traits that are useful for them under certain conditions Darwin called natural selection, or the survival of the fittest.
Thus, Charles Darwin identified three factors in the historical development of the organic world: hereditary variability, struggle
for existence and natural selection. As a result of the interconnection of hereditary variability, the struggle for existence, natural selection, species adapt to the conditions of the external environment and change. So, these are the main provisions of the evolutionary theory of Charles Darwin.

1. The basis for the emergence of the teachings of Charles Darwin was the scientific background.
2. Materials collected during a round-the-world voyage on the ship "Beagle".
3. Determination of three factors in the development of the organic world: hereditary variability, the struggle for existence and natural selection.
4. What are the main social prerequisites for the emergence of Darwin's teachings.
5. What are the main works of Charles Darwin.
6. What did Charles Darwin find in plants and animals during his trip around the world on the Beagle?
7. What achievements are known in the field of natural science in the 19th century?
8. What expedition materials collected during the trip helped Charles Darwin prove that new species appear in nature? Give examples.
9. With what factors did Charles Darwin connect the historical development of the organic world?
10. Compare the original ancestor of finches (Figure 14) with other species.
11. How do you understand the term intensive reproduction? Why do most of the offspring die?
12. What are the results of natural selection?

Sketch this table on a separate sheet. Fill it out by entering accordingly scientific discoveries scientists who contributed to the emergence of the teachings of Darwin.

* Test your knowledge!
Review questions. Chapter 2. Foundations of evolutionary teaching

1. The name of the term meaning historical development, change, progress.
2. The scientist is the founder of the evolutionary doctrine.
3. The scientist who wrote treatise"History of Animals".
4. A student of Aristotle who studied plant and animal biology.
5. Swedish scientist who proposed the systematics of the organic world.
6. The largest systematic group in the system of K. Linnaeus.
7. How many orders did K. Linnaeus classify mammals?
8. The scientist who laid the scientific foundations for the development of the organic world before Charles Darwin.
9. How many classes did JB Lamarck divide invertebrates into?
10. The scientist who proposed in the XIX century. theory of the structure of organic compounds.
11. The name of the ship on which Charles Darwin made a round-the-world trip.

Today, few would deny Darwin's enormous contribution to biology. The name of this scientist is familiar to every adult. Many of you can summarize Darwin's contributions to biology. However, only a few will be able to tell in detail about the theory he created. After reading the article, you will be able to do it.

Achievements of the ancient Greeks

Before describing Darwin's contribution to biology, let us tell in a few words about the achievements of other scientists on the way to the discovery of the theory of evolution.

Anaximander, an ancient Greek thinker, dating back to the 6th century BC. e. said that man came from animals. His ancestors were allegedly covered in scales and lived in water. A little later, in the 4th century. BC BC, Aristotle noted that nature preserves useful traits that randomly appear in animals in order to make them more viable in the future. And brothers who do not have these signs die. It is known that Aristotle created the "ladder of beings". He arranged the organisms in order from the simplest to the most complex. This staircase began with stones and ended with a man.

Transformism and creationism

The Englishman M. Hale in 1677 first used the term "evolution" (from the Latin "deployment"). He designated them the unity of the historical and individual development of organisms. In biology in the 18th century, the doctrine of how changed different kinds plants and animals. It was contrasted with creationism, according to which God created the world and all species remain unchanged. The supporters of transformism include the French scientist Georges Bufford, as well as the English researcher Erasmus Darwin. The first theory of evolution was proposed by Jean-Baptiste Lamarck in his 1809 work "The Philosophy of Zoology". However, it was Charles Darwin who revealed its true factors. The contribution to biology of this scientist is invaluable.

Merit of Charles Darwin

He owns evolutionary theory scientifically grounded. He presented it in a work entitled "The Origin of Species by Natural Selection". This book was published by Darwin in 1859. The contribution to biology can be briefly described as follows. Darwin believed that - hereditary variability, as well as the struggle for existence. Under conditions of struggle, natural selection becomes the inevitable result of this variability, which is the predominant survival of the most adapted individuals of a particular species. Thanks to their participation in reproduction, beneficial hereditary changes accumulate and accumulate, as noted by Charles Darwin.

His contribution to biology was recognized by scientists who continued research in this direction. The development of science further confirmed that the Darwinian theory is correct. Therefore, today the terms "evolutionary doctrine" and "Darwinism" are often used as synonyms.

So, we have briefly characterized Darwin's contribution to biology. We propose to consider in more detail the theory he created.

Observations that inspired Darwin's theory of evolution

First began to think about the reasons why there are certain similarities and differences between species, Charles Darwin. His contribution to biology, which we have briefly described, was far from immediate. First, it was necessary to study the achievements of predecessors, as well as make several trips. It was they who prompted the scientist to important thoughts.

He made the main find in South America, in geological deposits. These are the skeletons of giant incomplete teeth, very similar to modern sloths and armadillos. In addition, Darwin was impressed by the study of animal species that live on the Scientist discovered on these volcanic islands of recent origin, close species of finches, which are similar to the mainland ones, but have adapted to various food sources - flower nectar, insects, hard seeds. Charles Darwin concluded that these birds came to the island from the mainland. And the changes that have occurred to them are explained by adaptation to new conditions of existence.

Charles Darwin posed the question that environmental conditions play a role in speciation. The scientist observed a similar picture off the coast of Africa. Inhabiting animals, despite a certain similarity with the species inhabiting the mainland, still differ from them in very significant features.

Darwin could not explain the creation of species and the developmental features of the rodent tuko-tuko, described by him. These rodents live underground in burrows. They have sighted cubs, which subsequently go blind. All these and many other facts have significantly shaken the scientist's belief in the creation of species. Darwin, returning to England, set himself an ambitious task. He decided to solve the question of the origin of the species.

Major works

Darwin's contribution to the development of biology is presented in several of his works. In 1859, in his work, he summarized the empirical material of breeding practice and biology, contemporary to him. In addition, he used the results of his observations made while traveling. His circumnavigation of the world shed light on various species.

Charles Darwin supplemented his main work "The Origin of Species ..." with factual materials in his next book, published in 1868. It is known as "Changing Domestic Animals and Crop Plants". In another work, written in 1871, the scientist put forward the hypothesis that man is descended from an ape-like ancestor. Today, many agree with the assumption made by Charles Darwin. Contribution to biology allowed him to become a great authority in the scientific world... Many people even forget that the origin of man from a monkey is just a hypothesis, which, although very likely, is still not fully proven.

The property of heredity and its role in evolution

Note that the Darwinian theory is based on the property of heredity, that is, the ability of organisms to repeat the types of metabolism and, in general, individual development in a number of generations. Together with variability, heredity ensures the diversity and constancy of life forms. It is the basis for the evolution of the entire organic world.

Struggle for existence

"Struggle for existence" is a concept that is one of the main concepts in the theory of evolution. Charles used it to refer to the relationships that exist between organisms. In addition, Darwin used it to describe the relationship between abiotic conditions and organisms. Abiotic conditions lead to the survival of the fittest individuals and the death of the less fit.

Two forms of variability

With regard to variability, Darwin identified two main forms. The first is a certain variability. This is the ability of all individuals of a particular species under certain environmental conditions to respond in the same way to given conditions (soil, climate). The second form - Its nature does not correspond to the observed changes in external conditions. Uncertain variability in modern terminology is called mutation.

Mutation

The mutation, unlike the first form, is hereditary. According to Darwin, in subsequent generations, the minor changes observed in the first are amplified. The scientist emphasized that the decisive role in evolution belongs to uncertainty variability. It is usually associated with deleterious mutations or neutral ones, but there are also those that are called promising.

Evolution mechanism

According to Darwin, the inevitable result of hereditary variability and the struggle for existence is the survival and reproduction of new organisms that are most adapted to living in the corresponding environment. And in the course of evolution, the death of the unadapted occurs, that is, natural selection. Its mechanism operates in nature similarly to breeders, that is, vague and insignificant individual differences are formed, from which the necessary adaptations in organisms are then formed, as well as differences between species.

About all this, as well as about many other things, Charles Darwin spoke and wrote. The contribution to biology, briefly described, is not limited to what we have described. However, in general terms, his main achievements were characterized. Now you can elaborate on Darwin's contributions to biology.