The theory of evolution in the middle of the last century produced the same effect as the theory of Copernicus in its time. It was a scientific revolution, and not only in the field of biology. Evolutionism has changed the image of man. If the Copernican revolution changed the idea of ​​the spatial order in the Universe, indicating to man a different place than before, then Darwin revised the temporal order. The place and role of man in nature were radically revised by the efforts of Copernicus and Darwin.

Charles Darwin (1809-1882) initially dabbled in medicine, a church career, until in 1831 he was on board the English ship Beagle, which was sailing around the world, as a naturalist. The travelers departed Devon Port on December 27, 1831, and returned to Falmouth on October 2, 1836. In 1839, Darwin published travel diaries in "A naturalist's journey around the world". During this more than important scientific journey, Darwin studied "Fundamentals of Geology" Charles Lyell (1797-1875). The history of the earth was explained by Lyell by the action of forces that changed the earth's surface (floods, volcanic eruptions, downpours, landslides, etc.), by the same laws that

Darwin: On the Origin of Species 233

explain the facts of the present. So there were doubts about the biblical version of the origin of the earth and living beings.

On the Galapagos Islands (an archipelago in the Pacific Ocean), Darwin discovered a group of finches that had, depending on their habitat, beaks of different proportions. It was obvious that species characteristics were capable of changing gradually, just as it was also obvious that all the endless cases of adaptation (woodpecker, tree frog, etc.) are difficult to explain only by environmental conditions. Upon his return to England, Darwin collects information about various types of animals and plants both in nature and at home, consults with gardeners and pastoralists and carefully records the data obtained.

A lot of time passed before the scientist came to the conclusion that it was with the help of selection that a person learned to grow the necessary and useful species of plants and animals. It remained to find out how selection occurs in the natural environment. Starting systematic research in October 1838, Darwin read Malthus' writings on population in his spare time. Understanding well the importance of the factor of the struggle for existence, no matter what kind of form was discussed, he was suddenly struck by the conjecture that under the influence of changing circumstances, most likely, favorable and corresponding changes are preserved, and inappropriate forms are destroyed. This is how the idea of ​​a new theory was born, says the scientist in his Autobiography. It took more than twenty years to develop it.

In 1857, the first publication of evolutionary theory appeared in the Journal of the Meetings of the Linnean Society. A b 1859 book by Darwin "The Origin of Species by Means of Natural Selection" saw the light. It said that the environment produces a selection of the most acceptable hereditary changes. Selection, in other words, is expressed in evolutionary orientation, because it determines the adaptation of organisms to the environment. Evolution can be interpreted as a series of adaptations, each of which a certain species fixes or loses under the pressure of selection over a long period of time.

The success of the book is evidenced by the fact that 1250 copies of the first edition were sold on the first day, as well as 3000 copies of the second edition that soon appeared. What is the theoretical novelty of the book, which had such an unprecedented success?

Darwin identified five types of evidence for evolutionary theory. 1. Evidence regarding heredity and cultivation, considering the changes brought about by domestication.

2. Evidence related to geographical distribution.

3. Archaeologically obtained evidence. 4. Evidence related to the mutual similarity of living beings. 5. Evidence obtained from embryology and from the study of vestigial organs.

234 Development of the sciences in the 19th century

AT "The Origin of Species" we read: many are convinced that “each species was created one independently of the other. But my way of thinking is more consistent with what is known from the laws imprinted in matter by the Creator: the appearance and distribution of the past and present inhabitants of the world is due to secondary causes similar to those that determine the birth and death of an individual. When I consider living beings not as special creations, but rather as direct descendants of a few beings who lived long ago, in the first centuries of the Silurian period, they appear to me ennobled.

The laws "imprinted in matter", according to Darwin, are quite simple: development through reproduction; variability associated with direct and indirect effects of living conditions, use and non-use of organs; an increase in numbers and, as a result, an intensification of the struggle for existence; divergence of characteristic features and prevalence of less perfect forms. Consequently, in the process of natural struggle, something beyond all expectations is born - the formation of developed animals. This is a grandiose conception of life - from initially one or a few forms to more and more complex. "Rotating according to its immutable laws of gravity, the planet evolves, starting from simple ones, to come to infinitely beautiful and amazing forms."

If, under changing conditions of life, organic beings show individual differences in almost every part of their organization, and this cannot be disputed; if, due to the geometric progression of reproduction, a fierce struggle for life is tied up at any age, in any year or season, and this, of course, cannot be disputed; and also if we remember the infinite complexity of the relations of organisms both among themselves and to their living conditions, and the infinite variety of useful features of structure, constitution and habits arising from these relations - if we take all this into account, it would be extremely improbable that never changes beneficial to the organism possessing them were manifested, in the same way as numerous changes beneficial to man arose. But if changes beneficial to any organism ever appear, the organisms possessing them will, of course, have the best chance of remaining in the struggle for life, and, by virtue of the strict principle of heredity, they will show a tendency to transmit them to posterity. This principle of conservation, or survival of the fittest, I have called Natural Selection. It leads to the improvement of every being in relation to the organic and inorganic conditions of his life, and consequently, in most cases, to what may be considered an ascent to a higher level of organization. Nevertheless, simply organized, lower forms will last long, if only they are well adapted to their simple living conditions.

Natural selection, based on the principle of inheritance of traits at an appropriate age, can change an egg, a seed, or a young organism as easily as an adult organism. In many animals, sexual selection has probably aided ordinary selection by ensuring that the strongest and best-adapted males have the most numerous offspring. Sexual selection also develops traits that are exclusively useful to males in their struggle or rivalry with other males, and these traits, depending on the predominant form of heredity, will be transmitted to both sexes or only one. Natural selection also leads to a divergence of characters, because the more organic beings differ in structure, habits and constitution, the greater their number can exist in a given area - proof of which we can find by paying attention to the inhabitants of any small piece of land and to organisms naturalized in a foreign country.

Natural selection, as has just been noted, leads to a divergence of characters and a significant extermination of less improved and intermediate forms of life. On the basis of these principles, both the nature of affinity and the usual presence of well-marked boundaries between innumerable organic beings of every class throughout the world can be easily explained. Truly amazing is the fact - although we are not amazed at it, it is so common - that all animals and all plants at all times and everywhere are connected in groups subordinate to one another, as we observe at every step, and just so that varieties of the same species are most closely related to each other; less closely and unevenly related species of the same genus, forming departments and subgenera; even less close are the species of different genera and, finally, the genera, representing various degrees of mutual proximity, expressed by subfamilies, families, orders, subclasses and classes.

If the species were created independently of one another, then it would be impossible to find an explanation for this classification; but it is explained by heredity and the complex action of natural selection, which entails extinction and divergence of characters, as shown in our diagram.

The affinity of all beings belonging to the same class is sometimes depicted in the form of a large tree. I think this comparison is very close to the truth. The green, budding branches represent extant species, while those from previous years correspond to a long line of extinct species. In each period of growth, all growing branches form shoots in all directions, trying to overtake and drown out neighboring shoots and branches; in the same way, species and groups of species have at all times overpowered other species in the great struggle for life. The ramifications of the trunk, dividing at their ends first into large branches, and then into smaller and smaller branches, were themselves once - when the tree was still young - shoots dotted with buds; and this connection of former and modern buds, by means of branching branches, perfectly presents to us the classification of all modern and extinct species, which unites them into groups subordinate to other groups. Of the many shoots that sprang up before the tree had yet grown into a trunk, perhaps only two or three survived and have now grown into large branches that carry the rest of the branches; so it was with the species that lived in long past geological periods - only a few of them still living today left behind changed descendants.

Since the beginning of the life of this tree, many more and less large branches withered and fell off; these fallen branches of various sizes represent entire orders, families and genera, which at present do not have living representatives and are known to us only from fossil remains. Here and there, in a fork between the old branches, a scrawny shoot breaks out, survived by chance and still green at its top: such is some Ornithorhynchus or Lepidosiren, to some extent connecting by their affinity two large branches of life and saved from a fatal competition thanks to a protected habitat. As buds, by virtue of growth, give rise to new buds, and these, if only strong, turn into shoots, which, branching, cover and drown out many withered branches, so, I believe, it was also with the great Tree of Life, which filled its dead fallen branches of the bark of the earth and covered its surface with their ever-spreading and beautiful branches.

Comments

The position of the eyes in such semi-aquatic animals as the hippopotamus, the crocodile, and the frog is extremely similar: it is convenient for observing above the water when the body is immersed in water. However, convergent similarity in one trait does not affect most other organizational features, and the hippopotamus remains a typical mammal, the crocodile is a reptile, and the frog is an amphibian. In evolution, the re-emergence of individual features is possible (caused by a similarly directed action of natural selection, but the emergence of unrelated forms that are the same throughout their organization is impossible (the rule of irreversible evolution).

The convergence of traits, caused by a similar direction of natural selection, when it is necessary to live in some kind of similar environment, sometimes leads to surprising similarities. Sharks, dolphins and some ichthyosaurs are very similar in body shape. Some cases of convergence still mislead researchers. So, until the middle of the XX century. hares and rabbits were assigned to the same order of rodents on the basis of similarities in the structure of their dental systems. Only detailed studies of the internal organs, as well as biochemical features, made it possible to establish that hares and rabbits should be separated into an independent order of lagomorphs, phylogenetically closer to ungulates than to rodents.

The specificity of the genetic program of each organism is determined by the sequence of links in the DNA chain - nucleotides. The more similar (homologous) DNA sequences are, the more closely related organisms are. In molecular biology, methods have been developed to quantify the percentage of homology in DNA. So, if the presence of DNA homology among humans is taken as 100%, humans and chimpanzees will have about 92% homology. Not all homology values ​​occur with the same frequency.

The figure shows the discreteness of the degrees of kinship in vertebrates. The lowest percentage of homology characterizes the DNA of representatives of different classes (1) such as birds - reptiles (lizard, turtles), fish and amphibians (5-15% homology). From 15 to 45% DNA homology in representatives of different orders within the same class (2), 50-75% in representatives of different families within the same order (3). If the compared forms belong to the same family, their DNA contains from 75 to 100% homology (4). Similar distribution patterns have been found in the DNA of bacteria and higher plants, but the numbers are quite different. According to DNA divergence, the genus of bacteria corresponds to the order, and even the class of vertebrates. When V. V. Menshutkin (I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry) simulated the process of loss of homology in DNA on a computer, it turned out that such distributions arise only if evolution proceeds according to Darwin - by selecting extreme options with the extinction of intermediate forms.

One of the first phylogenetic trees of the animal world, drawn by E. Haeckel (1866) under the influence of Charles Darwin's ideas. Relationships and the taxonomic rank of individual groups of organisms today we imagine differently (see, for example, Fig. XI-2, XI-3), but the images of the relationship of groups in the form of a tree remain today the only ones that reflect the history of the development of related groups of organisms.

10 geniuses of science Fomin Alexander Vladimirovich

Darwin's evolutionary theory. "The Origin of Species"

Darwin's evolutionary theory. "The Origin of Species»

As we wrote above, notes on the origin of species, Darwin began back in 1837. There were also paleontological finds discovered in South America, and observations of the modern fauna of the New World, and Galapagos studies, and data on domesticated species, embryological observations, and much more. All these facts convinced Darwin long ago that the species inhabiting the Earth were gradually changing. But meanwhile, the scientist saw the failure of existing evolutionary hypotheses. Neither the training of organs, nor the internal desire of organisms for improvement, according to Darwin, could lead to the emergence of many perfect and complex adaptations that are very often found in wildlife:

“However, it was equally obvious that neither the action of environmental conditions, nor the will of organisms (especially when it comes to plants) is not able to explain the countless cases of excellent adaptation of organisms of all kinds to their lifestyle, for example, the fitness of a woodpecker or tree frog to tree climbing or seed adaptation to dispersal by means of hooks or flyers.

Quite quickly, Darwin realized that selection plays an important role in the creation of new varieties of plants and animal breeds. But he could not immediately transfer this idea to the conditions of natural nature.

A significant role in the formation of the scientist's views was played by Malthus' book "On the Population", which he read back in 1838. Malthus in his book derives the law of population, according to which the rate of population growth far exceeds the rate of increase in the production of means of subsistence. Accordingly, there is a struggle between people for the distribution of these funds. Darwin saw a simple biological analogy: the ability of biological species to reproduce exceeds the number of individuals that can survive. The next logical step was the idea of ​​natural selection. Darwin realized that as a result of the struggle for existence, individuals with traits that are advantageous under given conditions survive. The result of the accumulation of such characters is the emergence of new species.

Darwin made the first draft of his theory in 1842. The notes were made in pencil and amounted to 35 pages. By 1844, the summary of the theory had expanded to 230 pages. The scientist highly appreciated his work and understood its significance. Fearing that his life might be unexpectedly interrupted due to illness, in the same 1844, he wrote something similar to a will for his wife, where he asked, in the event of his sudden death, to transfer records on the theory of species to some scientist who could bring them in order and publish. To the scientist who would undertake this work, Darwin bequeathed 400-500 pounds and all the income from the proposed publication.

As we already wrote, in 1846 our hero began to study barnacles, and the theory of species temporarily faded into the background. And so, in 1854, when the second volume of the Monograph of the Barnacles subclass was published, Darwin set about the main work of his life. He began work on his famous book On the Origin of Species. In the autumn of 1854, the scientist engaged in a long and painstaking work to put in order a huge number of his notes on this problem.

Darwin conceived a grandiose work:

“At the beginning of 1856, Lyell advised me to state my views in sufficient detail, and I immediately set about doing this on a scale three or four times the volume into which my Origin of Species subsequently poured out - and yet it was only an extract from the materials I have collected.

By 1858, Darwin had written 10 chapters, about half of his intended work. But then thunder struck: an event occurred that the scientist did not expect. The young and certainly talented scientist Alfred Wallace, who at that time was studying the nature of the Malay Archipelago and Southeast Asia, sent his small work “On the tendency of varieties to an unlimited deviation from the original type” for consideration by Darwin. Wallace's essay contained a summary of evolutionary ideas, which Darwin was engaged in a detailed and extensive description. Wallace asked a senior colleague to review his work and, if approved, forward it to Lyell. Thus, despite the fact that Darwin created his theory much earlier than Wallace, the priority of his discovery was threatened. Lyell and Hooker convinced Darwin that, along with Wallace's work, extracts from an 1844 paper and Darwin's letter to the American botanist Gray, in which he outlined the foundations of his theory, should be published. Here is what the scientist himself wrote about this:

“At first I really didn’t want to go for it: I thought that Mr. Wallace might consider my act completely unacceptable - I didn’t know then how much generosity and nobility in the character of this man. Neither the extract from my manuscript nor the letter to Asa Gray was intended for publication and was badly written. On the contrary, Mr. Wallace's essay was distinguished by excellent presentation and complete clarity.

Alfred Wallace really showed great nobility. He wrote:

“I don’t have that tireless patience when collecting numerous, most diverse facts, that amazing ability to draw conclusions, that exact and rich physiological knowledge, that wit in determining the plan of experiments and that dexterity in their implementation, finally - that incomparable style - clear and in at the same time convincing and precise - in a word, all those qualities that make Darwin a perfect and, perhaps, the most capable person for the enormous work that he undertook and completed.

Wallace not only recognized the priority of Darwin, but also became an active propagandist of his theory. Thus, after Darwin's death in 1889, Wallace published the book Darwinism, in which he reviewed the development of evolutionary theory since the publication of On the Origin of Species. However, Wallace did not agree with Darwin on everything. For example, he denied the importance of sexual selection and the inheritance of acquired traits. It must be said that he was right in the second objection. The relationship between Darwin and Wallace can be safely called the standard of nobility and scientific ethics. In addition to evolutionary ideas, Wallace made a great contribution to the study of the nature of South America, the Malay Archipelago and Southeast Asia. He is considered one of the founders of zoogeography.

But back to the events of 1858. Wallace's article and excerpts from Darwin's work did not resonate in scientific circles. The scientific world paid very little attention to the publications. On the advice of his friends, Darwin set about preparing ready-made materials on the origin of species for publication. The work was interrupted by bouts of illness and hydropathic treatment. However, in November 1859 the first edition of The Origin of Species by Means of Natural Selection, or the Preservation of the Fit for the Struggle for Life, saw the light of day. According to some reports, by the time of publication, Lyell and Hooker had already made good publicity for the book in the scientific community. The first edition (1250 copies) sold out in one day. The second edition (3000 copies) also did not stale. Even during Darwin's lifetime, The Origin of Species was translated into almost all European languages ​​and even into Japanese. Moreover, an article was published in Hebrew, which claimed that Darwin's theory was contained in the Old Testament. According to the scientist, in England by 1876 (the year Darwin completed his autobiography), 16,000 copies of The Origin of Species had been sold.

The success of the book was complete, which cannot be said about the theory presented in it. An extensive scientific controversy began. At first, Darwin collected reviews of his book, but when the collection increased to 265 copies, he stopped adding to it. In studying critical reviews, Darwin divided them into two categories: “... I must say that my critics almost always treated me fairly, leaving aside those of them who did not have scientific knowledge, because they are not worth talking about. My views have often been grossly distorted, bitterly challenged and ridiculed, but I am convinced that for the most part all this was done without treachery.

Interestingly, various modern religious figures still seek to distort evolutionary theory in order to discredit it in the eyes of their potential followers. At the same time, serious modern theologians find it possible to combine the Christian faith and evolutionary teaching. This view was shared by both the leader of the Catholic Church, John Paul II, and the famous Orthodox priest and theologian Alexander Men.

But back to the events of the middle of the XIX century. As early as November 1859, a scathingly critical article appeared in the Ateneum magazine, the author of which argued that Darwin's theory of evolution was detrimental to the cause of faith. At the same time, some people dear to Darwin also joined in the criticism. So, his teacher, the geologist Sedgwick, met the theory with hostility. He did not want to acknowledge her materialism. Darwin was not very offended by the criticism, but he was greatly upset by the distortion of theory associated with it. He himself, due to illness, could not speak in face-to-face discussions about the validity of the theory, but we already know that even before the appearance of the first edition of On the Origin of Species, he had many followers and supporters who began to ardently defend Darwinism.

On June 30, 1860, a dispute took place in Oxford between supporters of Darwin's theory and creationists. The debate brought together more than 700 people. Officially, a scientific meeting was convened in order to hear a report by the American scientist Draper "The mental development of Europe, considered in connection with the views of Mr. Darwin." But in the scientific and pseudo-scientific world they knew that Bishop Wilberforce, an ardent opponent of Darwinism, would be present at the meeting. And no one doubted that the report would turn into a heated discussion. Darwin's theory was defended by Thomas Huxley and Joseph Hooker. The priest did not possess natural science knowledge, while his opponents were excellent scientists. Without going into details, it should be said that the evolutionists won. But this fight was not the last. There were many more clashes to come. And the supporters of Darwinism had to face much more prepared opponents than Bishop Wilberforce, who put forward much more serious arguments. We will tell about one of them.

In 1867, Darwin's theory of evolution received a very serious blow. This was done by the Scottish engineer Fleming Jenkin. Jenkin's argument went something like this: if some representative of a species becomes the owner of a useful trait, then this trait, when crossed with other individuals of the species, will disappear, dissolve in the swamp of the average. This objection was so serious that Darwin dubbed it "Jenkin's nightmare." The modern "synthetic theory of evolution" explains "Jenkin's nightmare" with the help of inheritance laws. A gene carrying a particular trait is preserved in the genotypes of the population. In individuals that possess this gene, it will manifest itself in full if the gene is dominant, or it will remain until the moment of meeting with the same gene if the gene is recessive. . In any case, it will remain in the population as a whole and sooner or later will be subjected to selection.

Interestingly, now scientists have returned to the “Jenkin nightmare” again. This objection is invalid if the trait is inherited by only one gene. But modern observations show that most of the important adaptive traits are realized through the combined action of a whole group of genes. And for such features, the explanation of the synthetic theory of evolution is not suitable. So the “Jenkin nightmare” passed through the entire 20th century and overtook the ideas of Darwin. But in our time, of course, this argument no longer casts doubt on the very fact of evolution. He does not refute the ideas of Darwin as a whole and does not diminish the merits of the scientist. "Jenkin's Nightmare" and some other considerations show that the modern synthetic theory of evolution is not complete and requires further development.

But back to Darwin's biography. Unable to participate in scientific disputes, the scientist continued to work hard.