Darwinism

Darwinism, the doctrine of C. Darwin concerning the origin of the organic world, including humans, from simpler forms through slow development. Evidence for evolution. In support of his viewpoint, D. presented such an enormous amount of data that against the fact of evolution, almost no one now objects. The quantity of this data increases daily. The first group of facts confirming evolution pertains to the field of paleontology. Geology proves that the earth's layers formed gradually, accumulating one upon another. In each of these layers are buried the remains of organisms that lived on them. If the organic world had not changed along with the development of the earth, then the fossilized forms or their impressions in all layers of the earth would have to be identical. Paleontology, however, proves that each geological layer is characterized by its specific fossil forms, and the lower the layer, the simpler the forms contained within it. These data not only testify to the fact of the variability of the organic world; they also show the direction of this process. The path of evolution is especially clearly revealed in vertebrates. Among vertebrates, fish are the first to appear in the ancient layers of the earth's crust, above them come amphibians, then reptiles, and still higher, birds. Last of all, in the highest layers of the earth, mammals appear. Remains of humans are first encountered in the layers of the beginning of the glacial period, i.e., in deposits that accumulated much later than those layers in which the first mammals begin to appear. But the data of paleontology are not exhausted by the testimony of such enormous stages of evolution. Often they provide us with pictures of smaller steps in evolution. Such are, for example, the studies of Huxley on fossil crocodiles. The latter are separated from their reptilian ancestors by a vast span of time, but, going back through geological stages, we encounter fossil forms that connect these series. The three currently living genera of crocodiles (Crocodilus, Alligator and Gavialis) are found in the Eocene, another genus close to them (Butlersuchus) has been discovered in the Cretaceous deposits. From the Cretaceous to the Lias (Lower Jurassic epoch) is distributed another group of genera with characteristics intermediate between modern crocodiles and more ancient forms (Belodon and Stagonolepis), found in even more ancient formations, in the Triassic. The latter have some characteristics of lizards, especially the New Zealand Hatteria, as well as some similarity with Dinosauria, reptiles approaching birds to some degree. Particularly brilliant evidence for evolution, paleontology provides on the example of the fossil ancestors of the modern horse, discovered mainly by Marsh in the Tertiary deposits of America. The modern horse sharply differs from other families of mammals in the structure of its limbs and teeth. The horse's limbs are equipped with only one broad third toe, covered with a hoof. From the second and fourth toes, only small rudiments remain, while the first and fifth have disappeared without a trace. The fossil material vividly portrays the evolutionary path of our horse from a primitive, low five-toed animal (Eohippus), so different from the modern horse that, if it were not for the gradually increasing intermediate four- and three-toed forms (Orohippus, Mesohippus, Miohippus, Protohippus, Pliohippus), it would hardly be possible to guess that one animal is the ancestor of the other. The later the layer of earth in which the ancestor of the horse is found, the closer it approaches the modern species. Primitive five-toed animals are gradually replaced by four-toed ones, which in turn give way to three-toed ones, which in their turn yield place to modern species. A similar picture of gradual evolution is also presented by the teeth of the horse and many other of its characteristics. The transitional fossil forms discovered by paleontology not only show the evolutionary path of individual species, but often fill the gap between major modern taxonomic units. Such is, for example, Archaeopteryx—the first bird, situated on the boundary between lizard and bird. The second group of evidence for evolutionary theory draws from comparative anatomy. Comparing homologous organs of various animals, we encounter, along with the striking diversity in the details of the structure of these organs, the unity of their basic plan. Such are, for example, the limbs in different mammals: man, gorilla, cow, whale, seal, mole, bat, chicken, pigeon, eagle. Comparing these limbs, we establish that, despite the diversity in particulars, they are all built according to one type, consist of similar parts arranged in the same order. Let us take the pectoral fins of a whale. From the outside, it is almost impossible to find any similarity between them and the forelimbs of any mammal. A more thorough study of these organs, however, reveals in the fin a bony skeleton analogous to the same skeleton of the forelimbs of other mammals and birds. The pectoral fin of a whale consists of one humerus, two forearm bones, several wrist bones, five metacarpal bones, and five rows of small finger bones. As for the caudal fin of the whale, it lacks such a skeleton: the caudal fin is a skin fold and contains exclusively caudal vertebrae. Consequently, it has no relation to the limbs of the whale and represents a new formation in the process of evolution. The hind limbs in most whales have completely disappeared, leaving only parts of the pelvis. Only some species, for example, the Greenland whale, are equipped, in addition to the pelvis, with short femur and tibia bones, hidden inside. The front flippers of seals not only in their internal structure but also in external form correspond to the human hand. They have retained the external division into fingers, although connected by a membrane. The fingers of the seal are even equipped with claws. The caudal fin of the seal contains the same parts of the skeleton as the hind limbs of other mammals. Consequently, its origin sharply differs from the origin of the corresponding fin in the whale. The general plan of the structure of the front paddle-like flippers in the penguin—a bird excellently adapted to aquatic life—coincides with the plan of the structure of the wings in other birds. The front flippers of the whale and penguin, although they coincide in the general plan of their structure, still differ from each other to the same degree that the forelimb of a mammal differs from the wing of a bird. The unity of plan in the midst of diversity in details finds its explanation only in the common origin of these organs. All these animals obviously descended from the same ancestor, which possessed limbs corresponding to the general plan of the limbs of the animals mentioned above. The third kind of evidence for evolution is provided by embryology. Many animals, which differ in the mature state, are so similar to each other in the early stages of embryonic development that they are difficult to distinguish from one another. For example, the human embryo in the early stages of development is difficult to distinguish from the embryos of other mammals. It, like the embryos of all mammals, has gill slits, is provided with a tail, and is covered with down (lanugo). As is known, externally in the whale the neck is not visible: the body of the whale as it were directly passes into the head. In the whale embryo, however, the neck is distinctly visible. With further development of the embryo, the skin under the occipital region as if strongly stretches, relaxing under the chin, and the head thus, along with the growth of the embryo, more and more passes into a direct continuation of the body. The larval state of many organisms, differing from the mature state of the same creatures, also testifies to evolution. The gill-breathing tadpoles, from which later develop lung-breathing frogs, show from what ancestors modern amphibians originated. The symmetrical structure of the body, as well as the symmetrical arrangement of the eyes in the flounder at the early stages of its development, its mode of life and method of obtaining food during this period show that it did not always have such a structure as we see in adult flounders at the present time. In embryonic development, the animal as it were intensively in general outline repeats the long evolutionary path of its ancestors: ontogeny repeats phylogeny (see Biogenetic law). The fourth group of evidence confirming the fact of evolution consists of rudiments, or vestigial organs. In humans there are several hundred of these rudiments (for example: ear muscles, remnant of the third eyelid, wisdom teeth). A rudiment of great importance is the vermiform appendix of the cecum, which in humans, unlike other mammals, even undergoes retrogressive development: in a newborn the cecum is shorter than the large intestine approximately ten times, while in the adult the corresponding ratio is about ¹/₂₀. Rudiments are found not only in humans but in all organisms. The remnants of fingers on the limbs of the modern horse, mentioned above, are the same rudiments. The characteristic feature of these organs is that they have either completely lost their former functional activity or have significantly weakened it.

The presence of rudimentary organs in one organism or another becomes understandable if we assume that this organism descended from ancestors that had a different form, in which these organs functioned normally. In other words, they clearly indicate the evolution of the organism. The fifth type of evidence that evolutionary theory draws from is the geographical distribution of organic life. Studying the current fauna and flora of the earth, we find that each systematic group is distributed in specific areas, and the distribution of certain animals and plants across the land is limited by known boundaries. The same can be said of fossils. Moreover, the fossils of a particular area are much closer in their organization to organisms still living in this area than to contemporary extinct animals and plants from other areas. It goes without saying that individual systematic groups of organisms may occupy the same habitat. Even more so, many of these groups are in such close interdependence that isolated habitation of these groups is impossible. Such is, for example, the dependence between certain insects and the plants that these insects pollinate. Comparing different regions of the earth by their animal population, we notice that some large systematic units, for example orders and families, are found only in Africa, others only in South America, and still others in Australia, etc. This fact makes it possible to divide all land into several large regions, so-called faunal kingdoms. The latter by no means coincide with the continents known to us. For example, for mammals, three large kingdoms have been established: 1) Arctogea, covering all of Europe, Asia, Africa, and the larger part of North America, 2) Notogea, occupying part of North America and all of South America, and 3) Notogea, extending throughout Australia with New Guinea, New Zealand, and Oceania. Each of these regions is characterized by its specific fauna. Thus, in Arctogea there are certain orders of prosimians and proboscideans not found in Notogea; in Notogea, for example, there is a special order of edentates not found in other regions, while Notogea is the homeland of egg-laying platypuses and almost all marsupials. Each of these regions in turn can be divided into smaller regions with their characteristic fauna. It is self-evident that the animal population of the northern forests of Europe and Asia differs not only from that of tropical Africa but also from southern and central Europe and Asia, despite the fact that all these areas constitute the same faunal kingdom. Therefore, each kingdom is divided into separate regions, and the latter into provinces. In Europe, for example, three provinces are distinguished: the extreme northern, or boreal, the forest, or central European, and the Mediterranean. As we move from north to south, the animal population of Europe also changes, with one species and genus being replaced by another. For example, three related genera of deer are distributed across these three provinces as follows: in the boreal province, the reindeer inhabits it; in the central European province, the so-called noble deer; and in the Mediterranean, they are replaced by the fallow deer. The change in population when moving from one province to another can also be traced in other genera and species (bears, foxes, hares, etc.). Such a distribution of organisms across the earth becomes understandable only from an evolutionary point of view. Not all species arose simultaneously. Each species arose in some locality from another species (as evidenced by the fossils of this geographical zone) through gradual change of the original species, which either became extinct or continued to exist for some time alongside the newly arisen species. Newly formed species were unable to spread indefinitely across the entire earth: on their path of distribution, they encountered natural barriers—physical, climatic, organic. From this point of view, for example, the characteristic specificity of Australia's animal population becomes understandable. At one time, marsupials had a very wide distribution on earth. From them, placental mammals arose. Subsequently, marsupials were displaced by placental mammals. But precisely at this time, Australia had already become separated from neighboring continents by a wide sea. Placental mammals could not conquer Australia, so marsupials remained the dominant forms here. The further development of both of these faunal kingdoms proceeded along their own special paths, depending directly on the organization of these animal forms, i.e., on their genotype, as well as on the living and dead world surrounding them. Factors of evolution. According to Darwin, three main factors determine the evolution of organic life: variability, heredity, and natural selection. A new species cannot arise from nothing. It is the result of the spontaneous transformation, change of an old species. The basis of evolution lies in variability. But this is not enough. For evolution to be possible, it is necessary that the changed traits be hereditary; otherwise, these traits will disappear along with the death of the individual in which they arose, leaving no trace in the offspring. Therefore, for evolution, what is important is not variability in general, but hereditary variability. But even this does not yet represent an evolutionary process. In the evolutionary process, the quality of variability plays a huge role. Evolution presupposes more or less purposeful hereditary variability, giving the organism greater adaptability to the environment. But since the variability of an organism's structure is not always beneficial to its possessor, it is obvious that in nature there must exist some third factor that eliminates harmful and useless changes arising in organisms, leaving only forms possessing more or less useful traits. This third factor was named by Darwin natural selection. The problem of variability in its full breadth after Darwin was first posed by Weismann, and then by Johannsen. Weismann was the first to clearly distinguish between the concepts of hereditary and non-hereditary variability, while Johannsen, with his doctrine of pure lines, raised evolutionary theory to a higher level. Johannsen was the first to point out the fundamental difference between the external manifestation of traits in an organism and the hereditary predispositions of these traits. Two organisms may differ in their hereditary structure (genotype), but this difference may not be externally apparent (phenotypically). We encounter this phenomenon constantly when we study, on the one hand, heterozygous and, on the other, homozygous forms with respect to the same trait. For example, the eye color of the fruit fly (Drosophila melanogaster) is inherited as red color.

red color ' white color- ^{and M}U^CH structure ^^^^ phenotypically will be the same. On the other hand, we can have organisms that are completely identical in their hereditary predispositions, but at the same time externally different. Thus, under the influence of light, cacti change their flat shoots into cylindrical ones. The water beetle in water gives different lateral shoots than on land. Canaries fed with hemp seeds have dark feather coloring, while those fed with cayenne pepper are colored; in red color. In all these examples, the number of which could be increased many times over, the hereditary structure of the organisms remains the same, despite the fact that the phenotype changes. All this shows that one cannot judge the hereditary structure of a trait by its external manifestation. One must strictly distinguish between non-hereditary changes in the body (soma), the so-called somations, from hereditary variability, which is always necessarily associated with changes in the chromosomal apparatus. Hereditary changes in the chromosomal apparatus arise in various ways. New, more or less hereditarily stable forms can be obtained by crossing organisms of different hereditary structure. Thus, by crossing cold-resistant wheat, but with low grain quality, with non-cold-resistant wheat, but with high grain quality, one can obtain a certain number of forms that possess both cold resistance and high grain quality. Interspecific crossings can also give new stable hereditary forms. In this respect, the hybrids obtained by G. D. Karpechenko from crossing cabbage (Brassica oleracea) with radish (Raphanus sativus) are of extraordinary interest. In animals, however, this path of formation, as shown by Federley in 1928, hardly plays any significant role. A major role in the process of speciation is played by mutations (see), i.e., changes in individual sections of chromosomes or changes in the number of chromosomes. Changes in individual sections can occur either due to the inactivation or loss of part of the chromosome (deficiency), or the transplantation of some part from one chromosome to another or from one end to the other end of the same chromosome (translocation), or the physicochemical change of the genes themselves. In the study of hereditary variability, the school of T. G. Morgan has achieved particular success with its work on the fruit fly, the school of Blakesley with Jimson weed (Datura), the school of Bauer with snapdragon (Antirrhinum), and others. All these phenomena, revealing the internal mechanisms of the process of formation, do not answer the question: what forces set these mechanisms in motion, what, in Darwin's expression, serves as the match that explodes the powder keg? An answer to this question was only obtained in 1927 thanks to the well-known works of Müller on the X-ray irradiation of Drosophila. Müller managed to prove that the direct impulse to formation in Drosophila can be the effect of X-rays on them. These experiments were repeated by many researchers, in particular in our USSR by a group of geneticists led by A. S. Serebrovsky, and the results were the same. Blakesley and others tested them on botanical material. The verification gave positive results. Thus, the possibility of artificially obtaining mutations was discovered, which significantly facilitated the study of questions of hereditary variability. In economic practice, mutations have long been used as material for the formation of new breeds. The method by which new forms are developed is artificial selection. C. Darwin studied this method in detail, paying special attention to its creative significance. A comparative analysis of domestic animals and cultivated plants with wild forms led him to the thought that such selection occurs spontaneously in nature itself and that only this process leads to the change of organic forms. Instead of the conscious, purposeful activity of man selecting forms useful to him, in nature there takes place the struggle for existence (see), which spontaneously leads to the selection of the most adapted organisms. The less adapted cannot withstand the struggle and in the overwhelming majority of cases perish without leaving any offspring. Only the most adapted can leave offspring, to whom they will transmit by inheritance those traits that led them to victory. The same processes of struggle and selection will also occur in new generations, which leads to a continuous evolutionary process, to a constant change of organic forms, to their better adaptability to the environment. This, of course, does not mean that some ancient ichthyosaur or later mammoth were less adapted to the conditions of their habitat than some modern animal to its modern environment. This should mean that in the changed conditions the old forms proved less adapted than the new ones and had to give way to them on earth. To improve breeds of livestock and cultivated plants, man consciously preserves the useful, isolating or destroying the harmful. The same processes occur in nature on a larger scale. But these processes do not depend on any will, have no predetermined goal, they are blind and spontaneous. Opponents of D. often point out that the theory of natural selection is a "vacuous, unverified speculation". To these objections, the following answer must be given. If we did not know a single concrete example of natural selection, this fact would in no way diminish the significance of the theory, which is a logical conclusion from other concrete facts. No one has ever seen and will ever see the process of transformation of our ape-like ancestor into man, nevertheless the fact of this transformation, to which we come by purely logical means, is for us no less, if not more, convincing than many facts that can be seen with the eyes or felt with the hands. But even if we discard this conclusion, the above objections to the theory of natural selection do not withstand criticism from the factual side. We know extremely many examples of the struggle for existence and the survival of the most adapted in natural conditions. Many of these facts were already known to Darwin, others became known after him. Let us cite a few of them. In 1727, a pack of brown rats swam across the Volga near Astrakhan and headed west. From this moment on, a stubborn struggle began everywhere throughout Europe between brown rats and local black long-tailed domestic rats. The stronger, voracious brown rat won a complete victory over the rats, displacing them everywhere. At present, the domestic black rat is a great rarity in Germany. The honey bee, brought from Europe to Australia and equipped with a sting, has completely displaced the local bee, deprived of this organ of defense and attack. Tower (1910) distributed various species of Colorado beetle (Leptinotarsa) in various localities in Mexico and after a certain time studied their numerical ratio. It turned out that in different localities and under different conditions, different species survived. Chesnola (1904), and then Belyaev (1926), investigated the significance of protective coloration in insects - praying mantises (Mantis religiosa). The first tied brown mantises partly to green plants, partly to brown ones. He did the same with green mantises. Mantises sitting on plants of the same color as them survived much better. Belyaev obtained analogous results for three varieties of mantises - yellow, brown, and green, planted on brown soil. These few facts, taken at random, are sufficient to show on what rich factual material Darwin's theory of natural selection is based. Opponents of Darwinism often point out that "selection is incapable of creating anything new; at best it can only preserve what is given in advance." And from this they conclude about the complete powerlessness of selection. First of all, it should be pointed out that if selection only preserved the useful and discarded the harmful, its creative role would be enormous. But selection not only preserves and weeds out what is already given in ready form in nature, it influences the entire path, the entire direction of the evolutionary process. Natural selection is the sole supplier of material for variability. And it is by no means indifferent to the evolutionary process what material will change. If, for example, natural selection on the continent will destroy wingless insects, while on islands only wingless or individuals with underdeveloped wings will survive, then obviously the further evolution of the first and second groups of insects will be different. Against the theory of natural selection, the objection is also raised, stating that "selection creates nothing new; it only preserves the norm, discarding extreme deviations and thus being a conservative, not a revolutionary factor." We have already seen that the reasoning about the conservative role of selection does not withstand criticism. As for the norm, the latter in the organic world is considered the average type, best adapted to the given conditions and therefore most frequently encountered.

Thus, the norm itself is a product of natural selection and remains within certain limits until the external conditions change. A change in the conditions of existence can also cause a change in the norm. For example, Weismann made the following interesting observation on seasonal dimorphism in some plants growing on mountain meadows. Some species of gentian and eyebright have two forms. One flowers before the haymaking, the other after it. Related species growing where there is no haymaking occur in a single form, flowering at the usual time. Undoubtedly, the intervention of man, who carries out haymaking, has split these monomorphic forms into dimorphic ones. Natural selection occurred, on the one hand, of individuals differing in early flowering, and on the other hand, of individuals flowering late. The intermediate form—the norm—was destroyed. As a result, two new races, two new norms, adapted to haymaking, were developed. Further development of D. Major stages in the evolution of the evolutionary theory proposed by Darwin should be considered the moments associated with the names of A. Weismann, Johannsen, Mendel, Morgan, and Müller. In addition, Huxley in England, Haeckel in Germany, K. A. Timiryazev in our country should be noted not only as major followers and 'apostles' of D., but also as scientists who undoubtedly deepened Darwin's theory, each in his own special field. Weismann, with his doctrine of the continuity of germ plasm, as well as the precise formulation of the problem of the inheritance of acquired characteristics, caused a critical attitude toward unverified and often simply incorrect facts accepted by evolutionary theory on faith. He was the first to show that the question of the inheritance of acquired characteristics, which seemed to him 'self-evident,' is not as simple and clear as it seemed before, either from a practical or theoretical point of view. Moreover, he questioned the positive solution to this problem and, after thorough analysis, came to its complete negation. Weismann several times modified his point of view, but its main core remained invariably the same: acquired characteristics are not inherited. The facts on which Weismann could rely at that time were rather scarce, and all his reasoning bears the imprint of some speculation and is not devoid of erroneous conclusions. But the main idea of his about the incorrectness of the doctrine of the adequate inheritance of acquired characteristics, as further research, especially genetic research of our time, showed, was undoubtedly correct. All facts that were previously described as cases of adequate inheritance of acquired properties, with new, more precise research methods (genetic analysis), do not agree with what was written about them, and not only do not confirm this point of view, but often refute it. Weismann, initially denying any dependence of changes in hereditary substance on changes in the body, at the end of his life admitted the possibility of the simultaneous parallel influence of external conditions on somatic and germ cells (parallel induction), while still refusing to recognize the direct adequate influence of changes in the soma on the hereditary substance (somatic induction). The denial of both parallel and somatic induction of course does not mean a refusal to recognize the influence of the external environment on the organism. The external environment undoubtedly influences the hereditary variability (see) of the organism. No one other than one of the most orthodox and outstanding modern geneticists, Müller, experimentally proved this influence. A critical attitude toward the question of recognizing the inheritance of acquired characteristics means and can only mean a refusal from the mystical demands of the Lamarckists to recognize the adequate influence of changes in the soma on the hereditary substance. It seems completely incomprehensible, for example, why the increase of any muscle should affect the hereditary material precisely at the point where the determinants determining the development of this muscle are located, and precisely in the direction of its exact increase, not decrease, without affecting the other hereditary determinants at all. De Vries' mutation theory had the following significance for the further development of evolutionary theory: it focused attention on mutation variability in general, although De Vries' own reasoning about the causes of this variability turned out to be incorrect. 1900 was a turning point in the history of evolutionary teaching. In this year, three botanists (De Vries, Correns, and Tschermak) rediscovered the laws of Mendel, published by him as early as 1865, but which had lain dormant for 35 years. From this new discovery of the basic laws of heredity, evolutionary theory rises to a higher level. A major stage in the development of evolutionary teaching is the work of Johannsen on pure lines, variation statistics, phenotype and genotype. Johannsen was the first to show the hereditary heterogeneity of populations. When studying heredity, one must start not from populations, but from pure lines. Only in a pure line does Darwinian selection play a role. It has no significance for populations. As for variation statistics, Johannsen first of all cleansed it from the soulless formalism with which it suffered since the time of Quételet, Pearson, etc. He showed that variation statistics in biology can have significance as a research method only in the presence of a proper genetic analysis. A formal mathematical approach to biological phenomena not only brings no benefit, but often gives simply incorrect results. When applying the variation-statistical method, one should remember that the hereditary content of an organism (genotype) is not the same as its external manifestation (phenotype). Phenotypically homogeneous material is not yet genotypically homogeneous. Therefore, in statistical analysis, one cannot lump everything together, but it is necessary to first carry out a thorough genetic analysis of the material under study. Only in this case can variation statistics play the role of a useful research method in biology. Johannsen's merit also lies in the careful distinction between the concepts of phenotype and genotype and the extremely subtle analysis of many biological concepts in general and their cleansing from everything metaphysical, superimposed. Genetics received particularly strong development thanks to the American school led by T. H. Morgan. Questions of heredity in Darwin's time were not completely worked out, and no scientific analysis of these problems could be spoken of in his time. Meanwhile, they play a cardinal role in any theory of evolution. Darwin himself could not do without a theory of heredity and was forced to deal with this problem. The result of these studies was his unsuccessful theory of pangenesis, from which he himself very soon abandoned. The lack of a scientifically based theory of heredity forced one to accept heredity as a fact, without any analysis of it, which often led evolutionary theory to incorrect conclusions. A bright example of this can be the semi-Lamarckian tendencies in the teaching of Darwin himself, for example, his assertions about the hereditary fixation of the results of exercise and non-exercise. Modern genetics has enriched evolutionary teaching with a deep development of the problems of hereditary variability, freed it from the scholastic speculations of the end of the last century, and gave it a solid scientific foundation. In addition, it developed the problems of the genotypic structure of populations, established the regularities of development of these populations in connection with their genotypic structure (Hardy, Chetverikov, etc.), and raised new problems that have major significance for the evolutionary process. Such is, for example, the problem of genogeography (A. S. Serebrovsky). In the very recent past, genetics has closely approached the question of the structure and nature of the gene (Demerec, the school of A. S. Serebrovsky, etc.). The resolution of this most cardinal question of modern teaching on heredity, one way or another, cannot remain indifferent to D., since the evolution of species is the evolution of genotypes, which is largely determined by the nature of these very genotypes. In 1927, thanks to the work of Müller, genetics finally achieved a positive resolution of the question of the artificial production of mutations. The relatively easy production of mutations in laboratory conditions by means of Müller's technique has significantly facilitated the task of studying the mechanisms of heredity, and thereby the mechanisms of the evolutionary process. Methodology of D. The idea of the continuous variability of the organic world, as has already been indicated, is lost in the deep past; it does not disappear in the Middle Ages either. Nevertheless, the doctrine of evolution belongs to the age of Hegel, Marx, Engels, and Darwin. Previously, they spoke of variability, of periodic cycles rotating in an unchanging circle, of a single origin. In these representations there was mechanical becoming, but not progressive development, there was no evolution with its irreversible new formations. According to Empedocles, for example, the organic world is not a product of development, organisms arose suddenly in a finished form, as a result of the mechanical spontaneous connection of separately grown organs.

The mechanistic concept, which reduces the abundance of forms in the inorganic and organic world to various quantitative combinations of eternally unchanging particles, is also not an evolutionary viewpoint, since here too the main moment of evolution, the moment of new formation, is overlooked. From a mechanistic standpoint, unwilling to see qualitative distinctions in the objective world, all evolution must inevitably be reduced to simple mechanical displacement or quantitative change in the constituent parts of developing objects. The same, essentially mechanistic viewpoint is developed at the present time by the Dutch botanist Lotsy, when, denying processes of new formation, he attempts to explain the entire evolutionary process solely by combinations of eternally unchanging genes. The evolutionary process, understood dialectically, is above all a creative process. In its development, matter not only changes the location and number of its constituent parts but also qualitatively changes the form of its existence. The process of evolution consists in the dialectical transformation of one quality of the developing substrate into another. What was before changes, but in the process of change arises what was not before, that is, something new arises, not the repetition of the old. And here we approach the question of the continuum (continuity) and discreteness (discontinuity) in the evolutionary process. The process of evolution is both discontinuous and at the same time continuous. It is discontinuous, since it consists of processes of new formation, processes of qualitative change of old material. It is at the same time continuous, since each form is not created from nothing, but is a historical continuation of the old form, its modification, not an absolute negation. The mechanistic viewpoint, since it does not see new formation in the evolutionary process, must inevitably deny this unity of discontinuity and continuity of evolutionary processes and proclaim only continuous processes. The mechanistic concept does not know the problem of the 'jump', it simply denies it. Another extremely important problem of evolution is the problem of chance. Changes in organic forms, according to Darwin, can occur in any direction. Natural selection deals with random changes. This idea of Darwin about the random character of adaptations causes particularly strong objections. Emphasizing the unacceptability for himself of the Darwinian concept as a 'theory of chance', the greatest contemporary vitalist Driesch characterizes Darwinism as a 'theory that builds houses by throwing stones'. These arguments would have some meaning with respect to a theory that tried to prove the emergence of the ready-made modern world of living beings by the one-time random conjunction of atoms and molecules. But such an absurd conception of evolution was held not only by Darwin but even by his predecessors. One cannot oppose chance to regularity, as Driesch, Berg, Pauli, and others do. The proclamation of the universal reign of regularity and the declaration of chance as a subjective category contains nothing but an empty phrase. F. Engels on this matter expresses himself as follows: 'That there are five peas in this pod and not four or six, that the tail of this dog is five inches long and not longer or shorter by one line, that this clover flower was fertilized this year by a bee and that one not, and moreover by this particular bee and at this particular time, that this particular, wind-blown seed of the lion's mouth sprouted and others did not... all these facts are caused by the unchanging connection of causes and effects, are linked by immutable necessity, and the gas ball from which the solar system arose was so constituted that these events could only have happened thus and not otherwise. With this kind of necessity we still do not go beyond the bounds of the theological view of nature. For science it is completely indifferent whether we call this, together with Augustine and Calvin, the eternal decree of God, or together with the Turks, Kismet, or whether we call it necessity. In none of these cases can there be talk of studying the chain of causes, in none of these cases do we make any progress. The so-called necessity remains a simple phrase, and thanks to this chance remains what it was.' Chance has just as objective a significance as necessity. For an individual animal or plant it is chance where it was born and what environment it finds around itself. Even if we know the reasons that led to this animal or plant being born precisely in this place and not another, this event will still remain a chance, since the probability of events depends only on conditions, not on the degree of our knowledge. We call a phenomenon random if it arose as a result of the intersection of two or more independent causal series. From the properties of each of these series it by no means follows that these series had to intersect precisely at this point or at all to intersect. A concrete example will clarify this idea. Suppose that in a given area for some reason the climate became drier. From this fact it by no means follows that under these conditions individuals must necessarily appear that can be satisfied with less moisture. But such individuals may appear, and this objective but random coincidence can lead to the formation of a new species. The random character of this coincidence cannot be changed by whether we know or do not know the reasons that determined this coincidence. The opposition of chance and causality inevitably leads to the recognition of some causeless chance, which is an obvious absurdity. Connected with the problem of selection is another extremely important problem - the problem of purposiveness. Markov in a letter to Lassal points out that Darwinism is a 'rational explanation of natural purposiveness.' Any evolutionary theory is essentially an attempt to give a rational explanation of these phenomena of purposiveness. Our viewpoint on purposiveness will depend on which evolutionary theory we accept. If we take the standpoint of Berg, we will have one explanation ('original purposiveness'), if we accept the views of Driesch, we will have another explanation ('entelechy'), the standpoint of Lamarck will give a third explanation ('internal striving caused by changed needs'), Darwinism a fourth ('natural selection') and so on. Which of all the existing modern theories explaining organic purposiveness is from the Marxist standpoint the most acceptable? First of all it is necessary to emphasize that from the standpoint of Marxism no thing, no organ is in itself either purposive or non-purposive. The butterfly's proboscis is useful to it when it is adapted to a certain structure of the nectar-bearing parts of a flower. The discrepancy between the structure of the proboscis and the flower makes the proboscis useless or even harmful to the butterfly, since under such conditions the butterfly is deprived of its main instrument for obtaining food. The proboscis becomes purposive, useless, or harmful only under certain conditions, in certain relations. From this it follows that the problem of purposiveness is above all a problem of relation, and from this standpoint it must be resolved. Vitalists introduce into the organic world immanent purposiveness. They consider purposiveness not as a result of adaptation, but as a result of a basic elementary property inherent in any organism. By this they give this purposiveness absolute value. This elementary property has different names among different vitalists (entelechy, life force, system of impulses, dominance, etc.). Just as the basic properties of matter (motion, etc.) are inseparable from it and serve as the basis from which develop the concrete forms of existence of matter, so, in the opinion of vitalists, immanent purposiveness is inseparable from the living organism and serves as sufficient basis for its concrete reactions and adaptations. Vitalists believe that in the study of purposiveness of organic forms we must proceed from this elementary, indecomposable property of living matter, about the origin of which we can say nothing, just as we can say nothing about the origin of motion, gravity, and other elementary properties of matter. With such a helpless viewpoint Marxism obviously has nothing to do. Purposiveness is a fact, but not an explanation of the fact. The mechanistic viewpoint seeks an explanation of purposiveness in the physico-chemical structure of the organism. According to mechanists, purposiveness is an expression of the physico-chemical processes occurring in the organism, therefore, they think, we must seek its explanation in the physics and chemistry of the organism. Thus for mechanists the problem of purposiveness is not a problem of relation, but a problem of structure, of organization. Such a formulation obviously confuses two different problems: the problem of the organization of living beings with the problem of the relation of this organization to the surrounding conditions.

In seeking to answer the question of what forces lead to the purposeful organization of the organic world, mechanists in fact leave this question aside and attempt to answer a completely different question, namely, what constituent elements make up a given organic system, without any relation to its purposefulness or lack thereof. From a principled standpoint, the same physicochemical processes lead to the organization of the human stomach and appendix, yet in the first case we undoubtedly have a purposeful organ, while in the second a useless and even harmful one. Darwin 'rehabilitated' organic purposefulness, discredited by teleology. He revealed its relative and regulative character and gave it a completely correct rational explanation. Only Darwin's theory of natural selection provides the only correct dialectical-materialist explanation for the emergence of purposeful adaptations and reactions in the organic world. At present, we know of no other scientific explanation for these phenomena. Any diminution of the importance of selection in this regard, as is done by Lamarckians at least, is a rejection of materialism in favor of idealism. Darwinism has played an enormous role in the history of methodology and worldview. All of science in the second half of the 19th century proceeded under the sign of Darwinism. But nowhere did its influence reflect itself as strongly as in biology. All branches of biological knowledge were restructured from the point of view of Darwinism, which quite deservedly became the methodology of biology. In this respect, it is a concrete manifestation of the methodology of dialectical materialism in the field of biology. The role of Darwinism in biology is extremely similar to the role played by historical materialism in sociology. This role of Darwinism is aptly expressed by F. Engels. In his eulogy at Marx's grave, Engels said: 'Just as Darwin discovered the law of development of organic nature, so Marx discovered the law of development of human history.' With these words, Engels emphasizes not only the great significance of Marx's theory, but also the enormous significance of Darwinism as the methodology of biology. Recognition of Darwinism as the methodology of biology does not yet mean recognition of Darwinism as a universal methodology suitable for all areas of our knowledge, as the so-called social Darwinism insists. Attempts to transform Darwinism into an all-encompassing methodology date back to Darwin himself, who more than once tried to use the biological method he discovered not only for the investigation of biological questions, but also for providing a 'natural-scientific foundation for the capitalist system of domination.' We encounter similar aspirations in Haeckel and many other Darwinists of the 19th century and our time (Plate and others). To what such a universalization of the methodology of a particular science leads is shown by the most vulgar reasoning of the great Darwin on sociological topics. 'The inheritance of property,' writes Darwin in his book 'The Descent of Man and Selection in Relation to Sex,' 'in itself by no means constitutes an evil; indeed, without the accumulation of capital, the arts could not have progressed, and it is they that have mainly allowed the civilized races to spread and now continue to spread everywhere, displacing the lower tribes.' In another place in the same book, Darwin gives the following 'scientific' explanation for the concentration of capital and competition among the bourgeoisie. 'Without doubt,' he writes, 'wealth, if it is very great, tends to turn people into useless drones, but the number of such members of society is never very large: moreover, here occurs a kind of spontaneous elimination, since we daily see that those rich men who turn out to be foolish or extravagant squander all their fortune.' These limited bourgeois commonplace remarks of Darwin to a large extent grow out of Darwin's desire to apply his methodology to sociological investigations as well. The universality of Darwinism required searching for 'natural selection' everywhere, and Darwin looks for it even where it does not and did not exist. According to Darwin, morally less-endowed capitalists, by virtue of the natural conditions of the struggle for existence, must yield their place to morally more steadfast representatives of this class. Extravagance is declared the most important factor in capitalist elimination, i.e., ruin. The mechanical transfer of laws from one type of phenomenon to another and the failure to take into account the specific uniqueness of each stage in the development of the material world devalues even the best methodology of a particular science, such as Darwinism in biology. But of course, the use of Darwinism for sociological conclusions that do not follow from it at all will cease only when class society and the associated struggle of ideologies disappear. (See also Biogenetic law, Struggle for existence, Weismann's theory, Genetics, Natural selection, Variability, Lamarckism, Mutation, Heredity, Neo-Darwinism, Evolutionary theories). 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Ravich-Cherkaesky, Kharkov, 1923; De Lai J. and Goldsmith M., Theories of evolution, P., 1916; Judd D., The origin and development of the idea of evolution, M.-L., 1924; Zavadovsky B., Darwinism and Marxism, M.-L., 1926; Ivanzov N., Factors of evolution, M.-L., 1923; he also, Darwinism and Mendelism, Vologda, 1926; Kozho-Polyansky V., The last word of anti-Darwinism, Krasnodar, 1923; he also, New principle of biology, L.-Zh., 1924; he also, Dialectics and biology, Rostov n/D-Krasnodar, 1925; he also, Darwinism-scheme, Vologda, 1925; Korshikov A., Evolutionary theory in historical exposition, Kharkov, 1924; Lamarck J., Philosophy of zoology, M., 1911; Menzbir M., For Darwin, M.-L., 1927; Morgan T., Theory of evolution in modern light, M.-L., 1926; Morgan T. and Philipchenko Y., Are acquired characteristics inherited, L., 1925; Nekrasov A., Struggle for Darwinism, M.-L., 1926; he also, Sexual selection and secondary sexual characteristics, Moscow-Leningrad, 1927; Plate L., Evolutionary theory, M.-L., 1928; Polyakov I., Modern evolutionary theory, Kharkov, 1928; Origin of animals and plants, coll. ed. by S. 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