The idea of organisms changing over time is first found in the pre-Socratic Greek philosophers. The representative of the Milesian school, Anaximander, believed that all animals originated from water, after which they came to land. Man, according to his ideas, originated in the body of a fish. Empedocles has ideas of homology and survival of the fittest. Democritus believed that land animals descended from amphibians, and those, in turn, spontaneously generated in silt. In contrast to these materialistic views, Aristotle considered all natural things to be imperfect manifestations of various permanent natural possibilities, known as "forms", "ideas" or (in Latin transcription) "species" (lat. species) . However, Aristotle did not postulate that the real types of animals are exact copies of metaphysical forms, and gave examples of how new forms of living beings can form.
In the 17th century there appeared new method, who rejected the Aristotelian approach and sought an explanation of natural phenomena in the laws of nature, which are the same for all visible things and do not need immutable natural types or a divine cosmic order. But this new approach hardly penetrated the biological sciences, which became the last stronghold of the concept of an invariable natural type. John Ray used a more general term for animals and plants to define unchanging natural types - “species” (lat. species), but, unlike Aristotle, he strictly defined each type of living being as a species and believed that each species could be defined traits that are reproduced from generation to generation. According to Ray, these species are created by God, but can be changed depending on local conditions. Linnaeus's biological classification also considered species to be immutable and created according to a divine plan.
However, at that time there were also naturalists who were thinking about the evolutionary change of organisms that occurs over a long time. Maupertuis wrote in 1751 about the natural modifications that occur during reproduction, accumulate over many generations and lead to the formation of new species. Buffon suggested that species could degenerate and change into other organisms. Erasmus Darwin believed that all warm-blooded organisms possibly originated from a single microorganism (or "filament"). The first full-fledged evolutionary concept was proposed by Jean-Baptiste Lamarck in 1809 in his work "Philosophy of Zoology". Lamarck believed that simple organisms (ciliates and worms) are constantly spontaneously generated. Then these forms change and complicate their structure, adapting to the environment. These adaptations are due to the direct influence environment through the exercise or non-exercise of organs and the subsequent transmission of these acquired characteristics to descendants (later this theory was called Lamarckism). These ideas were rejected by naturalists because they had no experimental evidence. In addition, the positions of scientists were still strong, who believed that species are immutable, and their similarity indicates a divine plan. One of the most famous among them was Georges Cuvier.
The end of the dominance in biology of ideas about the immutability of species was the theory of evolution through natural selection, formulated by Charles Darwin. Influenced in part by Thomas Malthus's The Essay on Population, Darwin observed that population growth leads to a "struggle for existence" in which organisms with favorable traits begin to predominate, as those that lack them perish. This process begins if each generation produces more offspring than it can survive, leading to competition for limited resources. This could explain the origin of living beings from a common ancestor due to the laws of nature. Darwin developed his theory from 1838 until Alfred Wallace sent him a paper with similar ideas in 1858. Wallace's paper was published that same year in one volume of the Proceedings of the Linnean Society, along with a brief excerpt from the Works of Darwin. The publication in late 1859 of Darwin's On the Origin of Species, which explains the concept of natural selection in detail, led to the wider dissemination of Darwin's concept of evolution.
Since then, the modern synthesis has been expanded to explain biological phenomena at all levels of living organization and stages of individual development. The latter was the prerequisite for the emergence of the Evo-Devo concept.
Criticism of evolutionism[ | ]
Criticism of evolutionism appeared just after evolutionary ideas emerged in the early nineteenth century. These ideas were that the development of society and nature is governed by natural laws, which became known to the educated public from the book by George Combe (English)Russian The Constitution of Man () and the anonymous Vestiges of the Natural History of Creation (). After Charles Darwin published The Origin of Species, most of The scientific community agreed that evolution is a fact because Darwin's theory is based on empirical evidence. In the 1930s and 1940s, scientists developed the synthetic theory of evolution (STE), which combined the idea of Darwinian natural selection with the laws of heredity and population genetics. Since that time, the existence of evolutionary processes and the ability of modern evolutionary theories to explain why and how these processes occur has been supported by the vast majority of biologists. Since the advent of STE, almost all criticism of evolutionism has been made by religious leaders (mainly Protestants), not by scientists.
Evolutionism and religion[ | ]
It should be noted that the accusations of atheism and the denial of religion, cited by some opponents of evolutionary doctrine, are based to a certain extent on a misunderstanding of the nature of scientific knowledge: in science, no theory, including the theory of biological evolution, can either confirm or deny the existence of such otherworldly subjects, like God (if only because God, when creating living nature, could use evolution, as the theological doctrine of “theistic evolutionism” claims).
Efforts to oppose evolutionary biology to religious anthropology are also mistaken. From the point of view of the methodology of science, the popular thesis "man descended from apes" is just an oversimplification (see reductionism) of one of the conclusions of evolutionary biology (about the place of man as a biological species on the phylogenetic tree of living nature), if only because the concept of "man" is ambiguous: man as a subject of physical anthropology is by no means identical to man as a subject of philosophical anthropology, and it is incorrect to reduce philosophical anthropology to physical one.
Some believers of different religions do not find evolutionary teachings contrary to their faith. The theory of biological evolution (along with many other sciences - from astrophysics to geology and radiochemistry) contradicts only the literal reading of the sacred texts that tell about the creation of the world, and for some believers this is the reason for rejecting almost all the conclusions of the natural sciences that study the past of the material world (literalist creationism ).
Among believers who profess the doctrine of literal creationism, there are a number of people who are trying to find scientific evidence for their doctrine (so-called "scientific creationism"). The scientific community recognizes such evidence as untrue, and the directions themselves as pseudoscientific.
Recognition of evolution by the Catholic Church[ | ]
see also [ | ]
Notes [ | ]
- Kutschera U., Niklas K. J. The modern theory of biological evolution: an expanded synthesis // Naturwissenschaften. - 2004. - Vol. 91, no. 6. - P. 255-276.
- , from. 118-119.
- , from. 124-125.
- , from. 127.
- Torrey H. B., Felin F. Was Aristotle an evolutionist? // The Quarterly Review of Biology. - 1937. - Vol. 12, no. 1. - P. 1-18.
- Hull D.L. The metaphysics of evolution // The British Journal for the History of Science. - 1967. - Vol. 3, no. 4. - P. 309-337.
- Stephen F Mason. . A history of the sciences. - Collier Books, 1968. - 638 p.- P. 44-45.
- , from. 171-172.
- Ernst Mayr. . The growth of biological thought: diversity, evolution, and inheritance. - Harvard University Press, 1982. - ISBN 0674364465.- P. 256-257.
- Carl Linnaeus (1707-1778) (indefinite) (unavailable link) Archived from the original on April 30, 2011.
- , from. 181-183.
- , p. 71-72.
- Erasmus Darwin (1731-1802) (indefinite) (unavailable link). // University of California Museum of Paleontology. Date of treatment February 29, 2012. Archived from the original on January 19, 2012.
- , from. 201-209.
- , p. 170-189.
- , from. 210-217.
- , p. 145-146.
- , p. 165.
- , from. 278-279.
- , from. 282-283.
- , from. 283.
- Stamhuis I. H., Meijer O. G., Zevenhuizen E. J.// Isis. - 1999. - Vol. 90, no. 2. - P. 238-267.
- , from. 405-407.
- Dobzhansky T. Nothing in biology makes sense except in the light of evolution // The American Biology Teacher. - 1973. - Vol. 35, no. 3. - P. 125-129.
- Avise J. C., Ayala F. J. In the Light of Evolution IV. The Human Condition (introduction) // Proceedings of the National Academy of Sciences USA. - 2010. - Vol. 107. - P. 8897-8901.
- Johnston, Ian C. …And Still We Evolve. Section Three: The Origins of Evolutionary Theory (indefinite) . // Liberal Studies Department, Malaspina University College (1999). Retrieved April 30, 2010. Archived from the original on September 27, 2006.
- IAP Statement on the Teaching of Evolution Archived September 27, 2007 at the Wayback Machine, Interacademy Panel.
- In a detailed work on creationism, The Creationists (English)Russian» Historian Ronald Numbers has traced the religious motivations and attempts at scientific analysis of well-known creationists to George Frederick Wright. (English)
evolutionary doctrine- This is a branch of biology that studies the general patterns and driving forces of the historical development of the organic world.
There are two views on the origin of life:
ü idealism(from the Greek idea - idea) - a doctrine that claims that the primary is the spirit, consciousness, and all physical bodies and nature are secondary.
ü materialism(materialis - material) - the world is material and exists independently of consciousness.
Idealistic views in biology are called − creationism(from the Latin creator - the creator). Materialism claims that all organisms originated naturally, and their adaptations to the environment are the result of a long biological evolution.
Evolution- the development over time of complex organisms from previous simpler ones.
biological evolution(from Lat evolution - unfold) - is called the process of historical development of wildlife from the appearance of life on Earth to the present day.
The term "evolution" was first used by the Swiss naturalist Charles Bonnet in 1762
Biological evolution is an irreversible non-directional process, i.e., although the general line of development of life on Earth is to complicate the organization, the adaptability of living organisms to environmental conditions can be achieved in different ways, including the acquisition of particular adaptations and simplification of their structure.
Evolution result:
ü Variety of species;
ü The emergence of devices (adaptations);
ü Complication of the organization of living beings (progressive nature of evolution);
ü Changing communities of organisms (biocenoses);
ü The emergence of the biosphere;
ü Emergence of prerequisites for human development.
The study of the general laws and driving forces of the historical development of living nature is the subject of evolutionary teaching.
The main stages of evolutionary teaching
(history of evolutionary ideas).
pre-Darwinian period.
Ancient China.
Confucius- life arose from one source, by gradual deployment and branching.
Ancient era.
Diogenes- all beings are the result of differentiation of one and the same being and are similar to it.
Empedocles- air, earth, fire, water, four roots of all things. Life arose as a result of the forces of attraction and repulsion of these four elements.
Democritus- living beings arose on earth from silt by spontaneous generation.
Anaxagoras Organisms arose from embryos that floated in the air.
Thales(640-546 AD) - all life came from water.
Anaximander- Animals and man arose from the mud on the forming Earth.
Aristotle(384-322 AD) - formed the theory of the continuous and gradual development of the living from inanimate matter.
Middle Ages ( 400-1400 AD). Theories are based on earlier concepts, or recognition of creationism.
Renaissance. Feudalism and early capitalism(dominance of the Christian church).
The rise of science and art, the time of the Great Discoveries: Vasco da Gama discovered sea route around Africa to India, Christopher Columbus discovered America, etc. As a result of trade and navigation, knowledge of the diversity of the organic world is growing.
John Ray(1627-1705) - created the concept of species. Applied the concepts of systematic units childbirth And species.
Carl Linnaeus(1707-1778) - created the "System of Nature" (1735) - in which he classified all natural bodies according to a hierarchical principle (the lower levels were part of the higher ones). He singled out 3 kingdoms: minerals, plants and animals. The classification has acquired the following form: kingdom, class, detachment, genus, species, variety.
Modern classification looks like this: superkingdom - kingdom - subkingdom - type (plant department) - class - order (plant order) - family - genus - species.
Linnaeus introduced the binomial (binary) system of nomenclature- the double name of the organism in Latin, where the first word meant genus, and the second species.
Felis leo - lion;
Felis tigris - tiger;
Felis domestica is a domestic cat.
Linnaeus placed man in the animal kingdom, the class of mammals and the detachment of primates.
Disadvantages of the theory of K. Linnaeus:
ü The artificiality of classification: it was based on arbitrarily taken signs, and not on the relationship of organisms. Example: according to the structure of the beak, he placed an ostrich and a chicken in one order.
ü Linnaeus professed a metaphysical approach: considering each species as the result of God's act of creation, he assumed the immutability of species.
Dawn of capitalism(18th-19th centuries).
Buffon(1707-1788) - expressed the opinion that different types of animals have different origins and arose in different time. He recognized the influence of the external environment and the inheritance of acquired traits. stood in position transformism- ideas about the variability of organisms under the influence of natural causes, leading to the transformation of some forms of plants and animals into others.
Later, many scientists developed views on the variability of species: Walter (1694-1778), P. Holbach (1723-1729), N. Rousseau (1712-1778)
D. Diderot (1713-1784) - small changes in all creatures and details of the time of existence on Earth can fully explain the emergence of various organisms of the world.
The ideas of the materialism of nature are contained in the works of scientists.
M.V. Lomonosov(1711-1765) - nature changes under the influence of natural factors, mountain-building processes, water, etc.
A.N. Radishchev(1749-1802) - described the presence in nature cycling linking together plants, animals and inanimate nature.
K. Wolf(1734-1794) - showed the gradual development of the embryo in the egg ( epigenesis theory), refuting preformism- the embryo is in the egg in an already formed form.
A. Kaverznev(1778) - the book "On the Rebirth of Animals".
Georges Cuvier(1769-1838) - founded science - comparative anatomy systematic unit; founded paleontology. He believed that the fossil remains are the results of "catastrophes", after which new species arose.
E. Geoffroy Saint-Hilaire(18th century) - the same facts that Cuvier used to confirm creationism, he considered as evidence of transformism; the unity of animal organisms is an indicator of the common origin; the presence of modern forms that differ from fossils, as proof of the variability of organisms under the influence of external and internal natural causes.
Jean-Baptiste Lamarck (1744-1829) – first evolutionary theory. Inheritance of acquired traits (the impact of the environment on the body and the transmission of phenotypic changes to descendants). The concept of exercise and non-exercise of organs.
Lamarck coined the term "biology"(from the Latin bios - life, Logos - science) and "biosphere" (from the Greek sfera - ball).
The main provisions of the evolutionary teachings of Lamarck.
ü Groups of organisms can be arranged according to the degree of complexity of their organization (gradation principle).
ü Species change over time, but are relatively constant.
ü The driving force of evolution (or the reason for the complication of organisms) is an internal desire for progress, inherent in organisms by nature (the Creator).
ü The environment has a direct (on plants and lower animals) and indirect (on higher animals through the nervous system) influence on the body, resulting in a variety of species within the step. When the environment changes, the habits of animals change, they begin to exercise more or not to exercise some organs, and these organs develop or, on the contrary, are lost.
o Example: in a mole, due to life underground, the reverse development of the eye (decreased); ducks, geese, frogs, sea turtles spread their fingers when swimming, and membranes formed between them. In snakes, due to the habit of crawling, the limbs disappeared, and the body became long and flexible, etc.
ü Favorable signs are inherited, i.e. modification variability is inherited.
Disadvantages of the theory:
ü Lamarck's worldview was based on deism- religious and philosophical doctrine, which considered the primary cause of the World - the Creator;
ü all the changes that occur with animals are directed, i.e. occur in the direction of the "necessary" animal. This is the main difference between Lamarck's teaching and the modern one (first, various changes are fixed and then, in the process of natural selection, the most necessary ones in given conditions are fixed);
Every individual is subject to change.
Ch. Darwin's teaching.
Charles Darwin(1809-1882) - formed the theory of evolution as a result of natural selection.
Prerequisites for the emergence of Darwinism.
I. Darwin's round-the-world voyage on the ship "Beagle" as a naturalist, which made it possible to collect extensive collections of valuable observations.
II. The achievements of selection testified that a person can change breeds and varieties, adapt them to his needs, through artificial selection, unconscious - they choose the best individual; or
methodical - in order to improve a property or feature.
III. Intensive development of natural sciences.
ü Comparative anatomy: establishing a general plan for the structure of large groups of animals (J. Cuvier, 1817)
ü Embryology: detection of the phenomenon recapitulation gill slits in the pharynx of chick embryos.
ü General biology: the creation of cell theories (T. Schwann, 1839).
ü Comparative anatomist and embryologist J. Saint-Hilaire and G. Owen developed the doctrine of homologous and similar organs.
ü Russian embryologist K.M. Baer opened law of germinal resemblance.
ü Geology: facts were obtained about the gradual change in the surface of the Earth (C. Lyell 1797-1875). Ch. Lyell's book is used by Darwin when creating his theory of evolution.
ü Chemistry: demonstrated the unity of the material basis of living and inanimate nature(F. Wöhler in 1828 synthesized urea, a product of biogenic origin).
IV. The German philosopher I. Kant and the French astronomer P. Laplace developed a hypothesis about the gradual formation solar system- The Sun, the Earth and all the planets - from a gaseous nebula under the influence of natural causes: the forces of rotation, attraction and repulsion.
V. Socio-economic background:
ü affirmation of English political economy(A. Smith, D. Ricardo) that competition is a "natural law" of social relations.
ü a treatise on overpopulation (1792) by T. Malthus, an English priest, on the need to reduce the population, which is ahead of food production.
- definite, directional, adaptive, or indefinite, non-directional and proving to be adaptive only by chance.
The first group of concepts and hypotheses is traditionally associated with the name of J. B. Lamarck. In 1809, he suggested that all living organisms expediently adapt to environmental conditions. So he explained one of the features of the organic world - adaptability. Progressive, the emergence of forms that are more complex and perfect, he explained by the "law of gradations" - the desire of living beings to complicate their structure. Once having arisen, adaptive changes further, according to Lamarck, are able to be inherited (the concept of "inheritance of acquired traits"). Thus arose a system of views on the evolutionary process, called Lamarckism. It is easy to see that Lamarck's concept does not explain anything. According to her, species evolve, adapting and becoming more complex, because they have such properties - to adapt and become more complex. Lamarckian views have adherents even today, although they do not always agree to be called Lamarckists. Different authors explain the reasons for directional changes differently, but they can be reduced to two: the directional influence of the external environment (for example, polar bear turned white with snow) or the ability of the organism itself.
Such hypotheses are called teleological (from the Greek words teleos - result and logos - teaching). The teleological view of the processes occurring in nature has a long history; it was first expressed by the ancient philosopher Aristotle. According to Aristotle, the cause of development is the future goal. So, according to Lamarck, the great adaptability of descendants arises as a result of purposeful ancestors.
Idealistic teleological teachings about violate the basic law of modern natural science - the law of causality, according to which the future cannot influence the present, just as the present cannot influence the past. Experimental verification of Lamarck's "laws" showed their inconsistency. Strictly speaking, it is enough to understand that Lamarck's system of views violates the law of causality, and there is no need for such experiments. Not building now perpetual motion machines to once again verify the correctness of the law of conservation of energy. According to Lamarckism, it is assumed that living organisms are able to find the right decision on how to improve themselves, and, moreover, are able to implement their own decision. Knowing how complex the body is, it is easy to understand that neither one nor the other is possible.
Lamarck's concept is powerless to explain the vast majority of evolutionary adaptations, for example, the kumaric shape of the eggs of the seabird guillemot that does not roll off the rock ledge, all the shapes and structures of flowers aimed at increasing the likelihood of pollination, the formation of the placenta and mammary glands in mammals, and much more. If accepted, then it must be assumed that nature has the gift of foresight for many generations to come.
But what about the directed one described in all living organisms, from to humans? For example, the ability to synthesize a special in response to the appearance of a substrate in the environment for this. So, in response to, the appearance of lactose in the environment of sugar appears - galactosidase, which breaks down this sugar. Summer tan in fair-skinned people appears in response to the action of the sun's rays. Directed is not a cause, but always the result of an evolutionary process. The ability to do it is the same adaptation that occurs over many generations. Therefore, it cannot be a proof of the correctness of Lamarckism; rather, on the contrary, it confirms its inconsistency. have a galactosidase acquired in DNA, as well as a mechanism that ensures that this is switched on when lactose appears in the environment. Human skin also already has the synthesis of black - melanin, and the rays of the sun only activate this process.
Another evolutionary doctrine, shared and developed now by the overwhelming majority of scientists, originates from the theory of Ch. (see). comes from an indefinite, non-directional, which does not need to be proved, it is visible to everyone who has ever observed several individuals of the same species (cows in a herd, puppies of the same litter, plants in the forest and on). This is unadaptable, it arises regardless of the environmental conditions faced by the ancestors or descendants will meet. We are well aware of the mechanism of this: it is occurring in DNA. Obviously, they cannot be adaptive, since the causes that cause them are in no way connected with what this one is responsible for. But sometimes some random changes turn out to be favorable for and in given specific conditions. Carriers of these changes are more likely to leave offspring and become winners in. and turns out to be the main driving force that gives it direction. This is how expediency and adaptability arise.
The further development of evolutionary doctrine is associated with the successes of genetics, and especially research. spoke only of the general category of the indefinite. Now it is divided into mutational (see) and combinational, or combinative. From the moment of division into these two categories, prerequisites arise for the creation of a new, synthetic theory. It is called so because it is a synthesis of classical genetics and theory. Its essence is as follows: newly formed changes, as well as combinations that appear as a result of the sexual process, are selected under the influence of environmental factors.
Much new data has also been obtained on selection. Now a distinction is made between individual selection of the fittest individuals, and family, group selection (selection of families of ants, bees, herds of ungulates, flocks of monkeys, etc.).
An important role is played by purely random processes occurring in small
evolutionary doctrine, theory of evolution - the science of causes, driving forces, mechanisms and general patterns evolution of living organisms.
The first stage of evolutionary teaching is associated with the activities of ancient philosophers (Heraclitus, Democritus, Lucretius, etc.), who expressed ideas about the variability of the surrounding world, including the historical transformations of organisms, about the unity of animate and inanimate nature.
The first relatively successful artificial system of the organic world was developed by a Swedish naturalist Carl Linnaeus(1707-1778). He took the form as the basis of his system and considered it an elementary unit of living nature. Related species united them into genera, genera into orders, orders into classes.
To designate a species he used two Latin words: the first is the name of the genus, the second is the species name (wild radish). This principle of dual nomenclature preserved in the system to the present day.
Disadvantages of the Linnaean system consisted in the fact that when classifying, he took into account only 1-2 features (in plants - the number of stamens, in animals - the structure of the respiratory and circulatory systems), which do not reflect true kinship, so distant genera were in the same class, and close - in different. Linnaeus considered species in nature to be immutable, created by the creator.
first consecutive theory of evolution living organisms was developed by a French scientist Jean Baptiste Lamarck(1744-1829). In the book " Philosophy of Zoology”, published in 1809, Lamarck suggested that during life each individual changes, adapts to the environment. He argued that the diversity of animals and plants is the result of the historical development of the organic world - evolution, which he understood as a stepwise development, the complication of the organization of living organisms from lower forms to higher ones and called "gradation" He proposed a peculiar system of organizing the world, arranging related groups in it ascending order - from simple to more complex, in the form of a "ladder". But Lamarck mistakenly believed that a change in the environment always causes beneficial changes in organisms.
English scientist Charles Darwin(1809-1882), having analyzed the huge natural material and data of breeding practice, in the main work " Origin of Species"(1859) substantiated the evolutionary theory, revealed the main patterns of development of the organic world.
He proved that a huge variety of species inhabiting the Earth, adapted to the conditions of habitat, were formed due to constantly occurring in nature multidirectional hereditary changes and natural selection. The ability of organisms to intensively reproduce and the simultaneous survival of a few individuals led Darwin to the idea that there is a struggle for existence between them, the consequence of which is the survival of organisms that are most adapted to specific environmental conditions, and the extinction of the unadapted. He considered the gradual complication and increase in the organization of living beings to be the result of hereditary variability and natural selection.
The significance of Darwin's theory lies in the fact that he introduced the natural-historical method into the study of nature: he established the main driving forces for the evolution of the organic world (hereditary variability and natural selection). The evolution of different species proceeds at different rates. For example, many invertebrates and reptiles have hardly changed over millions of years. And in the human genus, according to paleontologists, over the past 2 million years, several species have arisen and died out.
From the standpoint of modern teaching the most important factors of evolution are mutations And natural selection. The totality of these factors is necessary and sufficient for the implementation of the evolutionary process. Selection directly affects the phenotypes of organisms; as a result, not individual traits and alleles are selected, but entire genotypes that have a reaction rate. In genetic terms, evolution is reduced to directed changes in the gene pools of populations ( microevolution). Depending on the nature of changes in external conditions, different forms of selection can act on populations - driving, stabilizing and disruptive.
Modern evolutionary teaching enriched with data from genetics, molecular biology, and ecology.
The evolutionary doctrine of J. Lamarck
In 1809, the "Philosophy of Zoology" by the French scientist Jean Baptiste Pierre Antoine de Monet Lamarck (1744-1829) was published. In this work, the first attempt was made to create a theory of the evolution of species. She was unsuccessful. Lamarck built his theory on the following two propositions:
All living beings have an inner striving for perfection. It is the driving force behind evolution. The action of this factor determines the development of living nature, a gradual but steady increase in the organization of living beings from the simplest to the most perfect. Its result is the simultaneous existence in nature of organisms of varying degrees of complexity, as if forming a hierarchical ladder of beings.
The external environment directly affects the change in the shape of certain organs of living beings. “In every animal that has not yet completed its development, the more frequent and prolonged use of any organ strengthens this organ, develops it, increases it and gives it strength in proportion to the duration of use, while the constant absence of the use of any organ gradually weakens it, causes it to decline and makes it disappear."
He was wrong because, of course, he did not know the differences between the genotype and the phenotype. Exercise or no exercise can change the phenotype, but not the genotype. To prove that phenotypic changes are not inherited, A. Weisman conducted a long-term experiment in which he shortened the tails of mice for many successive generations. According to Lamarck's theory, the forced disuse of tails should have led to their shortening in offspring, but this did not happen. On this basis, Weisman postulated that the traits acquired by the body and leading to a change in the phenotype do not have a direct effect on the sex cells (gametes), with the help of which the traits are transmitted to the next generation.
In contrast to J. Lamarck, J. Cuvier, based on the structural features of the nervous system, formulated in 1812 the doctrine of 4 "branches" (types) of animal organization: vertebrates, segmented, soft-bodied and radiant. Between these types, he did not recognize any connections and transitions. Within the type of vertebrates, he distinguished 4 classes: mammals, birds, amphibians, fish. He described a large number of fossil forms and revealed that many of them belong to certain layers of the earth's crust. J. Cuvier was the first to propose to determine the age of geological layers from fossil remains, and vice versa. Based on the principles of "organ correlation" and "functional correlation", he developed a method for reconstructing fossil forms from the few surviving skeletal fragments.
Defending religious ideas about the creation and immutability of species and the absence of transitional forms between species, he put forward the theory of catastrophes to explain the change of faunas and floras observed in successive geological layers. In catastrophism geological history The Earth is considered as an alternation of long epochs of relative calm and relatively short catastrophic events that dramatically transformed the face of the planet. According to this theory, as a result of natural periodic disasters, a large part the globe all living things perished, after which its surface was populated by new forms that came from other places. The concept of catastrophism and repeated creative acts was consistent with the biblical concept of the creation of the world. Thanks to the ideas of J. Cuvier, ideas about progress in the organic world and about episodic events that break the monotony in the history of the Earth were widely disseminated. This contributed to the formation of ideas about the combination of evolutionary and spasmodic development.
In 1830-33, the work of the English naturalist C. Lyell "Fundamentals of Geology" was published. In this work, as opposed to the then popular theory of catastrophism, he developed the doctrine of slow and continuous change. earth's surface under the influence of constant geological factors that are active in the modern era (atmospheric precipitation, flowing waters, volcanic eruptions, etc.). The evolutionary theory of C. Lyell (actualism) was a major step towards a materialistic understanding of nature. C. Lyell considered the forces acting on the Earth to be constant in quality and intensity, he did not see their change in time and the development of the Earth connected with this.
The evolutionary theory of natural selection by Charles Darwin
Charles Darwin in his main work "The Origin of Species by Means of Natural Selection" (1859) summarized the empirical material of contemporary biology and breeding practice, based on the results of his own observations during travels, circumnavigation on the ship "Beagle", revealed the main factors of the evolution of the organic world. In the book "Changing Domestic Animals and Cultivated Plants" he presented additional factual material to the main work, and in the book "The Origin of Man and Sexual Selection" (1871) he put forward the hypothesis of the origin of man from an ape-like ancestor. At the heart of Darwin's theory - the property of organisms to repeat in a series of generations similar types of metabolism and individual development in general - the property of heredity.
Heredity, together with variability, ensures the constancy and diversity of life forms and underlies the evolution of living nature. One of the basic concepts of his theory of evolution - the concept of "struggle for existence" - Darwin used to denote the relationship between organisms, as well as the relationship between organisms and abiotic conditions, leading to the death of the less adapted and the survival of the more adapted individuals.
The concept of "struggle for existence" reflects the facts that each species produces more individuals than they survive to adulthood, and that each individual, during its life activity, enters into many relationships with biotic and abiotic environmental factors.
Darwin identified two main forms of variability:
A certain variability is the ability of all individuals of the same species in certain environmental conditions to respond in the same way to these conditions (climate, soil).
Uncertain variability, the nature of which does not correspond to changes in external conditions. In modern terminology, indefinite variability is called a mutation.
Mutation - indefinite variability, in contrast to definite variability, is hereditary. According to Darwin, slight changes in the first generation are amplified in subsequent generations. Darwin emphasized that it is precisely indefinite variability that plays a decisive role in evolution. It is usually associated with deleterious and neutral mutations, but mutations that turn out to be promising are also possible.
The inevitable result of the struggle for existence and the hereditary variability of organisms, according to Darwin, is the process of survival and reproduction of organisms that are most adapted to environmental conditions, and death in the course of evolution of the unadapted - natural selection. The mechanism of natural selection in nature operates similarly to breeders, that is, it adds up insignificant and indefinite individual differences and forms from them the necessary adaptations in organisms, as well as interspecies differences. This mechanism discards unnecessary forms and forms new species. The thesis of natural selection, along with the principles of the struggle for existence, heredity and variability, is the basis of Darwin's theory of evolution.
In Darwin's time, heredity was represented as a certain general property of an organism, inherent in it as a whole. In this regard, the Scottish researcher Fleming Jenkins entered the history of biology by raising objections to Darwin's theory. He believed that new useful traits of some individuals of a given species should quickly disappear when crossed with other, more numerous individuals. Darwin himself considered Jenkins's objections very serious, calling them "Jenkins' nightmare." These objections were refuted only when it became clear that the apparatus of heredity is formed by separate structural and functional units - genes.
According to C. Darwin and A. Wallace, the mechanism by which new species arise from pre-existing species is natural selection. This hypothesis is based on three observations and two conclusions:
Observation 1. Individuals that are part of the population have a large reproductive potential. Darwin and Wallace recorded this fact largely thanks to the work of T. Malthus "Treatise on Population". In it, T. Malthus drew attention to the reproductive potential of man and noted that the population is growing exponentially.
Observation 2. The number of individuals in each given population is approximately constant. All populations are limited or controlled by various environmental factors such as food resources, space, and light. Population sizes increase as long as the environment can still withstand their further increase, after which a certain equilibrium is reached. The population fluctuates around this equilibrium level.
Conclusion 1. Many individuals fail to survive and leave offspring. There is a "struggle for existence" in the population. Continuous competition between individuals for environmental factors within the same species or between members of different species leads to the fact that some organisms will not be able to survive or leave offspring.
Observation 3. Variation exists in all populations. The huge factual material collected during the travels by Darwin and Wallace convinced them of the importance of intraspecific variability. But they failed to identify the sources of all these forms of variability. G. Mendel will do this later.
Conclusion 2. In the "struggle for existence" those individuals whose traits are best adapted to the conditions of life have a "reproductive advantage" and produce more offspring than less adapted individuals. The decisive factor determining survival is adaptability to the environment. Any, even the smallest, physical, physiological, or behavioral change that gives one organism an advantage over another will act as a "selective advantage." Favorable changes will be passed on to the next generations, and unfavorable changes will be swept aside by selection, since they are unfavorable for the organism. Conclusion 2 contains the hypothesis of natural selection, which can serve as a mechanism for evolution.
The theory of evolution proposed by Darwin and Wallace was expanded and developed in the light of modern data from genetics, paleontology, molecular biology, ecology and ethology and was called neo-Darwinism. It can be defined as the theory of organic evolution by natural selection of genetically determined traits. In order to accept this theory as valid, it is necessary:
Establish the fact of changing life forms in time (evolution in the past).
Identify the mechanism that produces evolutionary change (natural selection of genes)
Demonstrate the evolution currently taking place (evolution in action).
Evidence of past evolution comes from fossils and stratigraphy. Data on the mechanism of evolution is obtained through experimental studies and observations regarding the natural selection of inherited traits and the mechanism of inheritance demonstrated by classical genetics. Information about the action of these processes in our time is provided by the study of populations of modern organisms, the results of artificial selection and genetic engineering.
So far, there are no firmly established laws of evolution. We have only well-supported factual data from the field of paleontology, the geography of the distribution of species, the classification system of K. Linnaeus, plant and animal breeding, comparative anatomy, comparative embryology, comparative biochemistry with hypotheses, which together constitute a fairly well-founded theory.
The evolutionary doctrine of free fallsThe very concept of nomogenesis, and arguments in favor of the fact that, contrary to Darwin, evolution is by no means random, but a regular process, were substantiated in detail by L.S. Berg in his classic works of the 20s, of which the main and most famous is Nomogenesis, or Evolution Based on Regularities. Berg puts it this way:
Is evolution a random process, which is due to only two factors: chaotic mutations and natural selection, or is evolution a fundamentally regular process, the identification of a certain trend, an immanent law that directs its course?
In such a formulation, the question may seem not quite correct and even pointless, because even basically random processes can obey very strict statistical laws. More precisely, its essence can be understood from a simple analogy: although the development of an individual organism is influenced by many random factors, there is no doubt that the main determining factor is the internal information embedded in the genes. Its entire history is the unfolding, the implementation of the program, on which only depends what will grow, for example, from a given seed a birch or a pine.
The entire evolution of the biosphere is, according to Berg, the unfolding of some kind of law, or it may be more correct to say, a multivariate program, which also contains numerous ways of its implementation. Therefore, Berg called his concept nomogenesis, contrasting it with the Darwinian concept of "tychogenesis", that is, development based on chance. Can we today, at least in the most general outlines, imagine what this law looks like? No, but our ignorance does not mean that there is no such law.
Imagine that a certain mathematician studying tables of random numbers is surprised to find in them stable repetitions, "motifs", "rhythms and rhymes", "homologies", the presence of which cannot be explained by chance. Let further he be able to find something similar in other sequences obtained with the help of independent and different generators. What hypothesis can such a mathematician put forward? He can, first of all, assume that the series he is studying are not at all random, but there is a rather intricate manifestation of a previously unknown natural pattern.
In his works, Berg summarizes the vast factual material accumulated by the beginning of the 20th century, which testifies in favor of the nomogenetic nature of evolution. This material speaks of numerous "rhythms and rhymes" present in the system of living forms, which cannot be called accidental. As an example, let us cite the fact of the so-called anticipation of features (phylogenetic acceleration). It is known that in the embryonic phase there are signs of those stages through which the evolution of this group supposedly passed. At one time, E. Haeckel, an ardent supporter and propagandist of Darwinism, formulated a rule called the biogenetic law: ontogeny repeats phylogeny. For some reason, it is believed that it serves as a direct argument in favor of the Darwinian concept, although it can only be understood as evidence that evolution takes place at all, which, of course, few people doubt.
Much less frequently discussed is the fact that the opposite phenomenon, symmetrical in time, also takes place: "individual development can not only repeat phylogeny, but also precede it." This rule applies not only to individual organisms, but also to their entire groups: the phylogeny of any group can be ahead of its time, realizing forms that are normally characteristic of higher-ranking organisms in the system. This means that the signs that appear as a result of anticipation could not have come about as a result of the operation of the Darwinian mechanism. As an individual development, evolution is a process of unfolding, implementation of an already existing program.
The nomogenetic direction in the theory of evolution is similar to the nomothetic direction in systematics. For a better understanding, it is useful to say a few words about the classification of variants of evolutionary theories:
nomogenetic - the presence of specific laws of development or limited morphogenesis;
ectogenetic - the role of external factors in evolution;
telogenetic - the role of active adaptation.
The theory of nomogenesis can be divided into two areas:
The doctrine of the limitation of shaping.
Variability in Darwin's time was considered unlimited, like "wax plasticity". This was proved by the fact that any sign showed greater or lesser variability. Long before Mendel, it was noticed that during fertile crossing, some kind of especially shaken variability is observed, as if not obeying any laws. Mendel subordinated this imaginary chaos to strict mathematical laws: instead of wax plasticity, which allows an infinitely large number of possible modalities, we get not only a finite, but not even a very large number of them. Having somewhat risen in the taxonomic level, we meet the law of homological series of N.I. Vavilov (1920).
The third form of nomogenesis in this sense can be considered what is called biochemical nomogenesis, for example, biochemical differences between primary and deuterostomes. An important substance used by protostomes to build the external skeleton - chitin - is completely absent in the two main types of deuterostomes - echinoderms and vertebrates. Echinoderms and vertebrates develop an internal calcareous skeleton on a connective tissue basis and flexure of the body or antimere is obtained from the articulation of internal calcareous elements or vertebrae (vertebral column and arm).
Finally, the fourth form of nomogenesis in the sense of limited morphogenesis can be called telogenetic nomogenesis, that is, a similar resolution of certain tasks, regardless of the nature of the factors that carry out this resolution. This phenomenon has long been known (the similarity of ichthyosaurs, dolphins and fish, the eyes of vertebrates and cephalopods), but the whole latitude is not sufficiently realized and some interesting directions are little known.
The doctrine of the limited form formation outlines the possibilities of predicting the forms of living beings on other planets. There is a huge difference of opinion here, from the assumption of the likelihood of the emergence and existence of organisms so close to humans that productive interbreeding is possible, to the denial of any foresight of the structural features of alien creatures. The first extreme can hardly be defended by a serious biologist, but such formations as, say, DNA, chromosomes, cells, intestines, metamerism, limbs, chitin, arise or can arise in very similar form not only in parallel, but also convergently*. The fundamental possibility of the existence of plants and animals on other planets is not denied, therefore, for higher taxa, an independent emergence is conceivable.
It can be assumed that types, and perhaps some classes, can arise independently, and on distant planets we have the right to expect meetings with organisms that we will attribute to protozoa, coelenterates, annelids, arthropods, and even insects. Meeting on another planet sentient being, we, of course, distinguish it from a person. But, most likely, there will be some signs of similarity: he will have a head in front of him, in which there will be developed brain, there will be twin eyes built according to the requirements of geometric optics, there will be paired limbs, the forelimbs will be tools of labor, and not movement, which means they will have a semblance of fingers, although the number and structure of these fingers may be completely different from ours. One of the names of Lobachevsky's geometry was "imaginary geometry". Now there is a need for "imaginary biology"
The doctrine of directed development paths
The limitation of shaping does not impose any restrictions on the form of development paths. But along with undirected, zigzag evolution, which undoubtedly exists at the lowest level of evolution, there are also directed forms that have long been denoted by different terms, the term "orthogenesis", or rectilinear development, is especially popular. Orthodox Darwinists sharply criticized the theory of orthogenesis: they denied that orthogenesis is the main and even the only mode of evolution, and this objection is quite reasonable; the causal explanation of orthogenesis as a result of the influence of external conditions was criticized and another term was proposed - "orthoevolution"; cases of development in a spiral were indicated, where it is not necessary to speak of rectilinear development; finally, since the main evidence of orthogenesis - parallel development - is gaining more and more powerful factual support, Darwinists try to save the day by explaining this parallelism by selection in the same direction, proposing the term "orthoselection".
Of course, the terms "orthoselection", "orthogenesis" and others are not entirely accurate. But there is another form of nomogenetic directed development, which can be called nomogenesis only in the initial stage, just as the cannonball flies from a cannon for the first time almost in a straight line. This form of development includes three segments:
Very fast progressive evolution, a special case - aromorphoses in the terminology of A.N. Severtsev;
The transition from a vertical line to a horizontal one is a conservative evolution;
Severtsev's idioadaptation is a special case, not a general law, since evolution may not be adaptive;
Regressive stage: loss of variability, regressive development and extinction. Apparently, in a number of cases, a way out of the impasse of evolution is possible through pedogenesis or otherwise.
Questions of the origin of the main kingdoms of wildlifeThe unit of classification for both plants and animals is the species. In the most general sense, a species can be defined as a population of individuals that have similar morphological and functional characteristics, have a common origin, and under natural conditions interbreed only with each other.
A species can also be defined as a set of populations within which interbreeding is possible, or as a group of populations with a common gene pool. Any of these definitions implies as the main thing: one species is separated from another by a reproductive barrier, interbreeding is impossible between them.
To solve the problem of speciation means to explain how elementary evolutionary changes in a population can lead to the formation of new species, genera, families and orders and how barriers arise that prevent interbreeding between emerging species. Any factor that makes interbreeding between groups or organisms difficult is called an isolating mechanism.
One of the most common types of isolation is geographic isolation, in which groups of related organisms are separated by some kind of physical barrier. For example, in the mountains, a given area usually contains more different species than the same area in the plains. As a rule, geographic isolation is not permanent: separated closely related groups sometimes meet again and can continue interbreeding, unless during this time genetic isolation arose between them, that is, sterility during crossing. Genetic isolation is due to mutations that occur randomly, independently of other mutations that affect morphological or physiological traits. Therefore, in some cases it may occur very slowly, when long-term geographical isolation will create noticeable differences between two groups of organisms, and in other cases it may occur within the same, otherwise homogeneous group.
Usually the offspring of a cross between different types are sterile, however, sometimes as a result of hybridization of representatives of two different, but very close species, a new species arises. A hybrid form can combine the best features of both parental species, resulting in a new form that is better adapted to the environment than either of the original forms, or, conversely, worse features with a corresponding outcome.
The isolation required at the initial stages of speciation can be provided not only by geographical barriers between populations: sometimes isolated groups of individuals arise within the same population, and this can lead to the formation of new species. This method of speciation is called "sympatric" (from the Latin words sim - together and patria - homeland). This method differs from the previous one only in isolation factors, while the reasons leading to morphological divergence and the formation of a system of isolating mechanisms are the same as in the case of geographic speciation.
In ecological speciation, the isolating factor is natural selection (its special form is disruptive or fragmenting selection) in combination with the heterogeneity of the habitat. To successfully complete the speciation process, the isolation must be as complete as possible and last for a long time. These conditions are difficult to fulfill in a natural environment, so examples of ecological speciation are quite rare.
Theoretically, ecological speciation can also occur in the absence of primary isolation between emerging species. For this, it is necessary that a disruptive selection act in the population, directly aimed at the formation of a system of isolating mechanisms. This conclusion was made on the basis of the analysis of computer models and is confirmed in experiments with the fruit fly Drosophila. It is probable that it is precisely in this way - as a result of ecological speciation without primary isolation - that complexes of closely related fish species occurred in isolated lakes.
Origin of multicellularity in animals and plantsThe evolution of each given form of living organisms occurs over many generations. During this time, many individuals are born and die, but the population maintains continuity. Thus, the evolving unit is not an individual, but a population. A population of similar individuals living in a limited area and interbreeding with each other is called a deme or genetic population. The next larger category is the species, which consists of a number of loosely demarcated demes.
In nature, demes and species tend to remain the same for many generations. Such immutability means that during this time there have been no changes either in the genetic constitution of the deme or in environmental conditions affecting the survival of these organisms. Each population is characterized by a certain gene pool. Each individual in a population is genetically unique.
The process of speciation should consist of two inseparable components:
Form deviations (centrifugal component).
Shape retention - (centripetal component).
Education new form- as a taxonomic reality is the result of the interaction of these two processes.
Hence two questions:
The first question is what is the nature of variability, that is, what is its internal source, what are its properties, and what provokes variability (in this context, what external circumstances).
The second question - (especially important when accepting the idea of transformism) - is how the actual diversity, that is, what determines the constancy of form in generations, is maintained on the historical and, moreover, geological scale.
One can speak of "internal" causes and "external" conditions of speciation. Two facts - the fact of the diversity of forms (species, breeds, varieties, individuals) and the fact of the constancy of form in one genealogical line - led to the understanding of variability and heredity as two independent fundamental factors, in principle determining the possibility of such a change in forms, which leads to a discrete and stable diversity of taxa over time. In procedural terms, variability and heritability act as centrifugal (changing) and centripetal (retaining) factors. Their complex interaction determines the process and the end result (sustainable change). These factors are called "internal" causes of speciation.
There are "external conditions" favorable (provoking) or unfavorable (suppressing - selectively or totally) phenotypic variability. This:
a) a demographic factor, often associated with a geographical or biotopic factor (in total - the spatial isolation of a small group or the appearance of a small isolate);
b) ecological factor (physical and reproductive survival of the form in a specific ecological context). The last factor acts as a measure of the sufficient correspondence of the form to the environment and as elimination selection in the absence of such correspondence.
The attitude towards "internal" and "external" factors of speciation varies in different concepts. This relationship determines the essence of the concepts, that is, their conceptual arsenal, the semantic meaning of the central concepts (often the same terminologically) and lexical devices.
The Question of Transitional Theories of the OrganismAfter the widespread dissemination of the teachings of Charles Darwin, one of the first critics who pointed out a weak point in the theory was the Scottish researcher F. Jenkins. In 1867, he noticed that in Darwin's theory there is no clarity on the question of how certain changes are accumulated in the offspring. After all, at first, changes in the trait occur only in some individuals. After crossing with normal individuals, not accumulation, but dilution of this trait in the offspring should be observed. That is, ½ changes remain in the first generation, ¼ changes remain in the second, and so on. up to the complete disappearance of this symptom. C. Darwin never found an answer to this question.
Meanwhile, the solution to this problem existed. It was received by the teacher of the monastery school in Brno (Czech Republic) G. Mendel. In 1865, the results of his work on the hybridization of pea varieties were published, where the most important laws of heredity were discovered. The author showed that the signs of organisms are determined by discrete hereditary factors.
Even before the publication of Charles Darwin's book, he wanted to trace the fate of changes in genotypes in different generations of hybrids. The object of the study was peas. Mendel took two varieties of peas - with yellow and green seeds. Crossing these two varieties, he found in the first generation of hybrids peas with only yellow seeds. By self-pollination of the resulting hybrids, he received the second generation. Individuals with green seeds appeared in it, but there were noticeably fewer of them than with yellow ones. By counting the number of both, Mendel came to the conclusion that the number of individuals with yellow seeds is related to the number of individuals with green as approximately 3:1.
In parallel, he conducted a series of other experiments with plants, tracing any trait in several generations. In each experiment, only one of the parental traits was manifested in the first generation. Mendel called it dominant. He called the temporarily disappearing trait recessive. In all experiments, the ratio of the number of individuals with a dominant trait to the number of individuals with a recessive trait among hybrids of the second generation was on average 3:1.
So, it could be argued that when plants with opposite traits are crossed, it is not the dilution of traits that occurs, but the suppression of one trait by another; in this regard, it is necessary to distinguish between dominant and recessive traits.
Mendel went further in his experiments. He self-pollinated second-generation hybrids and obtained third- and then fourth-generation hybrids. He found that second-generation hybrids with a recessive trait, with further reproduction, do not split either in the third or in the fourth generation. Approximately one third of second-generation hybrids with a dominant trait behave in the same way. Two-thirds of hybrids with a dominant trait are split in the transition to third-generation hybrids, and again in a ratio of 3:1. The hybrids of the third generation with a recessive trait and a third of the hybrids with a dominant trait obtained during this splitting do not split during the transition to the fourth generation, and the remaining hybrids of the third generation split, and again in a ratio of 3: 1.
This fact demonstrates an important circumstance: individuals with the same external features may have different hereditary properties, that is, one cannot judge the genotype with sufficient completeness by the phenotype. If an individual does not detect splitting in the offspring, then it is called homozygous, if it does, it is called heterozygous.
As a result, G. Mendel formulated the law of uniformity of hybrids of the first generation: the first generation of hybrids, due to the manifestation of only dominant features in them, is always uniform. This law is also called the first law of Mendel or the law of dominance. However, the results of his research remained practically unknown for almost 35 years - from 1865 to 1900.
AnthropogenesisAnthropocentrism and biospheric thinking Anthropocentric thinking and biospheric thinking are two fundamentally different types of worldview. This concerns: the nature of the problems - methodological, research, economic and industrial, etc.; many people - from individuals, groups of people united by social, religious, national or other affiliation, to the population of countries, continents and humanity as a whole; the size of the territory subject to anthropogenic impact - from tens to hundreds of square meters, parts of the landscape to vast regions, the vitasphere and the biosphere as a whole.
One of the main signs of the difference between the two worldviews is the attitude to time. With the anthropocentric approach, as a rule, they are limited to short-term estimates and forecasts - a maximum of the next decade, while with the biospheric approach, long-term estimates and forecasts - at least decades and centuries - should be the basis. Anthropocentrism focuses on the destinies of living people and their momentary interests, and in extreme cases - their children and, in a completely abstract way, grandchildren. While biospheric thinking will cover a series of generations and will really acquire, thus, the right to speak about the fate of mankind.
Anthropocentrism localizes the analysis of impacts on natural complexes in space. The biospheric approach recognizes the importance of the possible "spreading" of effects over vast territories. An anthropocentric approach, implemented in some industrial project, presents its opponents with the requirement: "Prove that this project will be harmful in some way." The biospheric approach requires arguments in favor of the fact that the existing state of nature will not be worsened. Ultimately, anthropocentrism formulates the target function as "it would be better for a person today, and then we'll see", biospheric thinking - "cannot be better for a person if the deterioration of natural complexes is not excluded."
Experience shows that the anthropocentric approach is content with the residual principle of financing fundamental research, which, according to V.I. Vernadsky, the basis for the formation of biospheric thinking: "The main geological force that creates the noosphere is the growth of scientific knowledge."
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