Introduction
Even though science was progressing and accumulating the facts, which were extremely contradictory to the metaphysical world outlook, the views on the immutability of nature continued to dominate in the XIX century. Some problems were impossible to solve. The first of them was the problem of conversion of one organic form to another. Nobody proved that species may give a new species form. The second problem was the problem of the feasibility of organic beings.
The essence of it is in the question: why is each new organic form adapted to their environment if there is a process of historical development? Before Darwin’s solution, this problem was viewed from the metaphysical position, and the appropriateness was recognized as absolute and original. The third problem concerned the driving forces and the factors of evolution. All these problems were firstly solved by Darwin and were highlighted in the evolutionary theory of Darwin, who revolutionized the science of biology.
Darwin and XIX century
The XIX-th century is remarkable for its controversial character. It should be mentioned that the most controversial issue of that time was the problem of science and religion. It was a great revolution in human knowledge about their creation. People got new imaginations about their nature.
It should be admitted that the first thought about evolution could be found in the science of Ancient times. These ideas were developed by Epicurus and Anaximander. Nevertheless, the theories of evolution were officially recognized in the XIX-th century and were worked out by the scientists Jean-Baptiste Lamarck and Charles Darwin. The concept of natural selection made a great revolution and was firstly discussed in the Origin of Species by Charles Darwin. Natural selection was explained by Darwin as a mechanism of evolution. (Mayr, 2002, p137)
Darwin’s theory
Darwin was the first who gave a materialist interpretation of organic appropriateness based on the theory of natural selection. He showed its relative character of organic appropriateness and opened the ways of adapting. He showed that the adaptation of species based on selection can not be absolute, they are always relative and are adequate only to the environmental conditions in which the species exist for a long time. For example, the adaptation of fish is needed only in the aquatic habitat and is not suitable for terrestrial life; the green color of the locust is good for the green vegetation.
Darwin thought that the emergence of new species is a gradual process, which is fulfilled through the accumulation of useful individual changes, increasing from generation to generation. The greater the differences are between the species in structure and physiological character, the greater the number of groups that may exist in the territory due to struggle for existence. With each generation, the differences become more and more obvious and the intermediate forms, similar to each other, are dying. The process of speciation, according to Darwin, is based on the principle of divergence, i.e. due to differences in characters. Thus, the result of the selection will be the emergence of adoptive features and on this basis, species diversity will be formed. (Milner Richard, Gould Stephen Jay, andTattersall Ian, 2009, p224).
The diverse and changing environmental conditions contribute to the evolution of species in the direction of the more complex organization (mammals, insects). If the species live for a long time in a homogeneous environment outside the stiff competition, the level of their organization can remain at a relatively low level (Amphioxus). In the constantly changing environmental conditions, some species are decreasing in number, and they are replaced by others, which are better adapted to new conditions.
It should be emphasized that Darwin was the first who proposed the scientific explanation of the evolutionary process. He pointed to the driving forces of evolution: natural selection, genetic variation, the struggle for existence. He gave the materialist explanation of the mechanism of speciation and the causes of diversity of species, and also explained the reasons for appropriateness. (Milner Richard, Gould Stephen Jay, and Tattersall Ian, 2009, p224).
The starting position of Darwin’s theory is his claim about the presence of variability in nature. Variability is a general property of organisms to acquire new features – the differences between individuals within a species. Darwin further noted the fact that the organism is changed in any direction, transmitted to the offspring tend to change more in the same direction if there are the conditions that caused this change. This is the so-called lasting variability that plays an important role in evolutionary transformation. Studying the variability of plants and animals, Darwin noted several important regularities in the change of various organs and systems in the body.
Darwin distinguishes between two kinds of artificial selection – methodical, or conscious, and unconscious selection. The essence of methodical selection is as follows: the breeder sets a task for those features that he wants to develop in the breed. First of all, these features must be economically valuable, and some of them must satisfy the aesthetic needs of man.
Thus, the methodical selection is a creative process that leads to the formation of new breeds and varieties. Using this method, the breeder, as a sculptor creates a new organic form.
Unconscious selection is made by people without any certain pre-task. Darwin showed that such a type of selection works. For example, a farmer who has two cows and wants to use one of them for meat would kill the one that produces less milk. Such a primitive form of selection was called unconscious selection.
Darwin proved that the process of selection takes place in natural conditions without human intervention. It is because of natural selection there is a continuous process of adaptation, improvement of devices, divergence, and speciation, i.e. the process of evolution.
The scheme of natural selection according to Darwin is as follows: because of the uncertainty variability within a species inherent for all organisms new individual features appear. They differ from conventional animals of this group (species) according to their needs. Due to various adaptations of old and new forms, the struggle for existence leads some form to elimination. As a rule, the intermediate organisms disappear. The intermediate forms are faced with intense competition. The process of divergence occurs in nature all the time. As a result, new species appear and the varieties of such separation eventually lead to the emergence of new species (Darwin Charles and Huxley.
Darwin’s evolutionary theory is a coherent theory of the historical development of the organic world. It covers a wide range of issues, the most important of which is the evidence of evolution, the identification of the driving forces of evolution, the determination of the ways and patterns of evolution. Historically the process of evolution can be divided into 3 stages.
The first stage is characterized by the emergence and development of life at sea. At the primary ocean, unicellular algae appeared. Then, during the retreat of the sea on the vacant plots of land lichens appeared, and later – mushrooms and mosses. A further complication of the primary plant led to the emergence of more intricate vascular plants.
The second stage was marked by the flowering of monocots and the emergence of dicotyledons, as well as by the first land animals.
The third stage is characterized by the appearance of modern plants and animals in the world.
According to Charles Darwin, the main result of evolution is to improve the adaptability of organisms to environmental conditions, and this entails the improvement of their organization. As a result of natural selection specimens with useful features for their prosperity stay. Darwin brings a lot of evidence of increasing the adaptation of organisms, which is determined by natural selection. For example, it is the spread of protective coloring among animals (the color of areas in which they live, or the color of individual items. Many animals have special protective adaptations such as warning color.
Many animals which have no specific remedies on their body and color imitate the protected predators (mimicry). Many animals have needles, thorns, chitinous cover, shells, scales, etc. All of these devices could appear only as a result of natural selection, ensuring the existence of the species in certain circumstances (Darwin Charles and Huxley.
However, Darwin noted that the adaptation of organisms to the environment as well as their perfection is relative. When the conditions are changing suddenly the useful features may be useless or even harmful.
Another important result of evolution is the growth of the natural diversity of species groups, i.e. systematic derivation of species. The total increase in diversity of organic forms performs very complicated relationships that occur between organisms in nature. Therefore, in the course of historical development, the most highly organized forms usually have the greatest advantages. Thus there is the development of organic life from the lower to the higher forms. However, despite considering the fact of the progressive evolution, Darwin does not deny the morphophysiological recourse (i.e. the evolution of forms, adapting to environmental conditions that go through the simplification of the organization), as well as a direction of evolution, which does not lead to complication or simplification of the living forms. The combination of different lines of evolution leads to the simultaneous existence of forms, differing in the level of organization.
Consequently, there can be both progress and regression for the evolution of the different forms. The regression is aimed at achieving the goal – the improvement of the forms, through the adaptation to changing habitat conditions. Here it would be appropriate to mention the concept of the phylogeny. Phylogeny means a gradual change of different forms of the organic world in the process of evolution.
There is one more branch of biology which is closely connected with the evolution theory. It is developmental Biology and it studies the development of the individual in contrast to the development of the species (phylogenesis).
Thus, the driving forces of evolution, according to Darwin, are genetic variation and natural selection. Variability is the basis of new features in the structure and functions of organisms and establishes the inheritance of these traits. As a result of the struggle for existence only the strongest individuals are primarily involved in survival and reproduction e.g. natural selection and the result of natural selection is the emergence of new species. It is important to emphasize that the adaptation of organisms to the environment is relative.
The essence of the Darwinian concept of evolution is based on the series of logical, verifiable experimentally confirmed points (Darwin Charles, Glick Thomas F., and Kohn David, 1996, pp94 – 113) :
- Within each species of the living organism there is a huge scope of individual genetic variability in morphological, physiological, behavioral, and any other grounds. This variability may be continuous, quantitative, or qualitative intermittent, but it is always there.
- All living organisms multiply in geometric progression.
- The vital resources for any kind of living organisms are limited, and therefore must be a struggle for existence, between the individuals of one species or between the individuals of different species, or for natural conditions. The concept of “struggle for existence” according to Darwin includes not only the struggle of the individual for life but also the struggle for success in reproduction.
- In the struggle for existence, survival, and producing offspring the best are the adapted individuals, with those variations which happen to be adaptive to these environmental conditions. This is a fundamentally important point in the arguments of Darwin. The variations arise not directly – in response to the environment, but accidentally. Few of them are useful in specific circumstances. The descendants of the surviving individuals who inherit a useful deviation, which allowed their ancestors to survive, are more adapted to this environment than other members of the population.
- The survival and reproduction of superior fittest individuals Darwin called natural selection.
- Natural selection of individual isolated species in different conditions of existence gradually leads to a divergence like these varieties and, ultimately, to speciation.
The most important achievement of Darwin is the fact that he has established the mechanism of evolution, explaining the diversity of living creatures, and their wonderful appropriateness, suitability to the conditions of existence. This mechanism is a gradual natural selection of random undirected hereditary changes. (Thomas, 1996, p113)
Conclusion
As holistic materialist doctrine Darwinism made a revolution in biology, it had a huge impact on the natural and social sciences, culture in general. However, during the life of Darwin, along with the wide acceptance of his theory in biology, some trends were against these discoveries. The controversy on the basic problems of evolution theory has continued up to nowadays.
Darwin’s evolutionary theory was one of the first successful examples of solutions to the important problems of the development of wildlife from the standpoint of natural-scientific materialism. It had a tremendous influence on all biological sciences, by adopting an understanding of wildlife and giving a materialist explanation of the phenomena of appropriateness.
The positive side of Darwin’s theory is its close connection with the breeding practices, which served as the basis for the construction of evolutionary theory. To analyze the evolution of the organic world, Darwin used not only the data of practices but critically reviewed its findings in the light of biology and agriculture. This is consistent with the generally recognized principle that the practice is the main criterion of truth, and led to a fundamental restructuring of biology and solving many problems.
Works cited
Darwin Charles, Glick Thomas F., and Kohn David . Darwin on Evolution: The Development of the Theory of Natural Selection. Hackett Publishing Company, 1996. Print.
Darwin Charles and Huxley Julian. The Origin Of Species: 150th Anniversary Edition. Signet Classics. 2003. Print.
Mayr Ernst. What Evolution Is. Basic Books, 2002. Print.
Milner Richard, Gould Stephen Jay, and Tattersall Ian. Universe: Evolution from A to Z. University of California Press. 2009. Print.
Thomas S. Kuhn. The Route to Normal Science. 3d edition. New York: 1996. Print.