Criticism of Lamarckian theory of evolution
Lamarck's Theory about evolution with criticism...
French naturalist Jean-Baptiste Lamarck in his Philosophic Zoologique in 1809 Proclaimed and propagated a rational theory of evolution. His theory of evolution is figured out as the inheritance of acquired characteristics. The basic premise of Lamarckian theory is that change in organisms over time is a necessary condition. However, according to him, this change is not only the result of direct acts on the environment. Rather, the transformation of the physical structure is the reason for the change. In all cases, evolution follows certain rules. These rules determine the sequence and characteristics of evolution.
Lamarck formulated these principles in his theory of evolution in four ways.
1st formula: Intrinsic energy tends to increase the size of the organism: In the living world there is an intrinsic energy constantly working to achieve the complex state from the simple state. This results in the growth of the organism and its organs. Growth continues up to a specific limit.
Second formula: Direct Impact of Environment on Organisms: To survive under the direct impact of a changing environment, there are specific structural changes in the organs of the organism due to new needs and continuous lack.
Third formula: Use and Disuse: The growth, development, and structure of an organ are constantly dependent on its use. When an organ is used more, it gradually increases and progresses towards perfection. Again the constant disuse of any organ renders him inactive
As a result, its development is hampered, and even its decline and extinction become inevitable.
Fourth formula: Transmission of Acquired Characteristics: The characteristics acquired during the life of an organism are transmitted and developed from generation to generation as hereditary characteristics.
Lamarck, in his Philosophic Zoologique, pointed out that the organic changes that occur in living organisms are acquired through continuous changes under the direct influence of the environment. When there is a transformation in the environment, there is a need for a shift in the organism. As a result, certain organs are perfected due to special needs. On the other hand, the organs will be destroyed if they are of no use.
Criticism of Lamarckism: Lamarck's theory of evolution has been criticized in various ways by many philosophers and natural scientists as it fails to provide a correct explanation of the underlying evolutionary process. They are mentioned below.
No single study found support for the heritability of acquired traits. Lamarck's theory does not apply to higher organisms. But in the case of lower unicellular organisms, in which the germplasm is slightly separate or united, this doctrine is applicable. Attempts to do so rarely occur in the plant kingdom. The giraffe's continuous neck is long.
Some sources support the theory of vitality which is inconsistent with scientific realist concepts. Lamarckism proposes a dogma without evidence. It is now clear that the new organism develops from the germ cell of the parent and never from the somatic cell.
In the early stages of an organism's growth, germ cells are isolated and are not affected by body cells. There are many cases where Lamarckian inheritance is impossible or highly restricted.
The internal environment of advanced mammals is highly stable. Blood temperature, salt content, and blood acidity remain unchanged through extensive and specialized techniques. Germ cells, like other cells in the body, are released into the internal environment through the bloodstream.
In such a situation, it is not understandable how the change in the external environment will be transmitted to the offspring. A change in the internal environment acts as an effective shock absorber of changes occurring in the external environment. Nevertheless, advanced mammals evolve and adapt as quickly as lower animals that have no such buffering action.
Insects caused many problems with Lamarck's theory. Social is one such insect. The number of fertile insects in this colony is low. In this situation, the question of how a special innate characteristic and structures of workers will evolve from two Lamarckian angles. As workers do not participate in reproduction, they are not able to transfer acquired traits. For these reasons, most scientists in modern biology have rejected Lamarckism.
I am a student of zoology and credit for this article goes to Madam Rita Parvin, Sir Shamol Shordar, Sir MD Rafikul Islam, Sir Shafiullah Shopon
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