EVOLUTION #3

THEORIES OF EVOLUTION

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The theories of evolution are an attempt to explain how evolution has taken place. Two such theories are explained below.

LAWMACK THEORIES OF EVOLUTION

Jean lawman, a French zoologist was the first to suggest that organisms undergo evolution. His theory which was propounded in 1801 is also called the theory of use and disuse.

Lawman contribution or postulate are as follow:-

• That great changes in environment result in corresponding changes in the species.
• That these changes cause the organism to form new structure or habit to adjust to the new prevailing environment.
• That organism then develop specialized characters by use and disuse of organs
• That frequently used organs become well developed while the ones not used degenerate and become atrophied or useless.
• That the well developed or dominant acquired character is inheritable.

Lamarck used the long neck of a giraffe to give an example of the theory.This long neck of giraffe arose from the need to browse on tree tops. since this was a useful adaptation subsequent the tois acquired character.

DARWINS THEORY OF EVOLUTION

Charles Darwin,. a British naturalist in 1859 also propounded another theory of evolution. His theory is known as Darwin theory of natural selection.