How Can You Explain The Theories Of Evolution?

Several theories have been put forth to explain the way how evolution might have taken place.

Lamarckian theory: It was propounded by jean Baptiste de Lamarck (1744-1822) in 1809 in his book "philosophic zoologique". The theory states that environment moulds the organisms towards better adaptation and all the changes produced are inherited by successive generations as a result of which entirely different organism is produced representing a new species.

Darwin's theory of natural selection: Charles Robert Darwin (1809-1882) and Alfred Russell Wallace (1822-1913) in 1858 postulated a theory stating that there is a sort of over production in all the organisms giving rise to "struggle for existence" and consequently the "survival of the fittest". So each tries to adapt itself to an organization suitable or fit for existence. The survival of fittest and death of unfit is known as "natural selection". The helpful variations are transmitted from generation to generation finally resulting in an entirely different species.

Neo Darwinism: It is the modified form of Darwin's theory of natural selection by Julian Huxley. Neo Darwinian theory states that though there is over production, the population remains constant due to "struggle for existence" and "survival of fittest", but there is selective in heritance also.