Charles Darwin in his book ‘The Origin of Species‘ or the preservation of favored races in the struggle For life (1859) proposed that there is inherited variation (polymorphism) in populations of animals and plants, more creatures are born than can survive (a struggle for existence), and individuals carrying certain favorable variants are more likely to survive and pass them on others (natural selection). Over long periods natural selection gives rise to new forms of life (the origin of species).
Lamarck gave his theory in his book “Philosophie Zoologique” (1809). He states that changes in the environment bring about bodily changes in individuals by their inner urge. Such changes are developed by use and are handed over to the next generation. Thus his theory centers around the idea of use and disuse of parts and inheritance of acquired characters.
The following are the points of difference between Lamarckism and Darwinism:
The theory believes in the presence of an internal vital force in all organisms.
Darwinism does not believe in the existence of any internal vital force.
Lamarckism considers the perfecting principle to be the guiding principle for all organisms to achieve harmony with the environment.
Nature selects only those individuals which are adapted to the environment in which they live.
Modifications and even new organs can develop due to new needs, desires, and conscious reactions.
They do not form part of the theory of natural selection by Darwin.
The use and disuse of organs bring about their development and degeneration respectively.
An organ can develop further or degenerate only due to variations appearing in that direction.
Change in the environment produces variations.
Variations are already present. Changing environment selects some particular variations suitable for it.
It does not consider any struggle for existence.
The struggle for existence is a very important ingredient of this theory.
All the acquired variations are transferred to the next generation.
Only the selected variations are transferred to the next generation.
It does not believe in natural selection.
Darwinism is based on natural selection and survival of the fittest.
So, we can conclude by saying that both Lamarck and Darwin contributed to the basic framework of evolutionary theory. Lamarck was the first person to offer a completely comprehensive mechanistic theory. And, Darwin too has been credited with giving the first systematic as well as comprehensive approach in the perspective of evolutionary development.