Charles Darwin (1908-1882) in his book ‘The Origin of Species”, or the ‘Preservation of favoured races in the struggle of life’ (1859) proposed that there is inherited variation (poly morphism) in populations of animals and plants, more creatures are born than can survive (a struggle for existence), and individuals carrying certain favourable variants or 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 “Philosophic Zoologique” (1809). He states that changes in environment brings about bodily changes in individual by their inner urge. Such changes are developed by use and are handed over to the next generation. Thus his theory centres round the idea of use and disuse of parts and inheritance of acquired characters.
Each theory was different in its own way. The striking differences are as follows:
| Darwin | Lamarck |
| Darwinian theory deals with the vertical andhorizontal aspects of evolution in a complete way,i.e.,he examined the verticalphenomenon and adaptive change with thehorizontal phenomenon of the diversity ofpopulations. | Lamarck concentrated more on vertical aspect of evolution, i.e., he paid more attention to the problem of origin of adaptation |
| Darwinism is based on evolution by common descent. He realized that life isderived from a single origin | This component is missing inLamarckism. |
| Darwinism emphasizes that diversity is dueto struggle for existence and favourablevariations. | Lamarckism emphasizes that diversity is due to intrinsic perfecting force namely clanvitae. |
| Darwin considered population as unit ofevolution | Lamarck considered individual as unit of evolution |
| It emphasizes modification of population | It emphasizes modification of individual |
| Darwinism also emphasizes that nature selects organisms in a population for evolution. | Lamarckism emphasizes that nature directs organisms for evolution. |
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.