Main Difference – Darwinism vs Lamarckism
Biological evolution is defined as the process by which the characteristics of organisms change over several successive generations in the aspects of genetic variation and natural selection. It can also be explained as a change in the gene frequency in a population. Darwinism and Lamarckism are two theories put forward to explain this concept of biological evolution. The main difference between Darwinism and Lamarckism is that Darwinism is based on the concept of natural selection whereas Lamarckism is based on the concept of an internal vital force which is present in all living organisms.
In this article, we are going to discuss,
1. What is Darwinism – Theory and Concepts, Characteristic Features
2. What is Lamarckism – Theory and Concepts, Characteristic Features
3. What is the difference between Darwinism and Lamarckism
What is Darwinism
Also known as Darwinian Theory or Theory of Natural Selection, Darwinism is defined as a theory of biological evolution developed by the English naturalist Charles Darwin (1809-1882), explaining a concept where all species of organisms arise and develop through the natural selection of small and inherited variations which increase the ability of an individual to compete, survive, and reproduce. In simpler terms, it is a distinctive form of evolutionary explanation for the history and diversity of life on earth.
The major structures stated in the theory include overproduction, the struggle for existence, variations, survival of the fittest and origin of species. These can be further explained as follows.
- Species are formed by individuals which vary slightly from each other with respect to their several traits.
- Species have a tendency to increase their numbers over generations at a geometric rate.
- This tendency is assessed by the principles of population, limited resources, disease, and predation which will eventually decide the struggle for survival among the members of a particular species.
- Certain individuals will have variations, providing them with a slight advantage in this struggle where individual variations will allow more efficient or better access to resources, greater resistance to disease and a greater success at avoiding predation.
- These individuals will often survive better than others, producing more offsprings.
- Offspring will inherit numerous variations from their parents.
- As a result, favorable variations will be passed more frequently than others and thereby will get preserved over time, and this significant tendency is called ‘Natural ‘
- However, this process will result in a fundamental change in the character of a certain species.
- Over a long period of time, the descendant populations of an ancestor species will differ enough and get classified as a different species with a process of capability along with an indefinite iteration.
- Forces which encourage divergence among descendant populations will be responsible for the elimination of intermediate varieties.
What is Lamarckism
Being the first Theory of Evolution, proposed by Jean Baptiste de Lamarck, a French biologist (1744-1829), Lamarckism is defined as a combination of theories which consist of the inheritance of acquired characters and use and disuse of organs.
In simpler terms, this concept suggests that there is an internal vital force in all organisms with the special consideration of essential needs and desires to produce new structures and change in habits of entire organisms.
Major concepts explained by this theory are as follows.
- Internal Vital Force: All living things and their component parts are continuously increasing in number and size as a result of a pre-existing internal vital force.
- Effect of Environment and New Needs: Environment acts as an influential factor in all types of organisms, and a simple change in the environment tend to make considerable changes in organisms. It also gives rise to new needs which may create new structures and change habits of the organism over a period of time.
- Use and Disuse of Organs: If an organ is used in a constant manner it will tend to develop gradually over time where the disuse of an organ will result in its degeneration.
- Inheritance of Acquired Characters: Individuals acquire characters and features over a lifetime as a result of the internal vital force described above. These will eventually transmit to next generations. This whole process will continue and after several generations, these variations will get accumulated up to a certain extent and create new species.
Example: Evolution of Giraffe
The ancestors of giraffe originally had a small neck and forelimbs and looked quite similar to horses. But since they were living in places without any surface vegetation, they had to stretch their neck and forelimbs to pick leaves to eat, which resulted in a slight elongation of these parts.
However, these beneficial characteristics passed from generation to generation over time and ultimately resulted in a species with a long neck and forelimbs.
Difference Between Darwinism and Lamarckism
Concept
Darwinism: Darwinism suggests that all species of organisms arise and develop through the natural selection of small and inherited variations which increase the ability of an individual to compete, survive, and reproduce.
Lamarckism: Lamarckism is based on new desires which produce new structures and change habits of the organisms over time.
Exceptions
Darwinism: Darwinism does not believe in the internal vital force concept explained in Lamarckism.
Lamarckism: Lamarckism does not accept Darwin’s natural selection theory.
Struggle for Existence & Survival of the Fittest
Darwinism: Struggle for existence and survival of the fittest are two major factors described in Darwinism.
Lamarckism: Struggle for existence and survival of the fittest are not accepted by Lamarckism.
Generations
Darwinism: According to Darwinism, only useful variations will be transferred over successive generations.
Lamarckism: Lamarckism proposes that all the acquired characters are inherited by the next generation.
Image Courtesy:
“Darwin-chart” (Public Domain) via Commons Wikimedia
“Lamarckian evolution” By Solarist – Own work (CC BY 3.0) via Commons Wikimedia
