explain concept of lamarckism in detail
Answers
Answer:
Explanation:
Lamarckism was proposed by Jean-Baptiste de Monet Lamarck in the year 1744-1829. This theory was based on the principle that all the physical changes occurring in an individual during its lifetime are inherited by its offspring. For eg., the development of an organ when used many times. This theory has been explained here.
Lamarck’s theory includes four main propositions:
1) Change Through Use And Disuse
The organs which are used frequently by the organism develop and the characteristics that are used seldom are lost in the succeeding generations. For eg., a giraffe stretches its neck to eat leaves, a “nervous fluid” would flow in its neck and it enlarges. The organs which the organisms have stopped using would shrink with time.
2) Organisms Driven To Greater Complexity
As the organisms adapted to their surroundings, they became increasingly complex from the simpler forms. Lamarck believed in the spontaneous generation of life.
3) Inheritance of Acquired Characters
An individual acquires certain characteristics during its lifetime. These characters are inherited by their offspring as well. He explained this with an example of a blacksmith. A blacksmith has strong arms due to the nature of their work. He proposed that any children a blacksmith conceives will inherit the development of strong muscles.
4) Effect of Environment and New Needs
The environment influences all the organisms. A slight change in the environment brings about changes in the organisms. This gives rise to new needs which in turn produces new structures and changes the habits of the organisms.
Examples of Lamarckism:
- Evolution of giraffe
- Aquatic Birds with Webbed Toes
- Extinction of Limbs in Snakes
- Flightless Birds
- Cave Dwellers