Question

Differentiate between theories of Lamarck and Darwin.

Answer 1

Lamarck’s theory:

1. According to Lamarck, variations occur in organisms due to environmental changes.
2. These changes involve increased use of some organs and disuse of some other organs.

Darwin’s theory:

1. According to Darwin, variations occur in all individuals of a species.
2. In the struggle of existence, only individuals with useful variations survive and pass these variations on to the next generation.

Difference between theories of Lamarck and Darwin:

Lamarck’s theory	Darwin’s theory
1. It states that variations occur due to changes in the environment.	1. It states that variations occur naturally.
2. All the variations acquired are passed on to the next generation.	2. Only useful variations are passed on to the next generation.
3. The use and disuse of organs bring development and degeneration of those organs.	3. Changes in organs occur due to the appearance of variations in a particular direction.
4. Lamarck’s theory doesn’t consider the struggle for existence.	4. Struggle for existence is a vital part of Darwin’s theory.
5. Example- elongation of giraffe neck to reach higher branches.	5. Example- female peacocks prefer mating with a brightly colored male peacock.