Question

What is the main theory of evolution?

Answer 1

Evolution :

1. Evolution is a kind of theory that describes the changes in the traits of a species of plants, animals, and other living things over generations.
2. The main theory of evolution is Darwinism.
3. Darwinism is the theory of natural selection that was given by Charles Darwin and is considered the main theory of evolution.

Postulates of Darwinism :

Geometric increase :

1. According to Darwin the population size tend to increase geometrically i.e. (doubles after a certain period).
2. For example, Paramecium divides three times by binary fission during favorable conditions in 24 hours.

Struggle for existence:

1. Darwinism states that due to rapid multiplication the size of the population increases.
2. But due to limited food and space, the organisms living in a population start competing with other organisms in the population.

Natural selection:

1. This theory states that nature selects the individuals out of the population who are fit (with useful variations and are best adapted to the environment) and the unfit individuals are rejected.
2. This postulate is also termed survival of the fittest, the nature selects the fittest organism while the unfit organisms are rejected by nature.