Question

What do you understand by the term natural selection? Write Darwin's theory of evolution.

Answer 1

• Natural selection means that the organisms with favorable variations will survive because they adapt to the changes in their surroundings while the unfit organisms (who do not adapt to the environment) will be destroyed or eliminated by nature.
  
• Darwin in 1839 gave the theory of natural selection.
  
• According to his theory, as a struggle for existence only those organisms could survive which had favourable variations to adapt with the surrounding environmental conditions or the population conditions. In simple words, the struggle for existence results in the survival of fittest which means that natural selection favors those organisms which are most fit to survive in the environment and produce the offspring.
  
• Example: according to Darwin's theory of natural selection is the size of the neck and legs in Giraffes. He stated that in the ancient times, both long neck and long legs and short neck and short legs giraffes were present. Due to the scarcity of grass on the land, the giraffes had to feed on the leaves of tall trees. Hence, giraffes with long necks and long legs could get the food easily. So, they had a better chance of survival. Therefore giraffes with long neck and legs became abundant and those who had short neck and legs became extinct.