Lamarckism

Explanation

(i) Jean-Baptiste Lamarck proposed that morophological changes occuring in living organisms are responsible for evolution and the reason behind those morphological changes is activities or laziness of that organism.
(ii) The new of giraffe has become too long due to browsing on leaves of tall plants by extending their neck for several generations.
(iii) Shoulders of ironsmith have become very strong due to frequent hammering movements.
(iv) Wings of birds like emu and ostrich have become weak due to no use.
(v) Legs of the birds like swan and duck have become useful for swimming due to living in water.
(vi) Snakes have lost their legs by modification in their body for burrowing habit.
(vii) All these examples are types of acquired characters and are transferred from one generation to another This is called as theory of inheritance of acquired characters or Lamarckism.
(viii) Development of organs due to specific activities or their degeneration due to no use at all was widely accepted but transfer of those characters from generation to generation was rejected.
(ix) Because it had been verified many times that modifications brought in us are not transferred to next generation and thereby Lamarck's theory was disproved.