According to Lamarck’s theory of evolution, the early male giraffe had a shorter neck and front legs than a horse. They eat grass and leaves of small plants. Due to various reasons, the amount of grass on the ground decreases and then they start eating the leaves and branches of tall trees. Later it starts eating the leaves of higher trees. In this way, the giraffe’s neck becomes longer due to eating the leaves of tall trees. It is the nervous system of the giraffe that makes it eat leaves with its neck raised. Giraffe’s neck lengthened according to his wishes and needs. Later, the length of the neck increased with each other. Modern long-necked giraffes evolved from short-necked ancestors. The topic of Lamarckism in the evolution of Giraffe is-
(i) Under the influence of endogenous forces organisms can cause growth of their organs.
(ii) Environment has a direct effect on organisms.
(iii) Development of any organ of an organism depends on its use and disuse.
(iv) Acquired qualities of organisms are transmitted from generation to generation.