Question

What is being shown in the following diagram?

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.
3. These acquired changes are then passed on to the next generation.
4. The above diagram shows the evolution of the giraffe from short neck to long neck and forelimbs which is an example of Lamarck’s theory.

Use of organs:

1. According to Lamarck, extensively used organs grow in size and become stronger with each passing generation.
2. The ancestors of giraffes were ground-feeding herbivores. When the ground vegetation became scarce, the ancestors of giraffes stretched their necks and forelimbs to obtain food from lower branches of trees.
3. The above process continued for several generations and resulted in the formation of longer forelimbs and necks. The longer-necked giraffes could easily reach the leaves of medium trees.