Evidences Of Evolution

Homologous organs are structures that share a common basic anatomical plan and developmental origin because they are inherited from a common ancestor, even though they may perform different functions in different species. The forelimbs of a whale (swimming), a bat (flying), and a human (grasping) all contain the same set of bones, humerus, radius, ulna, carpals, metacarpals, and phalanges, arranged in the same pattern, reflecting divergent evolution from a shared ancestral limb. Analogous organs are incorrect because they have different structural origins but similar functions, such as the wings of insects and birds, illustrating convergent evolution rather than common ancestry. Vestigial organs are reduced, functionless remnants like the human appendix and do not describe full functional forelimbs. Atavistic organs refer to the reappearance of ancestral features, which is unrelated to the shared limb plan described. As detailed in NCERT Class 12, Chapter 7 (Evolution), homology provides anatomical evidence for divergent evolution from common ancestors. As a logical check, similarity in underlying structure despite different functions is the defining signature of homologous organs, confirming the answer.