Origin and Evolution of Life — BIOLOGY STD 12 Science — Question

1. Vestigial organs are rudimentary organs which are imperfectly developed and non¬functional, degenerate structures.
2. These organs in animals become functionless thus their presence in the body is not required.
3. But they are simply present as they descend down during evolution and continue to exist.
4. In the process of evolution, they may disappear totally.
5. They indicate evolutionary line as they were once functional in the ancestors.

Examples of vestigial organs in human beings:

1. Caecum and vermiform appendix : These are functional in herbivorous animals where they help in cellulose digestion. In humans they are functionless.
2. Nictitating membrane situated in the eyes of humans. It is a remnant of third eyelid.
3. Coccyx or tail vertebrae which shows remnant of tail, Wisdom teeth or 3rd molars. These organs indicate that human beings descended from ape like ancestors.