Explain the occurrence of vestigial organs on the basis of Lamarck's theory of use and disuse.
Organs which are found in reduced or rudimentary condition and do not perform any function in the possessor are called vestigial organs or non-functional organs. They help in understanding the history of evolution and continuity of life.
- Wisdom teeth: They are the last molars which appear last at the age of 17-20 years.
- Vermiform appendix: It projects from the blind end of the caecum and is a functionless organ in humans. It is helpful in herbivorous mammals.
- Pinna: It is the lobe-like part of the external ear which humans cannot move as in other mammals. As it is poorly developed, it is a vestigial organ.