Question

What are the vestigial organs? Give two examples each in human beings and plants.

Answer 1

The word vestigial means remnant of something. It is formed due to evolution.

Complete Answer:
Vestigial organs are the organs that are still present in the body but do not perform any function. They are also termed as useless organs. In ancient times these organs performed important functions in our ancestor’s bodies. They were important according to the old circumstances but due to the course of evolution, these organs are no longer important so they get reduced in size. Vestigial organs are strong evidence in evolution.

Examples of vestigial organs in human beings:
1. vermiform appendix: The appendix is found at a place where the small intestine and large intestine meet. It is said that the appendix is remnants of our herbivore ancestors as they ate nearly all types of vegetations. The appendix was used to digest tough plant material. But because of evolution, humans became selective of what they eat, and over time the appendix started shrinking and became a vestigial organ.

2. Wisdom teeth: Wisdom tooth is the third molar of our dentine (structure and number of teeth). Wisdom teeth were used to chew tough plant parts and raw, rough food. It was very useful to ancient humans as they didn’t know how to cook. The Skull of our ancestors shows that they had big jaws and teeth. Due to evolution, humans learned to produce fire and cook food. Cooked food was easy to chew so our jaw size decreased and wisdom teeth became vestigial. Since our jaw size has decreased, growing wisdom teeth causes a lot of pain since all teeth are not able to fit in.

Examples of vestigial organs in plants:
1 Gynoecium: In asparagus (Shatavari) the gynoecium is vestigial. So, it is called staminode.
2 Androecium: In Cassia (the septic weed) the androecium is a vestigial part. So, it is called pistinode.

Note: Tailbone (coccyx), the nictitating membrane of the eye, extrinsic ear muscles, palmar grasp reflex are also vestigial organs present in human beings. Organs become vestigial because of evolution. According to Darwin, the fittest of all survives, that is the one who adapts faster to the environment survives.