Question

An example of vestigial organ is:
A. Ear of cow
B. Hair of bear
C. Nail of monkey
D. Nictitating membrane of man

Answer 1

Hint: During the course of evolution, almost every organism has evolved to sustain a better lifestyle. Evolution has taken place in every aspect, either in the case of eating habits, locomotory systems or in the reproductive system.

Complete answer:
The vestigial organs are the organs that have lost their function by evolution in successive generations. These are just present in the body without any function or participation in any event. These organs had their significance in ancestral organisms but not in present day organisms.
For example: the nictitating membrane in man. The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from medial canthus. It is used for protection and moisturization during vision. This membrane is fully formed and found in some reptiles, birds, sharks. In mammals like humans, this membrane is vestigial and is of no use. It remains in the corner of the eye. Some mammals having nictitating membranes are: cats, camels, etc.

Additional information:
Some other vestigial organs found in humans:
> The tail present in the embryonic stage disappears in adults as it fuses to form a tailbone or coccyx in a normal adult.
> Presence of wisdom teeth. Wisdom teeth were present in ancestors as they survived by beating hard substances but later wisdom teeth became vestigial as we now can cook the hard substances into soft ones.
> The appendix is a small pouch attached to the large intestine which is now considered vestigial and does not help in aiding digestion.

Note: Many characters may get diminished when its function becomes harmful, but vestigial organs impose no advantage if these are present and also no disadvantage if not present. Therefore, these are not lost from the body due to natural selection or evolution.