What are Vestigial organs? Give one example of a vestigial structure in the human mouth.
Topic: Vestigial organs
Answer
VESTIGIAL ORGANS are organs that are REDUCED IN SIZE and NON-FUNCTIONAL in an organism, but were well developed and functional in its ancestors.
Example in the human mouth: the WISDOM TEETH (third molars).
One mark for the definition, one for the example.
The definition must contain BOTH halves: useless NOW, but FUNCTIONAL IN ANCESTORS. Saying only "an organ of no use" misses the evolutionary point, which is the whole reason vestigial organs are studied.
WHY WISDOM TEETH: our ancestors ate raw, coarse, uncooked food and needed a large grinding surface and a bigger jaw. With cooking, the jaw became smaller while the teeth did not reduce as fast — which is why wisdom teeth now often have no room and must be extracted.
Other human vestigial organs, useful for a different question: the vermiform appendix, the coccyx (tail bone), the nictitating membrane in the eye, body hair and the ear muscles.
They are important EVIDENCE FOR EVOLUTION: a structure that is useless now but useful in a related animal shows common ancestry.