Vestigial Structure
흔적기관
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<speciesfyi-glossary slug="vestigial-structure"></speciesfyi-glossary>Definition
A reduced or functionless body part that was fully developed and functional in an organism's ancestors.
Detailed Explanation
Vestigial structures provide compelling evidence for evolution — they make no sense unless an organism shares ancestry with forms that had functional versions. Human embryos develop gill pouches that later transform into jaw and ear structures. The human coccyx reflects our tailed ancestors. Vestigial eyes in cave fish still develop but degenerate, showing evolution is gradual and path-dependent rather than perfectly optimizing.