evidencehistorical
Many mermaid stories likely came from sailors mistaking marine animals like manatees for mermaids.
30% confidence
Sailors in the past who spent long times at sea sometimes saw creatures like manatees or dugongs. These animals have bodies that might look a bit like a human with a tail when seen from a distance, especially in rough ocean conditions. These sightings probably inspired the idea of mermaids in many cultures.
Sources
Mermaid - Wikipedia
Wikipedia
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