The roots of mermaid mythology are more complicating than one would expect. In modern myth, we tend to see mermaids in a singular way - kind and benevolent to humans who keep to their own kind in the deep waters of the ocean. Not all stories go this way, though, and in most cases, the most ancient tales of mermaid mythology follow quite a different view.

The earliest known mermaid legends come from Syria around 1000 B.C. where the Syrian goddess, Atargatis, dove into a lake to take the form of a fish, but the powers there would not allow her to give up her great beauty, so only her bottom half became a fish and she kept her top half in human form.

Later tales in the mythology of mermaids come from Homer's epic "The Odyssey", where some mythologists believe the Sirens to have been in mermaid form. This was an extremely popular version of the mermaid throughout history. 

The evil-intentioned mermaid is not the only way these creatures were seen as dangerous. Some believed that even well-intentioned mermaids would cause great danger to men who believed they saw a woman drowning and would dive into the waters to save them. Other tales suggest that mermaids either forgot or didn't understand that humans could not breathe underwater, and they would pull them down into the depths of the sea, accidentally drowning them in the process.

In the modern mythology of mermaids, however, this is rarely the case. Today, these beings are more likely to be seen as innocent and sweet, if not helpful in many cases to human kind. Much of the modern interpretation of mermaids can be credited to the most famous tale in all of mermaid mythology, "The Little Mermaid".