According to the National Oceanographic and Atmospheric Association, mermaids are not real. In a press release this week, they stated, ""No evidence of aquatic humanoids has ever been found,". Was there really a debate about this? Other than a few 12 year old girls and Eugene Levy's character from Splash, does anyone really believe in mermaids? Mind you, this is a government agency. They are funded by our tax dollars. They used government funds to study whether or not a fictional man/fish existed. I'm pretty sure we could have reduced some government spending right there.
There is an evolutionary theory called the aquatic ape hypothesis. It states that rather than humans evolving from ape-like creatures in Africa 4 million years ago, we actually are descended from dolphin-chimps that crawled out of the sea. Proponents point to certain vestigial traits like the webbing between out fingers and the appendix as evidence. Sounds like BS to me. It's probably just anthropologists that saw The Little Mermaid one too many times.