Have you ever seen a mermaid? Are they a subject for cryptozoologists or for psychologists? We go diving for pearls of wisdom.

Half-woman, half-fish, the mermaid is an integral part of our cultural psyche. Adverts, films and cartoons depict friendly, beautiful women living happy lives under the sea and yet having a huge fascination with humans. Older tales are darker and more adult with themes of sacrifice and repressed sexuality. Are mermaids just a psychological archetype, a children's bedtime story, or are they real, flesh and blood creatures of the deep? With 70% of the Earth's surface covered in water and vast deep sea areas left unexplored, could mermaids simply be a creature that has not been discovered, catalogued and authenticated by humans?

The science bit
The scientists think not. While several marine biologists were horrified at even the thought of an interview on the subject, we got the accepted view from the very charming and down-to-earth Professor Monty Priede, professor of zoology and head of Oceanlab at Aberdeen University .

"The classic picture is of a mermaid as being half female and half fish but as to combining a mammal with a fish, they are a long way apart in terms of the evolution of vertebrates. The popular theory is that the manatee or sea cow is the nearest representation of mermaids. These are found in coastal regions and have a fish-like tail but are certainly not beautiful. It may be that mariners having been at sea for a year or two might be hallucinating. The nutrition also used to be quite poor on sea voyages in those days and vitamin deficiencies induced psychological conditions that could cause them to perceive sea mammals as beautiful women."

On the argument that the lack of complete knowledge about Earth's oceans could mean that mermaids have just not been discovered yet, he says: "I don't think the famous example of coelacanth [prehistoric fish thought to be extinct] found in West Africa and South East Asia in the 1990s counts here in the same way. While we certainly haven't discovered all the animals in the world, one point to consider is that the deep sea is not a repository of ancient animals. The modern deep sea has only been habitable relatively recently in geological terms."

So is there conclusive proof that the mermaids of myth and legend do not exist?

"In Homer's Odyssey sirens tempt sailors to shore, The Mediterranean almost dried out 10 million years ago and then refilled relatively recently in the evolution of man. In the early Homer references the Mediterranean was as dry as a desert. Ancient Western stories from the Mediterranean cannot have a possibility of a real animal in that area, hung over from ancient times."

However the interesting fact remains that mermaids are not just based in stories around the Mediterranean , they abound in legends all around the world. They seem to be a part of our collective memory. The first recorded mention of part fish, part human creatures is with the ancient Babylonian belief in the God Oannes, Lord of the Waters. Indeed mermaids, in this way, form the basis of not only cultural beliefs but also some religious beliefs. West African religions such as Vodou believe in Mami Wata, a goddess of the sea who appears in mermaid shape. Mami Wata is kind to women, often blessing them with children but her especial sympathies lie with barren women.

Female pain
There seems to a particular link between real life human women and mythical mermaids. The many tales of the painful process that mermaids have to go through to become human tie in to the uniquely female pain of menstruation and childbirth. In the Hans Christian Anderson (rather than the Disney) version of the tale, the little mermaid first has to bear the pain of eight oysters attached painfully to her tail at the age of 15 to denote her rank and that she has come of age. Then when the sea-witch grants her wishto be human, she suffers the 'double-edged sword' pain of her tail turning to legs. Then subsequently each step she takes feels like she is walking on needles or swords.

In this way the fish tail can be seen to be symbolic of the female reproductive system. The tale of Melusine, the enchanted serpent or fish-tailed wife of Raymond of Lusignan speaks of how Melusine forbade Raymond to see her on Saturday nights, when her lower half would be transformed into that of a fish-serpent. This secrecy from men of the transformative powers of women and the fact that Melusine's condition is the result of a curse from her mother can be seen to have parallels in the very real condition of menstruation, often refered to as 'the curse'.

So are these symbolic, psychological aspects another argument for saying that real mermaids do not exist and are just a way for us to make sense of the world around us? Perhaps, but we should not discount the similarity of disparate accounts of the mermaid myth. Nor its pervasiveness throughout so many different cultures.

Lighthouses
Mermaid sightings are believed to be ill omens, foretelling bad storms, rough seas and death at sea. There are numerous folk tales and sightings (see box opposite) that show that it is not just as portents of death that mermaids appear. Indeed it may be that these creatures are akin to lighthouses, warning sailors of danger so that they can avoid it as opposed to seducing them toward a watery grave. They are also said to have the rather positive faery power to grant wishes.

For those wishing to go mermaid spotting, good places for a holiday this summer would be coastal regions such as Cornwall and the Northern Isles of Scotland. Other freshwater varieties are said to be found in rivers and pools, such as Mermaids Pool below Kinder Downfall in Derbyshire and Black Mere, near Leek in Staffordshire. At the end of the day, whether mermaids are real or not seems to be the same judgement call we all have to make about weirder things like quantum physics. It is said that if you can imagine it, then on some level, in some dimension, in some universe, it is very much real.