Analysis: let's take a look at some real medical conditions which have helped to shape the traditions and rules of werewolf mythology

It's Halloween again, meaning creatures of the night will once more take to the streets in their unquenchable quest for human victims and fizzy sweets. Sightings of werewolves will be common, evidence of an enduring human fascination with lupine creatures (from the Latin word 'lupus’, meaning "wolf").

Throughout history, the wolf has featured prominently in the folklore and legends of many cultures across the world. Sometimes wolves are depicted in a positive manner, such as the ones who raised lost children like Cormac mac Airt, Romulus & Remus and Mowgli. More often, however, they are presented as a symbol of evil, reflecting a natural human fear of the wolf as a dangerous predator to be kept from the door. Hence, fictional wolves became synonymous with deceitfulness and destruction, not least in several fairy-tales which feature a Big Bad Wolf as the villain.

These stories also included accounts of humans being transformed into wolves, most notably King Lycaon in Greek mythology, who received this punishment for attempting to trick the god Zeus. Ever since, the werewolf (from the Old English word "wer", meaning "man") or lycanthrope (from the Greek word "lykos", meaning "wolf") has become embedded in mythology as a shapeshifter character. More recently, the werewolf has been popularized as a horror icon in film, TV, literature and music, all of which have collectively established the werewolf characteristics we are familiar with.

However, it is interesting to consider some real medical conditions which have helped to shape the traditions and rules of werewolf mythology.


Hypertrichosis is a medical condition which results in excessive body hair growth on different parts of the body. Although it is rare, there have been several notable cases throughout history, including Fedor Jeftichew and Annie Jones who became famous as 'Jo-Jo the Dog-faced Man' and ‘The Bearded Lady’ respectively in PT Barnum’s travelling circus.

In recent times, the best known and studied cases are the Wolf Family of Mexico, several of whom suffer from an inherited congenital form of hypertrichosis. Genetic analysis of their DNA has identified shared abnormalities on the X chromosome which affects genes which can control hair growth. Similar research on other affected individuals identified other genes that can cause the condition.

BBC News report on the wolf family of Mexico, several of whom suffer from an inherited congenital form of hypertrichosis

Scientists propose that these genes were gradually switched off as humans evolved from ape-like creatures, resulting in less body hair. Somehow, these have been reactivated in congenital hypertrichosis sufferers, but the exact mechanism remains unclear.


Rabies is a deadly disease typically transmitted to humans by a bite from an infected animal, such as a rabid dog. Rabies is caused by a virus carried in saliva which targets cells in the brain and central nervous system. As these cells become increasingly infected, sufferers begin to exhibit aggressive behaviour, develop muscle spasms, experience hallucinations and produce excess saliva, causing frothing at the mouth. The similarities between these symptoms and the stages of werewolf transformation are evident.

Likewise, the idea of lycanthropy as an infection contracted from the bite of another werewolf seems likely to have its origin in the way rabies spreads to humans. Without medical knowledge, it is easy to see how our ancestors would have turned to supernatural explanations for this transmissible animal "curse".

A brief history of werewolf mythology

Clinical lycanthropy

Clinical lycanthropy is a recognised psychological disorder in which sufferers believe they are becoming a wolf and behave accordingly. It is a very rare condition that can be classified as a Delusional Misidentification Syndrome (DMS), a group of neurological illnesses in which patients perceive dramatic changes in the appearance of people or places.

Recent evidence from DMS studies suggest the cause lies in an area of the brain concerned with self-recognition and perception of one's own body. For example, neuro-imaging of individuals diagnosed with clinical lycanthropy showed this region of the brain displayed abnormal neuronal activity, which seemed to cause the delusions about their physical appearance. Despite these advances, it is still a poorly understood disorder, although the psychiatric therapy administered nowadays represents progress from lycanthropy treatment in the Middle Ages, when sufferers were presumed to be possessed by the devil and were therefore burnt at the stake.

Poster for 1961's The Curse Of The Werewolf. Photo: LMPC via Getty Images


Although parents of teenagers may disagree, puberty is not generally considered a medical disorder. Nevertheless, werewolf myths have proven a ripe metaphor for the changes associated with adolescence, including aggressive behaviour, heightened sexual emotions, muscle development and emerging body hair.

Furthermore, parallels between the lunar cycle of the werewolf and the onset of the monthly menstrual cycle has often been used to add symbolic subtext to tales of female werewolves. Little wonder that werewolves remain so appealing for teenage horror fans!

Poster for 1957's I Was A Teenage Werewolf


Various other snippets of science underpin other werewolf myths. As Harry Potter fans will know, Harry's teacher Remus Lupin (note the name) used Wolfsbane Potion to keep his lycanthropy under control. Wolfsbane is in fact a very poisonous plant which was used by people throughout history to kill nuisance animals, including wolves.

Elsewhere, the idea that a silver bullet can kill a werewolf is likely related to the anti-bacterial properties of silver as an element. And the super-human strength or speed exhibited by werewolves is probably just a simple reflection of the remarkable endurance and tracking ability of wolves in inhospitable environments.

So it seems unlikely you will encounter a real werewolf this Halloween. But, just in case, best stay on the road and keep clear of the moors. And beware of the moon

The views expressed here are those of the author and do not represent or reflect the views of RTÉ