Analysis: here's how science can help explain how various vampire legends have developed

Stories about blood-sucking creatures of the night have existed in various cultures for thousands of years. However, the vampire mythology we are familiar with now has been mostly established since the 1600s, with countless books, films, songs and TV shows helping to stake the vampire's claim as the most popular horror icon of the last century. Here we look at how science can help explain how various vampire legends developed.

Life beyond the grave

In 17th and 18th century Europe, regular outbreaks of disease like plague, cholera and tuberculosis decimated many communities across the continent. Depending on the cause of death and method of burial, corpses took on different appearances. Some appeared bloated and red, others displayed blood stains at the mouth, and those buried in cold, dry climates appeared surprisingly well-preserved.

Nowadays, we recognise these observations as normal pathological processes of bodily decay. But our ancestors turned to supernatural explanations and concluded some of the dead were rising from their graves at night to feast upon victims and spread disease further. Indeed, the word Nosferatu is believed to derive from the Greek word 'nosophoros' meaning ‘disease-bearing’.

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Thus, bodies of individuals suspected of being a vampire were often exhumed so that a stake could be driven into their chest. On freshly buried corpses, this released both bodily gases and liquefied organs, often with accompanying ‘groans’ which only served to convince onlookers of their vampiric nature. For good measure, corpses were often decapitated and ritually burned as well. All these superstitions and practices merged over time into vampire folklore which was subsequently carried to the New World.

Death by sunlight

Rare diseases characterised by severe sensitivity to sunlight are also likely to have contributed to vampire myths. Porphyrias are a group of blood disorders caused by abnormalities in the production of heme, an important component of haemoglobin, the molecule which carries oxygen in red blood cells. These abnormalities cause a build-up of toxic metabolites called porphyrins in the body, including in skin cells.

Porphyrins are highly reactive to UV light, so sunlight can cause blisters and burns on exposed skin. Furthermore, porphyrins excreted in urine turn it a red-purple colour, so porphyria sufferers were suspected of drinking blood. In some forms of the disease, the gums recede and the porphyrins leach into the teeth, giving sufferers the appearance of blood-stained fangs. Significantly, the disease is known to have been prevalent in Eastern Europe, where much vampire mythology began.

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Xeroderma Pigmentosum (XP) is another photosensitive genetic disorder. XP sufferers cannot repair DNA damage in skin cells caused by UV rays, resulting in severe sunburn upon exposure to sunlight. As a result, they have an increased risk of developing skin cancer and a reduced life expectancy. Nowadays, XP sufferers can benefit from protective clothing and supportive communities, such as Camp Sundown which help cater to the needs of so-called 'Moon Children'. But in the past, these unfortunate people would have been forced to live a largely nocturnal existence, which would have aroused suspicion that they were vampires.

Release the bats!

Yet another disease explains why bats became linked with vampires. Rabies is a deadly disease often spread to humans by a bite from an infected bat. It is caused by a virus which affects the nervous system, causing sufferers to experience muscle spasms, hallucinations and aggressive behaviour. Notably, many rabies victims are compelled to bite others, thereby ensuring effective spread of the virus.

Again, people turned to supernatural causes to explain these incidences and it became accepted that vampires were shapeshifting creatures who could turn into bats and other disease-carrying animals, such as rats and wolves. However, vampire bats rarely bite humans, preferring instead to feast quietly upon the blood of sleeping animals, like livestock. Cleverly, vampire bat saliva contains a natural anticoagulant which prevents the animal's blood from clotting as they feed. Scientists call this molecule 'draculin’ and are studying it to help them develop new medicines which can dissolve clots and be used to treat stroke victims.

From National Geographic Wild, the world's weirdest vampire bats

The blood is the life

As we know, vampires are immortal, as long as they have blood to sustain their eternal life. However, the idea that fresh blood can restore health and vitality to sick bodies not unique to fiction. Every day, life-saving blood transfusions are carried out in hospitals worldwide, using compatible donor blood to treat patients. Likewise, remarkable advances in bone marrow transplants and stem cell therapy are based on the concept that healthy blood cells can replace diseased blood cells to cure disorders like leukaemia.

In cosmetic surgery, the controversial 'vampire facial' procedure extracts platelets and growth factors from blood and injects them into the face, which supposedly rejuvenates the skin. Most recently, the medical response to the ongoing coronavirus pandemic has included instances where blood from those who survived Covid-19 can successfully treat others who have been infected. So, while vampires may rely upon new blood to live, the same is true of many humans.

How to keep vampires at bay

Methods for warding off vampires are often rooted in the use of natural remedies for infection. Garlic has been used to treat illness for thousands of years and was often placed in the mouth of corpses to prevent spread of disease. Garlic contains several components which have medicinal properties, including allicin, which has been shown to kill a wide range of bacteria, fungi, viruses and several parasites.

READ: What was behind the Irish grá for garlic as a folk cure?

READ: Death, sex, superstition and fear: the hawthorn tree in Ireland

READ: Was Dracula Irish?

Other plants reported to repel vampires include rose, blackthorn and juniper, which all contain antimicrobial compounds. Prospective vampire-hunters are advised to make their wooden stakes from hawthorn, the extracts of which have potential for the treatment of cardiovascular disease.

Finally, a scattering of mustard seeds may help, not just for their antibacterial qualities, but because a vampire will be compelled to stop and count the seeds. This obsessive compulsion to count things is a lesser known trait of vampires, but it would certainly explain the behaviour of Count von Count on Sesame Street!

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Anyway, hope all this is useful in case you meet a real vampire this Halloween. I must go now as there's a gentleman at my front door who won’t come in until he’s invited. Nice to see some people still have good manners these days.

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