Can science explain vampires and zombies?

Science HeaderIn a previous article (Bloody Perceptions), we saw how transfusing the blood of young mice into old mice could essentially reverse the ageing process and improve the memories of the old mice as well as their ability to learn. The parallels with Bram Stoker’s Dracula are fairly obvious. Stoker, a Trinity graduate, is more responsible than any other person for the myth of the vampire that is so prevalent in our culture today. But are vampires just that: a myth? Given that today is Halloween, I thought I’d look at some scientific explanations for the vampires and zombies that are associated with this time of year.


In 1985, the chemist Dr. David Dolphin proposed somewhat whimsically that the vampire trope might have been inspired by people afflicted with a condition known as porphyria.

Hippocrates is cited as the first person to recognize porphyria which involves the build-up of molecules known as porphyrins in the body. Porphyrins are precursors to haemoglobin, the protein in red blood cells that transports oxygen. When a patient suffers from porphyria their body is incapable of using the porphyrins to make haemoglobin and this results in huge knock-on effects for their health.

Dolphin used the symptoms of porphyria to try to explain certain characteristic features of vampires, namely their pale skin which is sensitive to sunlight, the need to sustain themselves by drinking human blood and their fear of garlic.

Dolphin described how the skin of someone suffering from porphyria is extremely sensitive to sunlight and how the lips and gums recede, so that teeth resemble fangs. The teeth may even glow red due to the deposition of deeply coloured porphyrin molecules.

Dolphin also suggested that garlic contains a chemical that makes the condition worse and that while porphyria can be treated nowadays with an injection of blood products, in the past victims might have instinctively attempted to treat themselves by drinking blood. Dolphin probably meant this as harmless, playful conjecture but it was taken as fact by many members of the press.

To be honest, the connection between porphyria and vampirism is tenuous at best. Victims don’t crave blood, and in any case, ingested blood would be of no help for treatment of the disease since the enzyme necessary to alleviate the symptoms is not absorbed on oral ingestion.

The sensitivity to sunlight is really a modern creation since Stoker’s Dracula was capable of wandering the streets of London during the afternoon. Also, the fact that reported sightings of vampires were so common at the time while porphyria is such a rare condition makes it an unlikely explanation of the folkloric vampire.

Finally, what about the suggestion that garlic worsens the condition?

There is actually a chemical in garlic, allyl disulphide, which can destroy haemoglobin. The argument is that since porphyria victims can’t synthesise haemoglobin properly, garlic would destroy whatever haemoglobin they did have and then their bodies wouldn’t be able to function. However, studies have been done and there is no evidence that porphyria patients have anything to fear from garlic.


It is widely accepted that the legend of the zombie can be traced to Haiti. Haitian folklore has countless tales of corpses being resurrected through the use of voodoo by sorcerers known as bokor. In 1982, Dr. Wade Davis conducted a scientific investigation of the zombie myth in Haiti.

Davis’ interest was piqued when a man named Clairvius Narcisse claimed to have been kept as a zombie slave for almost two decades. Hospital records showed that Narcisse had indeed been reported dead eighteen years earlier. Davis hoped to find that Narcisse’s experience was the result of a drug because he thought that if he could identify the drug then it could potentially be used as a powerful anaesthetic.

Davis found that the bokor used a certain powder to produce the zombie-like state in their victims. Ingredients of the powder included tetrotodoxin. This neurotoxin which is found in pufferfish is known to cause paralysis. Davis proposed that if someone was given this powder then they would temporarily resemble a corpse.

When the effects wore off, it would then appear as if they had returned from the dead. Unfortunately, Davis’ work has faced accusations of not being scientifically valid as the level of tetrodotoxin in the “zombie powder” was found to be lower than he had claimed.

Of course, there are multiple different types of zombies in pop culture now, not all of which follow the tradition of the Haitian zombie. There are fast zombies, slow zombies, robot Nazi zombies, romantic interest zombies and so on. Characteristics that they all tend to have in common, though, include a lack of cognitive control and poor memories.

Neuroscientists Bradley Voytek and Tim Verstynen decided to try to explain these features using their expert knowledge of the brain and its possible pathologies. They suggested that a defunct frontal love would explain why zombies can’t help themselves from trying to devour the brains of the living as the frontal lobe plays an important role in decision-making.

Voytek and Verstynen also drew a connection between the inability of zombies to communicate and a condition known as receptive aphasia. This disorder is caused by damage to the medial temporal lobe and it results in the patient being unable to understand either written or spoken language. While they are capable of speaking, they cannot express themselves meaningfully.

Clearly there has been no shortage of attempts made to provide a scientific explanation for our best loved monsters but with little success. I’ll leave the reader to decide whether they are disappointed or reassured with the knowledge that these creatures remain in the realm of fiction.