Horror taps into deep fears and anxieties by telling a story of unnatural powerful monsters that plague our normal lives. To work, though, the fantasy has to connect with our ordinary experience, which is the place where real world science overlaps with monsters, vampires, and werewolves of our nightmares.
Frankenstein and the Reanimation of Dead Tissue
Biotechnology, by definition, is the technology of life and what classic horror story comes closer to capturing this theme than the Frankenstein monster? Transforming dead tissue to into a living organism is clearly a biotechnology project. Of course, reanimating a fully formed human is a bit ambitious as an initial experiment, but hey, it worked.
The biotechnology in Frankenstein is based on the theory that electricity is what animates tissue—it is the life force in animals. This idea seemed to start with Luigi Galvani who found that frog legs would contract when touched with electrostatically charged metal. He explained this response by suggesting that muscle and nerve fibers must be able to produce electricity by accumulating positive and negative charges on two opposite surfaces. He also postulated fluid-filled pores to carry the current between the two surfaces. He actually wasn't too far off.
Luigi Galvani was forced out of his position at the School of Bologna which ended his career. However, his nephew, Giovanni Aldini, followed up on his uncle's experiments and gave demonstrations around Europe applying electric currents to dismembered bodies of animals and humans (sound familiar?). Giovanni began looking for therapeutic applications for his work, and it eventually became the basis of electroconvulsive therapy (aka., electroshock treatment) for mental disorders.In fact, nerve cells do work by altering an electric charge across their membranes. They maintain an excess of sodium ions outside and potassium ions inside. In response to a stimulus, channels open in the membrane to let the sodium enter which creates an electric impulse. Although Luigi Galvani knew nothing about cells, his explanation was pretty close.
Although some pseudoscience proponents that attribute neural electrical impulses with mystical properties or equate them to Eastern religious concepts of chi and prana may disagree, bioelectricity is chemically produced by cell membranes and sodium channel pumps. While a fascinating reaction, it's the result of life's chemistry, not the source.
Vampires, Blood, Youth, and Disease.
Blood is the vital fluid in our bodies. We require about 5 quarts or so to function. In societies that don't know anything about cells, DNA, and proteins blood is the obvious special ingredient for life.
According to the bible "the life of the flesh is in the blood" (Lev. 17:11), and, according to Dracula, "The blood is the life." It was believed to be the essence of life and sucking the blood from someone is equivalent to sucking their life. Traditional vampires (not modern day ones like Twilight's brooding Edward and the rest of the Cullen's) are harbingers of disease and death.
Blood is essential for larger animals. It provides nutrients and oxygen to the billions of cells in the body of larger animals. In fact, though, blood chemistry is very complex. It contains all sorts of factors, hormones, proteins, and different types of cells. For ages blood has been thought to be the secret to longevity. It is claimed Hungarian countess Elizabeth Bathory bathed in the blood of young girls in an attempt to remain young, and may have drank it too. Former Korean dictator Kim Jong-Il was also rumored to have himself injected with the blood of young women for similar reasons. Recently, beauty treatments have picked up this theme too and reinject purified components from a person's own blood into their face.
While the rejuvenation powers of blood are old idea, science has shown some evidence that blood may, in fact, contain some anti-aging secrets. It was recently found that, when blood in old mice is replaced with blood taken from young mice, it appears to reverse some signs of aging in the mice. It is not clear what components in the blood are responsible.
Although very common, blood is an exceptionally complex unique fluid that is still not completely understood. It regulates the body's chemistry and physiology. Blood tests provide the main diagnostics medicine and there is active research to develop blood tests to identify the presence of cancer, Alzheimer's disease, and a host of other diseases. Maternal blood has even been used for genetic analysis of the fetus. While each cell is its own chemical reaction, the combined chemistry of the billions of cells in our bodies—the chemisty of us—is in the blood. Maybe it's not surprising that it is often attributed with mystical properties.
The Legend of the Werewolf
Shapeshifting is obviously beyond the human body's capability. Human development itself is an amazing metamorphosis from a single egg to human baby to aged adult, but it takes time. While certain disorders and diseases can create exaggerated or grotesque morphology such as the "elephant man" Joseph Merrick or Roy Lee Denny, the subject of the movie Mask, there are no mechanisms for rapid reversible changes in structure.
However, the origins of the werewolf legends probably didn't develop to explain people turning into wolves, but to explain actions of psychotic killers and sociopaths. In other words, they have less to do with people changing into an animal and more about people acting like a savage animals. It is certainly easier to think of Jeffery Dahmer and Ted Bundy as animals than humans.
There are diseases that may have embellished the myth, however. For example, the genetic disease hypertrichosis can produce wolf-like hairiness on the face that body. Despite the superficial resemblance to the classic werewolf with hypertrichosis, rabies may be an even stronger model for the werewolf myth. After all, rabies is a virus transmitted by the bite of an animal that attacks the central nervous system and causes people to become very anxious, excitable, drooling, and mad, in the classic sense of out of their minds. That all tracks pretty closely to the werewolf legend.
One of the most interesting scenarios, though, that may have advanced the werewolf legend, and possibly belief in witches too, has been put forth by historian Mary Kilbourne Matossian. She correlated medieval werewolf and witch trials with conditions suitable to for the growth of ergot, a rye fungus that contains an hallucinogen related to LSD. The European poor ate a lot of rye bread and, it seems that, when conditions were optimal for the fungus in a region, many more people were tried for being werewolves and witches. Hallucinating peasants, it seems, saw a lot more witches and werewolves.