Science Advocacy
Science Advocacy
Vampires and zombies and werewolves, oh my! Halloween is upon us, and it’s time to get creepy!
Imagine a world like Sam and Dean’s Supernatural: where every monster, every soul-sucking, flesh-eating creature, every undead lurker you heard about in the shadows of the campfire actually existed. Except, instead of being sustained by magic, it was all scientific! How would that be possible? Let’s have a little fun today and talk about the science behind a few Halloween favorites.
No Halloween-themed movie marathon is complete without a good zombie movie. Zombies are one of the few spooky creatures that have made their way into our regular world, with widely popular shows like The Walking Dead, big-budget films like World War Z, and countless zombie-slaying video games putting the spotlight on everyone’s favorite undead mythical beastie. Zombies are the current figureheads of the creepy creatures club, and there are several interpretations of just what a zombie is: they can be fast or slow, smart or stupid, graceful or clumsy. But in nearly all zombie adaptations, they are undead, flesh-eating, formerly human monsters. How can this happen in a scientific world?
Most fictional zombie apocalypses happen through a “sounded good at the time” situation where some sort of infectious agent – things like viruses, bacteria, and prions – is mutated for some sort of broad purpose, such as biological warfare, medical progress, or just for funsies (because we all know Hollywood scientists have no moral compass). But the question is, in a real world scenario, would it be possible to create an agent that efficiently infected, killed, and reanimated the host, producing an actual undead zombie?
The short answer – no. Once something is dead, it’s dead. Zombies may be stupid, but they still require at least a partially functioning cerebellum for motor control, and the cerebellum can’t function without blood flow and working ion channels, which facilitate the nerve impulses that allow for movement. But ret not, zombie apocalypse enthusiasts! There are several infectious agents out there that could potentially produce a “living” zombie, so to speak.
Prions are often discussed as one of the more likely potential zombifying agents. Prions are infectious proteins that cause normal proteins to fold incorrectly. Prion diseases usually target the brain, often causing rapid, severe damage (by basically making holes in the brain), and there is no cure for them. The only caveat – prion diseases usually require a long incubation time (often years) and are NOT very efficient infectious agents, but the solution could be as simple as attaching the prion to a highly infectious virus (say, the rabies virus), and BAM you’ve got a zombie apocalypse.
There are also certain species of fungi, such as Ophiocordyceps unilateralis, that are known to “zombify” insects by literally controlling their nervous system through various secretions. O. unilateralis can wreak havoc on ant colonies by infecting ants, inducing their behavioral changes that cause the ants to leave the colony and travel to an area where the pathogenic fungus can grow, eventually killing their hosts when the fungal fruiting bodies burst through the ant’s head. Terrifying, right? Good thing this particular fungus doesn’t affect mammals. For now…
Then there are viruses that target the brain, such as the rabies virus, which have realistic potential to create zombie-like creatures. CRISPR-Cas9 gene editing technology is already being used to create cancer-killing viruses (Yuan et al. 2016), which, if I remember correctly, sounds eerily similar to the plot of I Am Legend…
Essentially the “fancy” zombies of the horror universe, vampires are one of the oldest mythical creatures of the dark. They have ancient roots in folklore, their origin is unclear, and there are several variations of vampires around the world. There are no consensus characteristics which make a vampire, but in most myths, vampires are creatures affected by “vampirism,” which is a condition that causes an insatiable thirst for blood along with a variety of other side effects such as a state of un-death or immortality, the ability to turn into bats, a repulsion by religious symbols and garlic, and the inability to tolerate sunlight (with the exception of those lame shiny vampires from Twilight). Scientifically, how could a vampire exist in real life?
Just like with zombies, there isn’t exactly a realistic possibility of a sentient undead being roaming around preying on innocent people. However, there are quite a few existing organisms that do require the blood of other creatures to survive – the most relevant (and appropriately named) of these being the vampire bat. Vampire bats are hematophagous, meaning that blood is their source of food. Hematophagy is incredibly uncommon among mammals because blood is a very costly, inefficient source of nutrition, and vampire bats are actually the only mammals that have evolved to use blood as their sole food source (Delsuc and Douzery). Vampire bats have to consume 50-100% of their body weight in blood every night or they will die of starvation within 48 hours (Wilkinson 1990), and they only feed in complete darkness (Crespo et al. 1972). There are three species of vampire bat and they are all native to the Americas.
They prefer to feed on livestock in tropical areas – so, hide yo cows, hide yo goats, and hide yo horses, because they’re feeding on everyone up in here!
Although vampire bats certainly aren’t as terrifying as the famous Count Dracula, there are many parallels to be drawn between these unique creatures and the vampire lore, and vampire bats are probably the closest thing to a real vampire in our world. And, who knows, if the vampire bats managed to evolve a blood-lapping lifestyle – maybe we’ll see some hematophagic humans in a few million years as well!
Werewolves, enemy to vampires and a Halloween trademark, are humans affected by “lycanthropy,” an affliction that causes an uncontrollable transformation into a wolf (or wolf hybrid) when there is a full moon. In some modern representations of werewolves, a full moon is not necessary, and a werewolf can transform at will or if they lose control of their emotions. In either interpretation, werewolves are a sort of human-wolf hybrid creature that may or may not be dangerous – it really depends on your interpretation of werewolves!
Scientifically, hybrids animals do exist (e.g. ligers and mules), but the creation of a hybrid requires two closely related species. Similar to hybrids are chimeras, which are organisms that contain cells from two different complete sets of DNA. Chimeras simultaneously express characteristics from both sets of DNA, and are extremely valuable in scientific research – scientists have been creating and using rodent chimeras for decades to study gene function.
Japanese scientists recently succeeded in creating pig-human chimeric embryos (Wu et al. 2017). This paper was published in Cell earlier this year, and is extremely controversial. Although the method is nowhere near perfect enough to create a viable chimera, with rapidly developing DNA technology, the ability to create human-animal chimeras is certainly within our reach. Creating a werewolf would be difficult (not to mention wildly unethical), as humans and wolves are not closely related and have very different developmental processes, which might prove an impossible hurdle to overcome using current methods. However, with a little time, and a mad scientist….who knows what could happen?
