Resurrecting A Dead Idea
As a Science educator, I get asked a bunch of interesting questions by students. Many of them are about standard topics like explosions, space or quantum zeno effects during antimatter hadron collisions. The usual. But by far the most common things I get quizzed about are dreams and death.
Dreams are a tricky one to answer because nobody has a clue what's going on there, so most of the time I have to answer such questions with a shrug. Death, on the other hand, is a really interesting topic and well worth exploring because we actually do have some good knowledge about what happens. Especially the issue kids always want to know about: "could a zombie apocalypse really happen?" It's a question we've all asked ourselves at some point, often while watching the shopping channel, and I addressed it briefly in an article I wrote a while back (here ya go kids).
In that article I focused on what would happen to our infrastructre during such a crisis and how we would survive. Short answer: move to Scandanavia (actually that solves a lot of problems). But at the end of the article I dismissed the whole thing as fanciful because it was basically impossible for zombies to exist. Once you're dead, you're dead.
However, part of being a Scientist is changing your mind when the evidence requires it, and I am happy to say that on the issue of zombification I may need to do just that. Research I've slowly become aware of has made me re-evaluate the whole question and I have come to the conclusion that if you are prepared to be a little generous in your definition of "zombie" then they aren't totally ridiculous.
Which is just as well. The US Department of Health commissioned a report in 2011 on how the CDC might prevent a zombie apocalypse in a paper called ‘The CDC Zombie Initiative’. Originally published as a tongue-in-cheek way of exploring the idea of mass panic, they quickly had to issue a public retraction and apology when people assumed they were proposing a real zombie-outbreak was imminent...ironically causing a mass panic. Now, thanks to this blog, a zombie apocalypse might really be on the cards after all. Hurrah for Science!
The Biology of Death
At a cellular level, death is a simple process. A cell is a bag of chemical reactions so it’s easy to pinpoint when it has died because the reactions change irreversibly, usually accompanied by the outer membrane dissolving and everything leaking out. Once a cell has expired there is no going back, but at the scale of a whole organism it’s harder to define when death occurs because everything shuts down at different rates.
We’ve all heard stories of people who were apparently declared dead by a doctor, only to return to life after a brief intermission. They sound like urban legends but it’s actually a recognised medical phenomenon called Lazarus syndrome. Since 1982, when it was first defined, nearly 40 people have been declared dead by a qualified physician but then decided to make a comeback. The most extreme case being that of 78-year-old Walter Williams from Mississipi, who was registered dead in February of 2014...only to be discovered a few days later by coroners trying to kick his way out of a body bag. Alive and kicking indeed.
Because different organ systems shut-down at different times it can occasionally happen that the main systems go offline, giving the appearance of death, but there can be plenty of chemistry still going on and if the right reactions occur, the whole system can reboot. There are several animals which do precisely that during hibernation after all, including extreme examples like the Alaskan wood fog, Rana Sylvatica, which can survive with two-thirds of its blood frozen solid during winter, before thawing itself back out.
Cells which have truly died can’t be brought back, but new cells can always be regrown (you do it every time you recover from a cold) so it’s possible for parts of an organism to shut down but then rebuild. In fact, according to one research paper published in 2017 by Peter Noble, some cells actually increase their productivity after the body is dead, so even a corpse is still alive in many ways. Death is not clear-cut and can, in some rare cases, be reversed.
We can definitely agree however, that a body eventually reaches a point of no return, even if we can’t say precisely when this point occurs. People have returned from year-long comas but nobody has returned from something like rigor mortis (when the body stiffens up because you are no longer making ATP, the chemical required to break down bridges between muscle fibres). If something fully dies, it’s not possible to bring it back because the cells have burst, but we might be able to justify a zombie apocalypse by picking the right biochemistry to make a person appear to die.
Horrors in the Night
Most people have a fear of death so it’s no surprise that zombies are a common staple of horror stories. Zombies represent the inevitability of death slowly creeping toward us without pause, breaking through our barricades to consume us no matter what we do.
The modern depiction of zombies as shambling corpses seeking the living to eat them alive comes almost entirely from the 1968 movie Night of the Living Dead by George Romero, in which a group of middle-class Pennsylvanians get trapped in a country house under siege by re-animated corpses, originally referred to in the script as "ghouls".
Over the course of six films, Romero invented most of the familiar rules we know today for zombie stories e.g. being bitten will turn you into one, zombies can’t be stopped unless you destroy their brain and they gradually get more rotten as their flesh decays.
Prior to Romero’s hexology of films, zombies were already a well-known monster in folklore but they were just corpses who came back to life, often with their brains in tact. Some of them even ran for government. The Bible itself refers to mass outbreaks of zombies stumbling from their graves and tormenting the living (Zechariah 14:12, Matthew 27:52) as shown in the Fresco below from Notre Dame de Bayeuax Cathedral.
In Romero’s series, it is hinted that the outbreak is caused by a space probe detonating in the atmosphere and showering the ground with radioactive debris. Radioactive material can certainly do icky things to you like make your skin fall off, but it can’t make you impervious to pain and turn you into a cannibal. If we want to legitamise the zombie outbreak we'll have to look somewhere other than 1960s cold war paranoia-infused science fiction...which is always a disappointing sentence.
Taste the Rainbow
The word ‘zombie’ comes from the Haitan word zombi (originally Central-West African) and the folkore of Haiti features tales of people brought back from the dead in a trance to do the bidding of the witch who summoned them.
In 1985 the ethno-botanist Wade Davis even wrote a book about the science of Haitan zombification called The Serpent and the Rainbow, which was adapted into a semi-decent horror movie directed by Wes Craven and starring, of all people, Bill Pullman...whose only other horror credit is freaking Casper.
In The Serpent and the Rainbow, Davis analysed the powder being used by Haitan witches to zombify people and found it to contain a chemical called tetrodotoxin - the active ingredient in puffer-fish poison. Davis claimed this dust would send a victim into a comatose state for a few hours, giving the appearance of death, before they would rise in a hypnotic trance, ready to do the bidding of the witch master.
His results were resoundingly panned by other scientists who tried to repeat the findings but couldn’t because his methodology was so poor. Furthermore, when the powder was analysed by other teams they found it didn’t contain enough tetrodotoxin to even make someone sick, let alone knock them into a coma or put them in a trance (which is not a known tetrodotoxin side-effect anyway).
To give you some idea of how lousy the science in the book is, Davis claims that a witch only had to sprinkle zombi-dust on the road in front of their intended victim to achieve the effect. It sounds like the whole thing had more to do with the power of belief than the power of witches.
If you are raised in a culture that believes ardently in zombification at the hands of a witches, it’s conceivable you might go along with it because of something called ‘the nocebo effect’ - a reverse placebo where you can be convinced you have an illness you don’t really have.
Stranger things have happened. Take the case of Sam Shoeman who was diagnosed with cancer in 1973 and died on schedule according to doctor predictions. It was only at his autopsy that it was discovered his doctors had made a mistake and the tumour was benign. He showed all the appropriate symptoms of slowly dying of cancer, despite not actually having it! Apparently, you can literally talk someone to death. Something I will have to remember for my classes.
Nobody knows how placebos or nocebos work, but our minds are evidently capable of doing things to our bodies through willpower alone. It seems likely to me that so called "witches" are simply telling people they have to act like zombis and the victims just go along with the ritual because they believe they have no choice. So I don’t think we can trigger a genuine zombie apocalypse using puffer-fish. Sorry. Puffer-fish are useless.
What about that guy on the news..
So you may have heard about 'bath salts’ (if you haven't, your kids will have), it's the street drug which hit headlines in 2012 because it reportedly turned people into violent flesh-eaters. Just to make sure we're handling rumour control here, there's no such thing. It's a twisted account of a real event which happened once and once only. This gets a little weird though.
On May 26th 2012, in Miami, a man named Rudy Eugene decided for some reason to attack a homeless man named Ronald Poppo and...eat his face. While holding a Bible. Naked. For eighteen minutes.
Eugene only stopped after being shot five times by a police officer and when he turned out to be a proud Haitan, it was no surprise the press jumped on the story and dubbed him The Miami Zombie.
Police at the time described his relentless and delusional behaviour as consistent with someone taking ‘bath salts’ (a mixture of mephodrone and dimethocaine) and hence bath salts became unofficially known as the ‘zombie drug’ because it made you impervious to pain and susceptible to cannibalism.
However, the toxicology screening of Eugene’s corpse didn’t find any trace of bath salts, only large amounts of cannabis (and large amounts of Ronald Poppo I guess). So I don’t think street drugs are going to give us the zombie apocalypse we’re looking for. I think if we want to come up with a plausible zombie pandemic, it’s going to have to come from the world of infectious diseases.
In the Danny Boyle movie 28 Days Later, the outbreak is started by an engineered super-virus which amplifies the aggression centre of the amygdalae and turns the host into a maniac. Although technically the monsters in 28 Days Later aren’t true zombies because they don’t die and come back, they just go nuts. They also run and zombies are supposed to represent the inevitable onslaught of creeping mortality...we can’t have them being zoom-bies.
I'm going to totally steal their idea however, because it seems to me that it would be the best way of doing it. What we're looking for is some sort of infection which can cause a person to apparently die, before coming back to life as an indestructable flesh-eater on a shulking, rotting rampage.
To start with, there are plenty of diseases which can affect a creature's brain, sometimes in very surprising ways. Consider ophiocordyceps, a breed of fungus which has a disturbing effect on carpenter ants. Once the ants breathe in the spores, it somehow alters their neural chemistry and forces them to abandon whatever they are doing and climb the nearest plant, after which the fungus blasts through their skull, releasing more spores to rain down on the ants below.
This is a parasite which makes its host no longer care about their own safety or other members of their species. It just makes them climb no matter what, forcing them to their own head-exploding doom. If we could propose a comparable fungus for humans that would give us a start. Some sort of fungus which infects the brain and makes the host not care about pain or the well-being of other people. There is no known fungus at present which does this (probably a good thing) but baring in mind we haven't explored something like 90% of our own rainforests, fingers crossed such a human-brain fungus could be out there.
The next thing to study I reckon is lyssavirus, the viral infection which causes rabies. Rabies can be transferred through the bite of an infected host and has an eerily familiar effect on its victims. The symptoms present slightly differently depending on the person, but it usually causes paralysis and apparent death-like symptoms in the early stages, before heightened aggression and violence a few days later.
Thinking about it, perhaps that’s where the original zombie myth came from? The word zombi does originate in Central-West Africa where rabies is common, so maybe that’s where we got the first stories of people who apparently die, then come back and attack us? Zombie myths could be the result of rabies. Rabies doesn’t easily transfer from human to human though, so we’d be talking about an unknown strain which can transfer rapidly, moving to anyone who gets bitten.
If we combine this hypothetical rabies virus with our hypothetical brain-controlling fungus then we might be onto something at last. Contracting a fungal and viral infection simultaneously is pretty rare, although there is one known species of mycovirus (a virus which infects a fungus) which can be transferred to humans called AfuTmV-1. Clearly it’s possible for a fungal infection to hitch a ride with a virus molecule, so let’s say that’s what our zombie pathogen consists of.
Now all we need to do is throw in an aggressive bacteria which can cause necrotising fasciitis - a disease in which the soft tissue of your skin starts rotting while you’re alive, making the infected parts of your body look corpse-like, the so called "flesh eating bacteria" (do NOT google that before a meal). There are quite a few bacteria which do this so let’s propose a variety which spreads in the saliva.
Why I went into Science
So, let’s say that by sheer bad-luck, there is a double epidemic unleashed on the Earth by the powers of fate. A rabies/fungal infection hits first, making all the victims appear dead for a few days before they rise to perpetrate attacks on the living (caused by the rabies). The fungus simultaneously switches off their sense of self-preservation (as it does in ants), meaning infected people will stop at nothing to get food, ignoring all injuries...unless we deactivate their ability to move by destroying the brain.
Then, gosh-darn it, an outbreak of flesh-eating bacteria just happens to hit us as well. All the infected people whose immune systems have been weakened by the rabies-fungus cocktail now end up catching this bacterial inconvenience, making their skin decay as they go after the living. Voila. Zombie-apocalypse achieved. Also, probably the only blog on the internet to feature Disney and Bible references alongisde Motorhead and cannibalism!
I'll be right back, there's some guy in a CDC jacket at my door...
I love science, let me tell you why.