5 Reality-Based Ways to Start a Zombie Apocalypse

Have you ever watched a zombie movie where the outbreak's cause just seemed... unrealistic?

Personally, I like apocalyptic movies to be (loosely) inspired by science... so here are 5 reality-based ways to start a zombie apocalypse, such as:

• Poison, Drugs and Mysticism
• Fungal Infection
• Viral Infection
• Toxoplasma Infection
• Science, Robots... and Necrobots!

Poison, Drugs and Mysticism

Did you know that the term "zombie" comes from the old African word "zumbi" or corpse?

Slaves on Haitian plantations believed that you could become a zombie if you took your own life, which would condemn you to work the fields for eternity. When French rule of Haiti ended, the zombie was reimagined as the product of dark rituals. Now, an unfortunate victim would be raised by a priest as a source of labor... and as a display of spiritual power.

Curiously, this bit of folklore might not be completely fictional. Prospective zombies were supposedly poisoned with a mixture that included pufferfish - and thus tetrodotoxin, a paralytic that can make a living victim seem dead.

The story goes that the paralyzed victim would be buried alive by their grieving relatives, only to be dug back up and revived by its new master. The new zombie would be fed with a low-sodium and datura-laced diet... which medically speaking, would leave them confused, hallucinating and pliable.

There's actually been some research into three people who supposedly returned from zombiehood. DNA testing revealed that two of them were just cases of mistaken identity... but the third was identified as a woman who'd died and been buried several years ago. When local authorities authorized the exhumation of her grave, it was found to be full of rocks instead of a body.

While it is a disturbing story (that may even have roots in reality) there's no real risk of a Haitian zombie apocalypse. Not only do these living-dead require creation and handling by a priest, they are not described as flesh-hungry monsters. It might be more accurate to say the Haitian zombie was to be pitied rather than feared.

There is one possible way that you could get an outbreak though. Tetrodotoxin can be found in pufferfish, but they get it from symbiotic bacteria living in their flesh. If those same bacteria were to make the jump between species and start infecting humans, you might get a zombie outbreak (albeit a very calm one!)

Fungal Infection

Anyone who's played or watched "The Last of Us" is probably familiar with the idea of a fungal zombie. This isn't just some literary invention - both Cordyceps and the related Ophiocordyceps really do take over the minds and bodies of their hosts!

These fungi usually infect insects, with different species targeting everything from ants to moths. The infection changes the behavior of the unlucky host even as it consumes them - for example, ants infected by Ophiocordyceps unilateralis abandon their forest-floor homes and climb up plant stems. Once the ant is firmly fixed in place, the fungus bursts out of the ant and sprinkles spores far and wide!

We're still finding new species of fungi that can control animals. In 2021, a nature documentary being filmed in Ireland found fungus (subsequently named Gibellula attenboroughii) infested cave spider corpses latched onto the roofs of cave mouths and cellars. The spiders in question spend most of their time hiding, which suggests that they were forced out into the open by the infection - after all, you'd get better airflow for spore dispersal in a cave mouth!

So do humans have anything to worry about? Probably not, as:

• Our brains and nervous systems are much more complicated than those of an insect, which would make it much harder to control our behavior in any meaningful way
• Our immune system is different to that of an insect and can quickly adapt to threats
• We are warm-blooded, which makes us too hot for many fungi to live in!

That being said, the short life cycle of these fungi means that they could potentially evolve faster than a human. Perhaps it could become a heat-tolerant strain, producing oxytocin and other hormones to make the victim more social?

Regardless, if you happen to see someone climbing up a wall and just staying there... keep your distance!

Viral Infection

Zombies are often depicted as a slow but implacable threat - but sometimes writers go a different route. The infected from the "28 Days" franchise are fast and hyper-aggressive, making them an incredibly dangerous threat that's almost impossible to contain.

The Rage virus in 28 Days was supposedly a mutated strain of Ebola... but rabies might actually be closer to a real life zombie virus - for example:

• The virus can be transmitted by being bitten, scratched, or coming into contact with infected saliva
• The infected may begin to hallucinate, while the area around the infection site goes numb
• Approximately two-thirds of those infected develop furious rabies, becoming anxious, aggressive and energetic (which can result in bites...)
• There's no cure once symptoms appear

Really, rabies is probably the closest you'll get to a real zombie outbreak. It makes the infected aggressive and it's easily communicable, but the victims are still just humans - and sick ones at that. Any outbreak would be short lived, as victims typically perish within a few days of symptoms emerging.

Toxoplasma Infection

Have you heard about toxoplasmosis? It's caused by single cell parasites called Toxoplasma gondii and the CDC estimates that over 40 million people in the USA alone are already infected by it.

This little organism can infect pretty much anything warm-blooded, but it prefers to reproduce inside the intestine of a cat. How does it get there? Usually by being inside an unfortunate rodent!

Here's the weird bit. Most small rodents have an innate aversion to the scent of cat urine - it's a survival instinct really, since it helps keep them out of feline hunting grounds. Rats infected with Toxoplasma gondii lose that fear.

Without any drive to get away from the scent, the rats frequently end up as a feline dinner - which gets the parasite into the cat's intestine to reproduce.

So what could it do to us? Well, we know it can affect human behavior - a 2017 study found that infected humans showed "a greatly diminished response to monetary rewards as compared to their non-infected counterparts." If it can make the average human lose interest in money, could it motivate us to infect other creatures too?

Science, Robots... and Necrobots!

We started with mysticism, so it's only fair to give science a turn as well.

In the late 18th century, Luigi Galvani found that electrifying the legs of a dead frog could cause them to twitch - and his nephew Giovanni Aldini expanded the concept to human corpses. This "Galvanism" seemed to be bringing the dead back to life (albeit briefly) and inspired Mary Shelley's Frankenstein.

Fast forwards a few hundred years and scientists have produced the first "necrobots" (that's not a joke - check the link in the sources.) Some rather morbid researchers found that they could use spider corpses to make an actuator (basically a gripper.) Because spiders move using a system of hydraulics rather than paired muscles, injecting air into the corpse of a spider can cause it to extend its legs... and curl them again when the pressure ceases. They've proposed using them in place of plastic grippers, though I don't really see that catching on!

Other recent innovations include robots that absorb components from other robots or even the surrounding environment, adding them to their structure.

There's also a robot design that harvests organic material to use as fuel. The Energetically Autonomous Tactical Robot (EATR, because of course it had to have a "clever" acronym) supposedly only harvests plant material as fuel... and you never hear of computers or A.I. doing anything unexpected, do you?

So to sum up, we have robots made using organic parts, robots that can add useful components to themselves and robots that can harvest organic material for fuel. Put them all together and... cyberzombies, anyone?

Thanks for reading - you might also be interested in...

• Disturb These 5 Real-Life Vampire Graves at Your Peril... on Vocal
• Zombies of Haiti: Wretched and Real or a Folklore Fraud? on Blogspot

Sources and Further Info:

• Scientists Once Scanned The Brains Of 3 Suspected Zombies In Haiti
• Cordyceps and Orphiocordyceps: the zombie fungi made famous by The Last of Us
• A fungus named after Sir David Attenborough zombifies cave spiders
• Cleveland Clinic: Rabies
• CDC: Toxoplasmosis
• The effects of toxoplasma infection on rodent behavior are dependent on dose of the stimulus
• Humans with latent toxoplasmosis display altered reward modulation of cognitive control
• How Twitching Frog Legs Helped Inspire ‘Frankenstein’
• Necrobotics: Biotic Materials as Ready-to-Use Actuators
• Robots that Grow by Consuming Other Robots
• 'Flesh-eating robot' is actually a vegetarian, say inventors