Are Zombies a Reality? 10 Reasons the Undead Can't Stroll Among Us

First, gather the essentials for daily survival—water, food, medicine, and a ton of weapons. Then, evacuate crowded areas, because where people are, desperate souls will do anything to survive. The third step is to locate a safe haven to protect you from the roaming zombie hordes—massive groups, all hunting for human flesh.

From TV shows like 'The Walking Dead' to films like 'Train to Busan,' which depict the spread of infectious diseases altering the human body, you might find yourself wondering: Are zombies real? Fortunately, based on our current understanding of human biology, zombies are nothing more than a myth.

What Are Zombies?

Zombies are reanimated beings that hunger for human brains and flesh. They are a staple in folklore and pop culture. Writers and scientists have proposed various theories for how a zombie apocalypse could unfold. Sometimes it's due to a virus, other times radiation exposure, and occasionally it's the result of a parasitic fungus.

The zombies in 1968's 'The Night of the Living Dead' were initially referred to as ghouls. However, they certainly displayed many of the classic traits of what we recognize as zombies today. They slowly yet steadily pursued any living humans they could find, making up for their lack of speed with relentless persistence and vast numbers.

Modern portrayals of zombies, like those in 2013's 'World War Z,' may reflect the faster pace and interconnected nature of today's society. These undead creatures are not only capable of running down slower victims but also exhibit flashes of intelligence.

Zombies present a physical contradiction. They are technically dead but move as if they're alive. Some shuffle slowly, while others are quick and relentless. They are cold and lifeless, yet they somehow manage to crack skulls and devour brains. Even in their decaying state, they stagger through city streets, grabbing any unlucky soul they come across.

In the following sections, we’ll dive into 10 reasons why zombies couldn’t possibly exist in the natural world.

10. Humidity is Hell

Ever been to Atlanta in August? The word 'stifling' doesn’t even begin to describe the agony of sweltering temperatures and humidity levels that rival a greenhouse. On the other hand, North Dakota in January isn’t much better, freezing living tissue in minutes and wiping out anything foolish enough to venture outdoors without protection.

In short, Earth’s unforgiving weather would wreak havoc on any human zombies in numerous ways.

High temperatures and humidity accelerate the decay of rotting flesh by creating ideal conditions for insects and bacteria, which break down anything they encounter. In the arid heat of a desert, reanimated bodies would dry out into husks within hours.

The bone-crushing cold of winter would make zombie bones even more brittle and fragile. A single misstep or fall could cause their skeletal structure to collapse entirely, possibly even under the weight of their own bodies.

Let’s not forget the damage caused by ultraviolet sunlight, hurricane-force winds, torrential rain, hail, or massive snowdrifts. These harsh elements may be the reason so many zombies seem to favor the relative safety of basements, dungeons, and abandoned prisons.

9. They're Kinetic Catastrophes

We're all biological machines in a way, our movement powered by the connections between muscles, tendons, bones, and much more. When any part of that system malfunctions, our mobility is severely limited or completely stopped.

This makes it even more baffling that so many modern zombies can still move around, despite their flesh and bones hanging by a thread.

Yet, the behavior of zombies is filled with contradictions. They shuffle — sometimes at an alarming pace — seeming unaware of the impossible physics propelling their decaying, shredded muscles and shattered bones. This is before you even factor in their lack of brains.

The human central nervous system is responsible for all muscle movements, transmitting electrical signals from the brain to muscle cells, which respond by twitching according to the brain’s commands.

Many zombies seem to have suffered catastrophic head injuries, resulting in brain damage, which makes the concept of them moving forward even harder to believe.

8. Impossibly Immune

Viruses, fungi, bacteria, and other microscopic invaders have been tormenting humanity since time began, cutting our lives short and often making life miserable. However, it wasn't until the 1800s that we realized that the smallest of these invaders, like smallpox or HIV, can be the deadliest of our biological foes.

Our immune systems, armed with an arsenal of white blood cells, fight off infections and keep us alive... at least for a while. People with weakened immune systems face a variety of health struggles.

Zombies face the same fate as those without immune systems. Their fleshy bodies provide an ideal environment for bacteria, fungi, and viruses to thrive, and these pathogens would quickly devour the zombies from within.

And considering they’re zombies, this is probably for the best.

7. Metabolic Meltdowns

We eat food to transform chemical energy into the functions that sustain life, from respiration to reproduction. Metabolism is the process that regulates these vital activities. Metabolism refers to all the chemical reactions that occur within our bodies.

In theory, zombies crave brains because, like us, they need some form of sustenance to keep their functions going. But there's one issue — zombies are not actually alive. As part of the undead, they completely lack any metabolic processes.

For humans, the nutrients we consume start breaking down as soon as we begin chewing a slice of pizza or quiche. Our digestive systems take over, converting these nutrients into the calories necessary to keep us alive.

Zombies, however, have no metabolism to speak of.

Even if they somehow managed to gather the energy to munch on some delicious brains, their stomachs (assuming they even have one) would lack the chemical pathways needed to convert food into energy, leaving them immobile, inert, and ultimately lifeless.

6. Dog Eat Dog Eat Zombie

Hyenas, wolves, bears, coyotes, foxes, and even packs of wild dogs — when the apocalypse hits, you'll have to worry about these predators just as much as you do zombies. They're swift, fierce, and when hunger strikes, they become increasingly aggressive, willing to take down healthy humans.

So, how would these animals respond to the sight and smell of the undead, who are little more than walking meat bags?

In a world thrown into chaos by a zombie outbreak, survival becomes an uphill battle not just for humans but for the animals too. Like people, these animals will do whatever it takes to survive — even if it means gnawing on the decaying, twitching remnants of someone’s loved one.

It's not only the top predators that would be a threat. Even smaller creatures like rats, raccoons, and opossums would gladly feast on the undead if the opportunity arose — perhaps a zombie with no arms or legs, lying helpless in a muddy pit, waiting for its inevitable demise.

5. Sensory Underload

Vision, hearing, touch, taste, and smell are all essential for our survival. Without our five senses, we'd be lost, likely to consume poisonous plants, crash into door frames, and stumble over coffee tables until we meet a quick end.

Given that zombies are in a constant state of decay, it's hard to comprehend how they'd manage the necessary tasks to hunt for fresh brains.

As their bodies rot away, the soft tissue in their eyes would likely be the first to degrade, leaving zombies blindly reaching for anything unfortunate enough to cross their path.

Their eardrums would disintegrate and tear apart, along with the rest of their hearing system. Deaf and blind, zombies would then rely on their sense of smell — though their own foul odor would likely overpower any scent they try to track.

This means zombies would have to feel their way through the world. While a group of them might occasionally catch a victim, in most situations, fully functioning humans could easily avoid these mindless creatures.

Biting isn't exactly an efficient method of transmitting a disease. In fact, it’s quite a useless tactic for one zombie or zombie-like entity to bite another.

Measles is a disease so highly contagious that nearly 90% of people exposed to an infected individual will also fall ill [source: CDC]. It's a stealthy virus too, surviving for up to two hours outside the body, lingering in the air, just waiting for an unsuspecting person to inhale and start the cycle again.

Then there are zombies, who rely on biting to spread their infection. However, this method of transmission comes with a number of problems, starting with its massive inefficiency.

The zombie bite method for spreading their contagion is full of flaws, primarily because it's an incredibly ineffective way to transmit disease.

First, a zombie has to somehow catch hold of a person long enough to land a bite. This is quite a challenge for a creature that might be missing limbs, making it difficult to chase after panicked prey. Second, the act of biting uses up vast amounts of time and energy, both of which are in short supply for a decaying zombie.

Third, biting requires close physical contact with the victim. With survivors constantly on edge and scarce, those slow and stiff zombies would have a hard time getting close enough to their warm-blooded counterparts.

Zombies are stuck with wounds and decomposing tissue that can never be healed. No skin care routine will save them from further deterioration.

Before antibiotics became a staple, even the smallest scrapes and cuts could be a deadly threat to humans. A simple cut could invite dirt and bacteria to sneak into the body and cause trouble inside.

With the right hygiene practices, such as cleaning wounds and washing hands, most individuals would recover from these types of injuries, though the healing process might be prolonged and sometimes result in lasting effects.

Unlike humans, whose tissues regenerate and heal, zombies do not possess this ability. Their injuries, whether small or large, are irreversible. Imagine a paper cut that never heals, but instead keeps growing wider and deeper each day. As the flesh continues to break down, more bone becomes visible, and eventually, the remaining flesh falls off.

Even a minor scrape would cause a zombie's skin to blister and peel away, leaving sagging layers that slide off their body. Burned skin would transform into a gooey, foul mess. In a way, this decay is for the best—no one wants to stay a zombie forever.

Zombies likely can't properly digest food. Regardless of what they consume, it will ferment and ultimately lead to a nasty explosion.

Your stomach is a flexible muscle that can hold around 30 ounces (0.89 liters) of both liquid and solid foods. People who habitually consume large portions may stretch their stomachs to accommodate more, while those on strict diets may actually reduce its capacity.

It’s safe to say zombies won’t be joining Weight Watchers anytime soon. These creatures are the ultimate competitive eaters of the monster world, always ready to indulge at any brain buffet they can find.

While this eating style might sound appealing, it comes with some significant issues, and none of them have anything to do with a zombie worrying about their figure. The real problem is where their food ends up after they devour it.

Since zombies don’t possess fully functional bodies, they likely have holes in their digestive system, somewhere between their mouths and their anuses. These gaps make it impossible for them to gain any benefit from their meals.

Naturally, since so many parts of a zombie’s body are nonfunctional, the brains they consume are likely to come to a halt (pun intended) at the point where the esophagus meets the stomach.

As the zombie consumes more and more brains, the remnants that can't be digested will begin to ferment, producing gases that will eventually rupture the zombie's stomach walls.

Once those teeth inevitably fall out — and trust me, they will — this unfortunate creature will find it increasingly difficult to tear into its meals.

The crucial part of that statement is the need for proper care. Drinking sugary sodas and skipping flossing can lead to years of dental agony, including cavities, receding gums, and a host of other painful problems.

Skipping essential oral hygiene can result in a lifetime of dental distress, and that's definitely a fate you don't want to face.

Zombies don't exactly follow a good oral hygiene routine, even if they still have teeth. As their gums decay and their enamel chips away, their teeth become discolored, pitted, and eventually fall right out, making any attempt to bite you utterly ineffective.

However, a zombie's teeth are likely the last part of its body to deteriorate. Even if those teeth break or crack, they can still serve as effective weapons, especially if you make the mistake of getting too close.

But realistically, that’s unlikely to occur. At least for now, there's no virus, radiation leak, or fungal outbreak that's turned the world into a zombie wasteland.

On the upside, you’ll probably never have to fear being chased by hordes of the undead, stumbling, groaning, and reaching for your flesh. Unfortunately, that also means you won't get the chance to test out your carefully crafted zombie survival plan.

In any case, zombies are a scientific impossibility. It would take some truly extraordinary magic for them to ever become a real threat to humanity.