As requested by JBH, I edited this question to fit the Anatomically Correct Series.

The classic zombie is no mystery to anyone: undead, eats people and multiplies by biting humans. Could they ever evolve in nature?

A few rules I would like you to follow:

  • They have to be their own species rather than a human turned by a bite;
  • You have to explain why their bodies are in decomposition (or why they look like it);
  • What is their "set of abilites"? Can they run? Are they guided by smell? How strong are they compared to humans? Do they have some degree of intelligence? You are not obligated to answer these questions specifically, but give me some answers in this line of thinking.
  • And last but not least, you have to answer my original question: What is their diet like?
  • 3
    $\begingroup$ I'm going to invite people not to downvote until Magus has decided whether or not to take my advice. I think this would make a fabulous anatomically correct question, but it needs adjustment to meet the rules for that series. Magus, would you be willing to rewrite your question for that series? Follow my link and read the rules (there's not a lot of them). I think you'd get great answers. Please leave a comment and let us know what you want to do. $\endgroup$
    – JBH
    Jul 25, 2018 at 21:51
  • 1
    $\begingroup$ I will check it out @JBH. $\endgroup$
    – Magus
    Jul 25, 2018 at 22:50
  • $\begingroup$ I would be glad to @JBH. Can I do this tomorrow? I will read some of the things written in there to get the format and edit this question so its more robust. Is there a deadline for me to reformulate it? $\endgroup$
    – Magus
    Jul 26, 2018 at 0:32
  • $\begingroup$ @JBH can I answer my own question? I mean... I choose the best answer so I can se how unfair that could be. But I would like to try and give it a shot, if it's okay. $\endgroup$
    – Magus
    Jul 26, 2018 at 18:58
  • $\begingroup$ 😉 It is permissible to answer your own question. If you want to select it as the correct answer, you have to wait a day or two (the system will force you to wait). Should you make that judgment, be sure you've been fair to other answerers. In other words, if you're using data they provided as part of the answer, at the very least be sure to give credit where credit is due. $\endgroup$
    – JBH
    Jul 26, 2018 at 22:15

4 Answers 4


Could they ever evolve in nature?

First, we need to define what is a Zombie and for this, there are some possible theories:

  1. Human-being infected with some kind of virus, fungus or bacteria that kills the host and raise a new being, the Zombie. (Most of my answers will be based on this variant theory)
  2. Variation of the Human race that can infect their similar species and transform us into one of them.

Then, I will answer it by the end of my text after some very important context information explained on the following questions.

Are their bodies in decomposition?

No, this is a common mistake associated with the decomposition odor they emanate. The real answer is that the parasite (virus, fungus or bacteria) is actively controlling the body by providing the electrical impulses that activate the muscles created by a chemical reaction that smells like decomposing bodies.

This is important because the Zombies does not always respond to a single centralized Brain, like for example, a limb cut off will still move for a while before the parasite loses the energy material for the reaction that causes the electrical impulse and the limb will enter in hibernation.

The problem with that is if a limb is stitched to another Zombie, it will be fully operational once the parasite can link both parts.

But if so, why destroying the Brain is the fastest way to "kill" a Zombie?

The Brain is the perfect habitat for the parasite, it has all the nerve system at hand and the skull provide the best protection they could ask for the initial phase of infection.

Disabling it will eliminate the Control Center of the parasite and the body will start to decay, killing slowly the parasite.

What is their "set of abilities"?

How strong are they compared to humans?

About the strength and fatigue the fact the zombies feel no pain, an excess of lactic acid will not bother them nor make them stop using their muscles.

Basically, a regular person will stop overusing their muscles as a reaction either to the muscular pain or the censorial pain related to the pressure applied to their fingers when pressing an object as an example. None of these will stop the zombie.

They will use the original body strength without restriction, what would make them "stronger" than before, also the more they use it, stronger they become and more hunger they will have.

Finally, this hunger will press the adrenal glands to produce adrenaline or epinephrine that will increase the blood flow to muscles increasing the muscular capacity to incredible levels not possible to the Human host before getting infected.

Can they run?

The other aspect is that there are some "exercises" that are aerobic (uses oxygen) and others anaerobic (uses no oxygen).

Zombies will not be able to run a marathon, but they can flex their muscles until its rupture.

Since there are two different types of Muscular fiber in a Human body, the red and the white ones.

The White is used for long-lasting movements like marathons, while the Red is for a fast reaction like 100 meters sprint. A Zombie will exceed in Red fibers and they will be able to run very fast but only for a small amount of time (few seconds) and then they will need to feed.

This characteristic is based on the predator and prey nature model for carnivores, where an animal like a Jaguar can outrun their prey but not for very long.

Do they have some degree of intelligence?

The Zombies will not have Intelligence on their own, but the parasite will be connected to a hive mind, like Bees or Ants and they rely on the smell to send and receive messages and to identify other infected beings.

While having a human covered with blood and gore from a zombie will mask the human smell and make them identify the human as one of them, the decay of the parts will kill the parasite and the characteristic odor will diminish making it possible to differentiate the human smell after some time.

An unconfirmed theory seems to point that Zombies having a hive mind, responds to a Queen-type entity with a higher degree of infection capable of some basic thinking on top of the basic predator instinct.

What other characteristics are important to mention?

When a Zombie needs the extra energy, they will produce adrenaline as mentioned before, this will cause pupil dilation and with that, they will have an increased light sensitivity and better nocturnal vision.

This makes them very active during the night time or really dark ambient like caves or sewers and very slow reactions during the daytime.

What is their diet like?

Zombies eat bloody meat and Brains, but why?

  • They do not convert aliments into energy like regular Humans;
  • Due to their unstable state, they need to keep feeding without a break or they will either perish or enter in hibernation

Since they need to keep eating, they will always seek for the meal that acquires the best resources they need the most.

To regain the used chemical elements, their hunger for bloody meat and brains is the fast way to absorb it from another being that is chemically similar to them.

Roughly they see us a powerful electrolyte and blood meal.

What happens if they do not absorb the chemical elements that they need?

Missing calcium: The low blood calcium level, aka hypocalcemia, causes muscle irritability. This is the cause of muscle cramps and twitching of your muscles.

Based on it, the characteristic twitching muscles and erratic movement of the zombie can be defined by their super low diet of calcium.

If they fail to acquire the necessary amount of meat, blood, and brains, they will enter a critical state that can put them in hibernation.

Zombie evolution

Please consider this part of my answer as possible outcomes, none of this has been proved so far.

To answer the main question, now that we have the basics, it is possible to understand how they can evolve:

The parasite will duplicate in a fast rate depending on the ingestion of more organic material, this will cause it to either jump to another host (infection) or add more organic material to the original Zombie.

When they infect another host, the same parasite will occupy more than one host, what is, in fact, a single organism spread in multiple "Zombies". This allows the hive mind to operate.

To add organic material, the parasite needs to have a established control of the host, this means months or years of infection and the degree of infection will raise.

That effect can create a growth on some parts of the host, creating a new category of Zombie.

So far the common type is the "Worker" like in an Ant society. Then some more specialized variations will appear, the "Carriers", the "Soldier" and "Matrons" with some variants.

  • Workers will just search for more organic material and hunt for preys (Humans are the preferred meal)

  • Carriers are the heavy lifters, they are super strong and can carry very heavy weights, they are powerful, can break strong materials but they are very slow, because of that is common to see the Soldier type protecting their carry activity from other parasite hives.

  • Soldiers are fast and strong, some limbs got a shell type cover that they use as weapons, they usually protect the Carriers when they are moving big loads of organic materials for the nurseries.

  • A variant version of the Soldiers is called Elite soldiers, they have the duty of protecting the Matrons and the big difference is the body armor made of the same shell cover than the limbs. They are a clear evolution of the infection phase. They also rely on other forms of communication for faster response (some kind of sound frequency).

  • Matrons are the ones that produce the organic material that transform the soldiers into Elite Soldiers and Workers in Matrons, they are a big larva-like creature that ingests big quantities of organic material and transforms to smaller and super-concentrate orbs of energy (a human in contact with this product can be infected just by touching it) they are the workers of the nurseries.

  • Another possibility is the Queen-type Zombie, that orchestrate the work of all the others and can explain the origin of the Host Zero.


So you have this species of apes forced a long time ago by predators to live underground where there is almost nothing to eat except mushrooms.

These mushroom were not enough to have all the nutrients they needed to function properly and at some point they realized those who were infected with a flesh-eating fungus were more apt than the other ; the flesh-eating fungus supplied them with the nutrient they needed to thrive despite slowly eating them alive.

They started to infect themselves on purpose to satisfy their needs of these specific nutrient. Soon they also discovered they could increase their nutrient intake by eating each other this was not detrimental to their survival since they had a high reproductive rate but kept their population in check

Not so long ago, a new lineage of zombies that respect each other appeared. Accustomed to eat flesh infected by the fungus, they now have to hunt other species to grow the fungus and satisfy their needs.

Since they have a high reproductive rate they need a lot of flesh, and humans are part of the meal.

So I guess they are ape like in their capacities with limited problem solving, stronger and faster than human.

They have a high reproductive rate and an instinctive symbiotic connection with their flesh-eating fungus. When they have consumed enough fungus, they are stronger and more intelligent.

Since they instinctively infect themselves with their fungus, generally the older they get the more decomposed they are, but it also means the fungus is well ingrained in their body and provides them with enough nutrients to function naturally.

TL;DR Apes breeding like rabbits infected with a flesh eating fungus providing an essential nutrient.

  • Is calcium really that crucial to muscle movement?
    Answer: yes, absolutely. You can think of the way muscles work as two workers walking towards each other along a defined path while pulling the walls of the muscle cell together to cause the muscle contraction. The workers in this analogy would be the myosin in the muscle, it wants to bind itself with the pathway (actin), however when at rest the actin is covered by another molecule called tropomyosin. Essentially the myosin worker can't attach to the pathway to cause contraction until tropomyosin is moved.
    This is where calcium comes into play for muscle movement, calcium binds to another molecule on the actin pathway called troponin which activates it and pulls aside the tropomyosin allowing the myosin to step forward. The calcium later gets released during relaxation again.
    This process in muscles is by no means done individually, there are numerous myosin workers and actin pathways that work simultaneously in each muscle cell and this process of uncovering the pathway and stepping forward is repeated many times for full contraction.

  • How much would they have to eat in order to survive? Take human parameters as a base and consider that they would have to hunt their food
    According to here the average adult needs between 1000-1200 mg of calcium per day. However on further searching it seems 99% of that is actually used for bones and teeth, see here.

  • What alternatives to meat that are bigger on calcium and as abundant as meat are there?
    Dairy and soy would be the best sources typically but as you can see in the first link there are a variety of fruits, vegetables, legumes, grains, nuts and fish that can contain a good amount of calcium as well.

It would actually make more sense for them to go straight for the bones, right?

Unless your zombies develop new enzymes to help digest bone the bio-availability (which is a measure of how much of a nutrient can be digested, not just how much there is in total) of calcium from bone is extremely low, there's a reason bone isn't part of our normal diets. I think it more likely if zombies primarily consume humans that they would get most of their calcium from the contents of our stomach and guts.

  • $\begingroup$ hopefully the analogy with the actin-myosin muscle movement makes sense but if not a quick Google search for that should give you a number of clear diagrams how it works, it should be possible to find videos of the process as well even $\endgroup$
    – BKlassen
    Jul 25, 2018 at 22:43

They have to be their own species rather than a human turned by a bite;

Very well. Homo zombus, commonly called "Zombies," are hominids distinguished by their small snouts and fungal and bacterial growths that cover their skin.

Internally, several organs are smaller than in comparable hominids, as their functions have been taken over by symbiotes.

The fungi, commonly referred to as "Ghoul Dust," are in fact several species of yeast that have formed a symbiotic relationship with H. zombus.

You have to explain why their bodies are in decomposition (or why they look like it);

They do not look much like their bodies are in decomposition, but they definitely smell like it. The fungal growths on their body produce putrescine, methane, and other gases emitted by the Ghoul Dust. The Ghoul Dust also produces several toxins. Some of them act as antibiotics that aid the zombies' immune systems, while others are used as poisons for anything that touches a patch of ghoul dust. This includes decomposer insects, who are attracted to the gasses. Healthy Ghoul Dust is sightly sticky, letting it hold onto insects that land on the patches and digest them.

The flattened snout, on first glance, will appear to a human as a nose that has rotted away. The white of Ghoul Dust and the green of photosynthetic bacteria make zombies appear to be rotting at first glance. This, combined with their corpse-like smell, made the first people to discover them think they were walking corpses.

And last but not least, you have to answer my original question: What is their diet like?

They are pursuit predators and scavengers. The scent from their fungi makes stealth impossible, but as hominids they would possess similar features to what made humans effective pursuit predators. Scavenging is a no-brainer; their own microbiome will kill or assimilate anything harmful in the rotten meat.

What is their "set of abilites"? Can they run? Are they guided by smell? How strong are they compared to humans? Do they have some degree of intelligence? You are not obligated to answer these questions specifically, but give me some answers in this line of thinking.

1: Running: Like humans, they are decent at short range, but can keep going far longer than anything else.

2: Smell versus sight: Zombies rely more on smell then sight, as changing fungal/bacterial growths make sight-based identification less likely to develop.

3: Intelligence: Zombies are less intelligent than humans, but more intelligent than apes. They can create simple tools, are social, have theory of mind, but their communications do not have grammar. Zombies cannot develop clothing, as the restriction of airflow plays havoc with their microbiome, with something like athlete's foot being a major disruption, as opposed to the annoyance it is in humans.


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