Reader Janine C. recently asked, “How long can a zombie survive?”  Answering this question is at the core of the Zombie Research Society’s mission, and far too complex for a single blog update.  So we’ll try to divide the relevant issues into several posts.

To start, it’s important to understand that by human physiological standards, zombies are dead.  They have no heartbeat, their blood is cold, and their tissue is in a state of decay.  So it stands to reason that by looking at the specifics of human decomposition, we can come closer to the truth about the Zombie lifespan (or deathspan, as it were).

The human corpse goes through several distinct stages of decay: fresh, bloat, putrefaction, etc.  In her 2004 New York Times Bestseller, STIFF, Mary Roach clearly breaks down this progression, offering important information about each stage, particularly the first:

“The hallmark of fresh-stage decay is a process called autolysis, or self-digestion.”

Roach goes on to explain that all of the body’s internal organs liquefy in the fresh stage, including the brain.

In fact, because the brain is so soft, and so close to hungry bacteria in the mouth, it is one of the first organs to go.  By the second stage of decomposition, bloat, the brain has already been turned into a worthless puddle of goo, unable to keep from leaking out of the nasal cavity, much less control the actions of a bloodthirsty zombie.

Therefore, it seems likely that a zombie’s lifespan lasts as long as the fresh stage of decomposition, and not one moment longer.  We have only to discover the length of fresh stage decay in zombies, to know when their deathspan is over.



  1. According to this website, “A zombie is a biologically definable, animated being occupying a human corpse.” The infecting agent need not be a virus or bacteria. Fungi and even parasitic worms are capable of reanimating insects like ants and crickets. The infecting agent could even be a concoction of venoms produced in the salivary glands, which would help explain the infection by bite.

  2. When you dry cure a country ham, the process creates an environment where bacteria cannot grow. After curing and smoking, these hams can be aged for years without refrigeration and are still good to eat.

    Zombification also preserves the tissues, just like a country ham, only the tissues are animated, and you wouldn’t want to eat one.

    Zombies can live past the normal decomposition stages of a dead animal body.

    • Good point, only the ham can’t be cured in the elements, nor can you store a cured ham in the elements. Also if the zombies muscles and organs had the texture of a cured ham, said zombie would be kinda “brittle”( That’s not really the right word, but it sorta conveys )

  3. I would still have to go with some sort of disease/infection type zombie senerio. If they were actually dead(no heart beat at all) then the organs wouldn’t work. Once a zombie did in fact eat something that would sort of be it. No more hungry zombie. It’d just take a nap like we do on Thanksgiving. Disregarding all the other organs of course….

    • First, I am new to this blog, and have given zombies a lot of thought. Please bear with me and my wordiness. Take a break, get some coffee. Come back to it. Thanks.

      One thing that seems widely accepted is that zombies last longer than the average dead body. If they didn’t, the plague would be self limiting and survival rates would be much higher than seen in the documentaries in your local theaters. Yes, the fact that zombie movies are passed as “fiction” is only a ruse to mollify and desensitize the public.

      Anyway, the zombification agent (virus, bacteria, etc) must compete with what causes the decay in the first place. Bacteria. Our bodies are normally mostly sterile, except defined areas (gut, sinuses). It is my opinion that the sterility of the tissues is maintained by the virus destroying the normal flora that lives in and on the body, as well as in the environment. An auto-mummification. Of course, this is not a perfect process, and some slow decay occurs. The organs, therefore are dead. The nerves and muscles must still be functional, that is, cells and structure intact. A freshly dead frog’s legs will jump when zapped with live current.

      The brain question… I believe that the brain is also physically intact, slowly decaying, like the rest of the body, but has a while until non functional. Therefore it is still vulnerable to blunt trauma, gun shots, etc. The highest concentration of the virus is in the brain and head. The brain is therefore, the last to decay. This is also why bites are so lethal and have a 100% transmission rate when the skin is broken, or zombie bodily fluids make contact with mucus membranes or even the smallest open wounds.

      Assuming the virus was cooked up in a government lab, it may be by design that the zombie is mindless, has no safety awareness, no survival instinct, and cannot feel pain. It is both a great military biological warfare weapon and/or a good way to convince people to vote Republican. Rush Limbaugh always was a little suspicious, wasn’t he?

      Thank you all for reading this far.

  4. Tim’s right. As Dr Michael Harris argues (http://goo.gl/YLQPo) zombies require brain function from living brain tissue, which in turn requires an oxygenated blood supply therefore requiring breathing; however the brainstem is the only required part therefore less breathing and heart-beating is required by a zombie. So a zombie’s heart still has to beat, just very slowly, and it still has to breathe just not very much; that’s why when you shoot it in the forebrain it has no effect, and when you shoot it a few times in the lungs, it achieves very little, because zombies only need a small surface area in their lungs to survive.

    Zombies move slowly because of this decreased blood and oxygen supply. Therefore one can hypothesize that zombies in temperate climates would move faster than ones in cold areas.

    Zombies’ characteristic gait can be explained by damage to the basal forebrain (the part affected in Parkinson’s disease) which is highly sensitive to oxygen concentrations, and supports the reduced blood-flow theory. A zombifying virus might have evolved to control bloodflow around the brain, cutting off less important areas of the cerebrum and just keeping the minimal complement required for survival and transmission.

    Maybe we should all copy the wise Dr Michael Harris and move to Alaska.

  5. This debate is one seemingly without end, and the truth is that no one will ever really know until the actual proliferation of the zombie apocolypse, I think the best rule would be to assume that a Zombie is incabable of living beyond a normal human lifespan, for example if a zombie was “zombified” at age 30 it will not be able to live more than that persons lifespan, had they not becomes a zombie. Making the assumption that a zombie would age at a similar rate to a normal human. Programmed cell death or “apoptosis” would ensure that zombies would have an unavoidable expiry date however i would imagine that short of a bullet to the head this is the only thing that would cause a zombie to expire. Were it not for viruses, diseases, accidents etc. all living things would live till their cells could not divide anymore and it is probable that zombies would not be affected by the afflictions that usually make a person of that age weak and frail. Also taking into consideration the assumption that zombies cannot feel pain, It looks to me like zombies could in fact have a lifespan far in excess of your average human and remain an active threat for well over 100 years. This theory does depend on the fact that a zombies cells do indeed continue to divide like that of a living creature, but I think it is a possibility worth considering.

  6. I think zombies would be normal humans infected by some biological weapon or disease that would disable the part of the brain where emotions are stored and memories; The neurosystem could be damaged aswell by this disease. What do we get with a human who feels no emotions, memories or pain but only with the need for basic functions like feeding. I think this is the most realistic way zombies can ever exist but then again i’m no expert 🙂

  7. ( I am going on one of the many theories that the zombies will be undead >with no pulse and have no heartbeat and dont breath or any other bodily system working other than a possibility of digestive 🙂 )
    Alright, now some people believe that zombies dont breath or if they do breath but it is just an action. As we all know if an organism does not take in oxygen -bad things happen. This comment is related to a zombie’s movement. Living humans breath to allow our lungs to deliver oxygen and other stuff to our cells. Our muscles require constant repair, the repairs require oxygen and nutrients. If zombies dont breath then once the muscle tissue is damaged then it is out of function. So by going on this then it wouldn’t be a factor of how long it takes the undead to decompose but a matter of how long it would take for their muscle tissues to be damaged enough to disable movement, if you think about it this makes sense if the zombies are infected with something that will take control after death.

    Awesome Blog ZRS!
    **Best of Luck**

  8. This is actually one of my favourite topics for Zombie related debate. Ive always found the idea of an actual dead creature (human or otherwise) a little hard to grasp. My oppinion being once it’s dead it’s dead. However I do beleiev very much in the parasitic/Viral type of infection that hotwire’s a hosts body, and reprograms them to perform one task mindlessly and repetetivly. Essentially acting to keep a host alive as long as the hosts body would allow.

    I have before touched on the idea that a virus might act in its own way as a type of immune system, fighting off the natually occuring bacteria that proceed to attack the body once it dies. It could act almost as a type of embalming that would in theory negate any sort of fresh decay stage, or prolonging it exponentially. (Until the virus fails to be able to properly protect it’s host.) But given that that no real evidence exists either way I can only theorize by what I know about death and decomposition as a whole.

  9. if the spores do take over ure nervous system if you kill ure self before the virus kills you, you wont turn into a zombie but would that even work?????

  10. Dimitri Matthews

    Also note, that it would take at least 3 to 5 years to decompose. As stated by Max Brooks. I base everyone of my statements off of his book, and works.

  11. I’d just like to chip in with, if Zombifaction was caused by any known microbiological organism then decomposition of the host tissue would be a major hazard, although certain evolved charictaristics could combat it. I’d like to say that a viral outbreak would have little to no defence against decay from my knowledge, whereas there are strains of bacteria and fungi which can produce chemicals which kill off other microorganisms, such as penicillin. Also if theombifaction was caused by a fungal infection then given enough time the fungus could replace the initial brain tissue with it’s own simple neural system, allowing a zombie to continue functioning until the breakdown of either muscle, ligament or tendon tissues.

    • So, you’re saying that in the almost impossible chance that the zombie infection WAS a fungi, it would replace the zombie brain with spores, thereby effectively reducing the zombie intelligence rate to that of a mushroom? Even if that happens, fungi die when the host dies, so once the zombrain liquefies, the resources providing the fungi with the necessary essentials to remain alive will deminish, killig the little ‘shroom.

      • actually fungal infection is just as likely, if not even more so than viral or bacterial infections, due to the fact that several species of particularly south american fungi infect hosts through spores, hi-jack their nervous system and take their host for a ride before disposing of it when the fungi finds an optimum place to release it’s spores. as for the zombie intelligence, well it uses the same mechanisms as the host’s regular nervous system, except it pushes the host towards a single goal, in most current cases that is the top of a tree or a high rock to get the highest spore distribution. also, if the fungi were following in the footsteps of current examples then it would only want to get close to a target, either a high place or a heat source or whatever, and release it’s deadly airbourne spores. so who knows, you might feel safe in your inpenatrable fortress but if it’s open to unfiltered air then you’d still be at risk of fungal infection. so anti-fungals, face masks, goggles and regular full-body skin checks would be required to keep the infection at bay.

        oh and on a general note, if there is a possibility of non-body contact transmission then it might be a prudent idea to get some UV gear and irradiate all your food and water before consumption.

  12. Surely for the brain to function at a capacity enabling actions to a level of those carried by zombies (biting, moving, grabbing etc.) there must be a great deal of activity still taking place within the brain. Hence, this activity would suggest the tissue is still functioning and alive, meaning decay should surely take much longer, and hence the fresh-stage decay/liquification of the organ would not take place so hastily.
    The activity of the brain would also spawn the issues of how the brain is still active. For cells to remain active, energy must be created through the process of respiration in the mitochondria of the cells. This requiring oxygen intake from the surrounding environment, which is supplied to the lungs and diffused into the blood, and carried to the cells. So, without both the function of the lungs and the moving blood supply, this oxygen would not be transported to the cells of the brain, hence no respiration taking place to create energy.
    Is it possible that the virus, once happily infecting the brain cells, creates energy in an opposing way, such as through obtaining oxygen in an opposing way to that of the normally functioning human body, or possibly even consumes the body’s own tissue to create energy. Does this make sense? (:

    • Great comment, Jordan. And yes, that makes a lot of sense.

      In fact, when a person starves to death the body actually eats itself – creating needed energy from digesting its own organs, etc.

      • but the body still needs oxygen…cellular respiration, the process that creates atp, the energy necesary for muscles to contract, needs oxygen..doesn’t work without it, so for a zombie to be able to move it would have to breathe, and have bloodflow, otherwise muscles would work for about 1 minute, at which point they wouldn’t be able to loosen, it would experience rigor mortis

  13. I’ve always theorized that Zombies would only “live” a few days unless they are able to get living flesh on a near daily basis. That’s what holds off decomposition. Let’s assume that Zombies are rife with flesh-eating bacteria (pretty likely), as long as they can eat fresh human meat, the flesh-eating bacteria is satisfied.
    I think it makes sense if you think of a Zombie as a sentient virus, trying to keep itself alive and also trying to reproduce as quickly as possible. These two motivations are at odds with each other, though. As more and more zombies are created, there will be less and less living flesh to snack on, causing the Zombie bacteria to consume any quasi-living tissue in it’s host body.

  14. If I found myself in a mall surounded by the undead would the sprinkling of chia pet seed on the heads of the hordes be unethical. Or would it hurry there demise. If your wrong and they dont die right away the green ronald mcdonald hair might be some comic releif in a otherwise tense sitution. If im going to be eaten by zombies I want them to have chia fros without a doubt.

    • Holly crap that is the funniest idea I have ever heard. I hope that works cause the would be the funniest thing ever

    • Love the chia seed idea. I will never see a Chia head the same way again. I can see a lumbering crowd with blank stares and outstretched arms clawing at the glass with matching green poofy pompadours. The best part is that they would have no idea how silly they look. Brilliant.

  15. I have to say all of these ideas are great the one issue no one really touched upon yet would be the huge issue of location when you legitimize the decomp issue you have to take weather into account. I mean Zombiea in the hot dry weather (Las Vegas, Arizona, etc.) will decompose at a much slower rate than say your Illinois or Seattle Washington zombies. Hands down its all a matter of temperature and the elements—put a t-shirt out side in Vegas a year later you have a dirty slightly rugged looking t-shirt, put it out in Seattle or Illinois and you’ll have frayed rags.

    So in conclusion when you’re taking all other aspects into account don’t forget the weather

    • while true i dont think zombie jerky is gonna pose much of a threat either and plus out there you can see a zombie from a diustance in new york its all mountians and trees and crap

  16. Your all wrong. It is not a biological virus. It is a hybrid biological/nanobot. A tiny robot desighned to rebuild tissue at the cellular level. These nanobots cannot restore uppper brain function or keep up with the rate of decay once in a dead host.they DO keep up well enough to make a zombie last quite long however. The victim become a carnivourous animal. Simple instinct kill and feed.Some body functions are impoved with adrenal glands much like a alligator snapping at a deer feeding by a steam.
    Freezing will immobilize and destroy the tissue but the nano?virus can still be transmitted though the blood once unfrozen.Just the warm hand on the dead body will dethaw enough to be deadly, if they enter a open wound. Frozen zombsicles as we called them at the facility can unthaw and be deadly for a short time. Exposure to High magnetic feilds can destroy the virus permenently.

    Sorry for the spelling inm not thinking to clear

    I hope this helps I was exposed a few minutes ago so I have nothing left to lose by telling the world.

    screw Octoglobal

  17. Perhaps the virus has the ability to block or disable certain parts of the brain which could be a disadvantage to it. Things such as feelings of empathy, fear or pain could all potentially slow or stop the virus’ spread. I reallise that the brain needs to be functioning at a reasonably high level, but there are certain parts that would almost need to be turned off. You can’t just take an average person and tell them to be a killing machine and have them comply.

  18. Well said, Craig. Two thoughts:

    1)We know that the zombie virus is passed through transfer of body fluids – bite, blood into a cut, etc – so the virus is in the blood. It’s not ONLY in the brain. It’s a whole-body virus. Subtle, but important point.

    2) A brain can’t be alive just on primitive levels if you want to be able to grab something. Meaning: pretty much all of the brain has to be working on a relatively high level for Zombies to be doing more than just blankly walking into walls and tripping over any tiny rock in the road. In order for them to be a real threat to us, they have to be able to bite, look around, reach, grab, maneuver. These are extremely complex actions. See my post: Brain Function & The Zombie Lifespan for more on that.

    BUT! None of that means you’re not correct. The Zombie brain may be able to slow (or avoid) decay. More on that in a future post.

  19. Also, if zombification is indeed caused by a viral infection of the brain which keeps the brain somewhat alive and somewhat functional at the most primitive levels. Then the brain matter would not be completely dead and would probably escape the organ-liquification part of decomposition.

  20. Good points, Tim. And I do believe that the Zombie lifespan is much longer than a human’s fresh stage of decay – for many reasons that I’ll cover in a coming post.

    In terms of the brain stem theory: In the human brain, motor function is controlled by many different parts working together, from front to back, and left to right. So if – in your reptilian example – a Zombie was able to walk with only a functioning brain stem, it would never be able to grasp anything (like a person), or bite down, or do anything else remotely resembling a threat to the living.

    I’ve been reading some very interesting research about brain function, and it seems there’s no easy answer. Ultimately, large portions of the brain have to be working for a human to be able to make almost any productive movement (let alone aggressive movement). I’m going to post on this as soon as possible, but more research is required.

    Very interesting topic, though. And really the key to how Zombies work.

  21. It’s important to remember that the only portion of the brain that needs to remain intact is the brain stem. If you look up work on the Reptilian Brain, you will see that this small portion of the brain is what controls basic motor functions as well as survival, physical maintenance and dominance. If something was able to keep this small part of the brain alive, I believe that death of zombies due to decomposition would take far longer.

  22. I have to admit my zombie knowledge is realy just based on movies and my own darkest fears and not even close to what I’m reading about here…Solanum? Toxoplasmosa? I will definitely have to google some words when I get home! Thanks Andrew, your blog is just what I need to fuel my fear of a zombie take over! I’m hooked.

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