Zombies are reanimated corpses by definition . If so, then they decay as a normal corpse does. Without any preservatives ( for corpses ) what should be the maximum and the least amount of time people would need to hide, till the zombies become skeletons ( in a world filled with zombies )

Also the possible repercussions of so many zombies decaying. How would it affect the ecosystem ( without the zombies directly hunting animals ). That is if there are any other repercussions other than those caused by the 'short' removal of humans from the food chain.

Edit :

Correction. how long, till they are at the point where they can no longer move, and let's say 10 days after that, they die for good.

  • $\begingroup$ "If so, then they decay as a normal corpse does." - why? If that's what you like in your world, so be it, but it doesn't have to be true. "till the zombies become skeletons" - at what point of decay zombie is no longer able to move? No longer contagious? $\endgroup$
    – Mołot
    Commented Mar 28, 2017 at 13:03
  • $\begingroup$ Good one ! I will edit it, so it says, till they can no longer move. $\endgroup$ Commented Mar 28, 2017 at 13:05
  • $\begingroup$ This question might help you with some aspects of your story. FUrthermore you mention the effect on the ecosystem. To help you with that we would need to know how many zombies there are. Though I don't really see why the ecosystem should have any real problems. Just a bunch of humans walking around. Not with a heart-beat and it takes (maybe) a few days until they decay, but other than that there shouldn't really be a large scale problem if only humans are affected. $\endgroup$
    – Secespitus
    Commented Mar 28, 2017 at 13:09
  • $\begingroup$ Animals tend to eat corpses... other than that ( excluding the transmission of the virus ) eating a corpse isn't something many animals would do, but some will. Saying that they aren't affected that much, after a period of time let's say that we eat those animals ( that have eaten zombie corpses ). Normal cooking would solve everything ? ( Heard that cooking kills all the microns and so on. Also let's say that the go into a 'hibernation' kind of state, to survive the cooking ( in biology some stuff if I remember build a 'shell' like thing to survive under the worst circumstances ) $\endgroup$ Commented Mar 28, 2017 at 13:17
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    $\begingroup$ Just a hint, as you accepted the answer after a few minutes and with a total of 45 minutes since you asked the question: it's often a good idea to let a question without an accepted answer for a day or two so that others have the chance to have a look at it. People using WorldBuilding live all other the globe in different timezones, many having jobs with different working hours. After only 45 minutes only 33 people have seen your question at all. You would be surprised to find out how creative others might be. Just a hint for the future, as accepting can discourage others from answering $\endgroup$
    – Secespitus
    Commented Mar 28, 2017 at 13:44

2 Answers 2


This is going to be dependent on a few factors.

  1. Is there bacterial activity inside the zombie? Most corpses start decaying internally as gut bacteria spread out, causing bloat and putrefaction of internal organs. You could expect significant decay in 4-5 days in a fairly warm temperature. In hot environments it can happen in just a day or 2. But if the zombie creation process sterilizes the gut, then decay will occur much more slowly.

  2. What is the ambient temp? Dehydration (and eventual mummification) in warmer, dryer areas is the ultimate fate of any zombie not consumed by gut bacteria. I would expect significant dehydration after just a few days in a dry, warm environment.

  3. Mold and fungi from the skin and environment will start to grow on the dry and cracked areas of a zombie within a week or so. Moist areas exposed by cracked skin will be affected first.

  4. Scavenger activity by ants and the like will be slow but eventual. If gut bacteria is dead, would fly larvae survive? They can set up in just a few days. A moving zombie will probably ward off most birds until they learn that the zombie is still good meat. Same with scavenger mammals like coyotes or hogs.

Assuming wholesale death of most humans into edible meat or edible zombies, there would be a lag in the explosive growth of scavenger animals and insects. Fly swarms, ants, and roaches would be the first. Scavenger birds, turkey vultures, and small mammals next. Larger mammals last, as well as animals that prey on the insect and small mammal swarms.

Lots of rotting meat can contaminate running water with gut bacteria that is harmful for humans to ingest, like e-coli. Fly populations can carry around harmful bacteria as well, as can rats. So urban areas with lots of dead bodies would be hazardous without protective gear (check out natural disaster recovery like from landslides or earthquakes to see what hazards there are).

Of course without humans around, there would be a concomitant die-off of human supported animal/plant systems. Lots of dead pets inside houses and dead cows, hogs and chickens in pens without food/water. Loose dogs would form packs and go feral, loose pigs would do the same. Loose cats would be fine, they are feral already :P

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    $\begingroup$ Already better than what I expected in a short amount of time. Actually, I imagine I didnt even expect an answer as good as yours in the first place. $\endgroup$ Commented Mar 28, 2017 at 13:43
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    $\begingroup$ Well, this is all avoiding the issue of zombie biology in the first place. As ATP depletion occurs they would undergo rigor mortis and be unable to move in just a few hours. Then, in 2-3 days, their muscles would have decayed to the point where they couldn't keep muscles contracted. So if you assume they somehow overcome that biologic process, then avoiding internal decay seems trivial. But dehydration would be inevitable unless they drink water and have some mechanism for distributing the fluid to their tissue. $\endgroup$
    – Jason K
    Commented Mar 28, 2017 at 14:12
  • $\begingroup$ Lel... aside from rigor mortis ( can easily be explained on how to get by it ) I wanted your kind of info. $\endgroup$ Commented Mar 28, 2017 at 15:47
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    $\begingroup$ My reasoning for rigor mortis is ( zombies is purely a fictional character, but if we try to rationalise it a bit ) he is still a human, just having overdrafts his life and with his brain cells mostly dead or unable to function properly. Thus returning him to a primitive state. The damage to the brain cells is by a serious luck of oxygen. The reason of why only the basic functions have survived is because the virus purposely saved those parts of the brain so as to use it to his own advantage. The virus then gave some stimulation to the very most important parts of the body ( aside from the $\endgroup$ Commented Mar 28, 2017 at 15:50
  • $\begingroup$ Aside from the brain, the organs functionality is a bit more ( for heart it's about half an hour to a full one )) and the organs, whilst damaged as many other parts of our body ( which explains the slow running speed ) the blood still flows, and it is a half living body. My best explanation for rigor mortis on zombies. $\endgroup$ Commented Mar 28, 2017 at 15:53

If you ask how fast a zombie becomes biologically unable to keep operating the answer is: it becomes biologically unable to operate at the moment the living person dies. A dead corpse cannot biologically work anymore.

Truly undead zombies after all, are impossible to exist with our understanding of biology, chemistry and physics. By undead I mean a dead being that still somehow retains some traits of a living being. A dead being does not have the ability to move, as it muscles don't work, after all. It does not have a nervous system to control muscle movements or have anymore working sensory organs to observe anything. All of these biological systems are broken in a dead being.

Thus undead zombies could only exist if they are fueled by some unknown force that can run or simulate biological systems of a now dead being. In this case it is up to the storyteller how the zombie keeps decomposing and set a point when they become unable to work. However with this logic a walking zombie is as "possible" as a walking skeleton.


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