So when I say everything, I mean everything. Humans, animals, plants, fungi, bacteria, all dead. If the bacteria and other detritovores and decomposers can't decompose anything since they themselves are all dead, what happens to all the carcasses and remains of the life?

Do these remains decay through other inorganic means? What do they look like throughout this process? And how long would it take?

(For the purposes of this question, let's just say that Viruses and Prions count as "alive", they are "killed" in this scenario as well)

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    $\begingroup$ This question is almost identical, but the key issue is that it doesn't address the specific thing I was asking in my question. worldbuilding.stackexchange.com/questions/14911/… And another similar question on Quora doesn't answer what I need to know either: quora.com/What-will-happen-if-there-were-no-decomposers $\endgroup$ Commented Apr 19, 2018 at 11:13
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    $\begingroup$ A much more interesting question would be how long it would take that from those huge quanitities of biological molecules, a new form of life would be created. $\endgroup$
    – PlasmaHH
    Commented Apr 19, 2018 at 14:08
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    $\begingroup$ Prions are "killed"? Prions are nothing but destructively shaped proteins. If you're going to go so far as to denature proteins everywhere, you're well on your way to decomposing everything right there. $\endgroup$ Commented Apr 19, 2018 at 21:42
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    $\begingroup$ @AdamMiller Next on Apocalyptic Scenarios: "What would happen if everything were to spontaneously decompose?" Stay tuned to find out! $\endgroup$ Commented Apr 20, 2018 at 8:45
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    $\begingroup$ None of the answers have mentioned oxidation, which is a destructive process that doesn't require living organisms. $\endgroup$ Commented Apr 20, 2018 at 13:24

10 Answers 10


They weather.

seal mummy


Antarctica has dry valleys where, for some reasons, seals sometimes went. It is a bad place for seals, and they died. It is a bad place for microbes and everything else too, so the dead seals did not decompose. These mummies are hundreds of years old.

The mummies weather in the elements. UV radiation breaks down tissue. Wind and windblown grit wear it away. It is much like what happens to wood left outside in a dry environment.

In a world without scavengers, fungi or microbes, these processes would be what gradually took away the remains of the world's life. I do not think warm circumstances would matter as much in the absence of life. Wet would matter but much less than it does when there are fungi - the water would carry away degraded bits as the rain washed the mummies - so they would vanish faster than these seal mummies in the dry valleys.

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    $\begingroup$ +1 for the vivid image. It shall be forever printed in the back of my eyes. shivers $\endgroup$ Commented Apr 20, 2018 at 12:55
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    $\begingroup$ Anywhere with seasonal freezing would also wear away faster as the freezing and melting of water would break down tissue $\endgroup$
    – Kaosubaloo
    Commented Apr 20, 2018 at 22:26
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    $\begingroup$ Warmth does matter, because chemical reactions are faster in higher temperatures. It is the reason erosion of any given rock type is different in the tropics and the temperature latitudes. In cold climates physical erosion is more important (frost shattering, etc), in warm climates chemical erosion is more important. $\endgroup$
    – DrBob
    Commented Apr 21, 2018 at 18:32
  • $\begingroup$ Oooh, spookt! This might give me nightmares! $\endgroup$
    – Leviathan
    Commented Aug 16, 2022 at 17:51

The remains would mummify, petrify, erode, and eventually become just another mineral layer.

Where water is available the organic remains will dissolve and be replaced with inorganic minerals to form fossils, and if no water is available the remains will desiccate and be preserved as mummies.

There wasn't much specification regarding the timeline or location, so the below are just the general process that will occur over a long period of time.

Mummification: In particularly dry areas like deserts or mountain peaks, the remains would mummify, much like this creepy fellow. Even with regular decomposition mummification can still occur naturally, so without scavengers and bacteria getting in the way much of the life in dry areas would desiccate and mummify.

Petrifaction: In areas with water, the remains would petrify. Water would leak into the pores of tissue and bone, and minerals within that water will precipitate out and saturate the remains, resulting in a combination of organic and inorganic remains. This process is called permineralization, and is the reason we have dinosaur fossils. Without bacteria, the soft tissue remains would also go through this process and become fossilized.

Over time, much of the organic remains would slowly be dissolved by water and replaced by minerals, in the uncreatively named process of replacement. Unless the fossilized remains reach a dry area, they will eventually lose all of their organic components and be no different from oddly shaped rocks.

Erosion into Mineral Layers: As explained above, the organic material in the remains will slowly dissolve and be washed away by water(and probably other chemicals). The dissolved bones, shells, beaks, and corals of the trillions of dead will pile to form layers of limestone, rainforests will turn into vast swaths of coal, fossils and mummies would be formed in amounts to put previous extinction events to shame, and the swarms of dead ocean critters won't even get to become oil without bacteria. If given enough time, even the petrified and mummified remains will erode like an other rock, leaving little evidence of life except layers and veins of organic minerals.

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    $\begingroup$ Deserves a green checkmark $\endgroup$ Commented Apr 20, 2018 at 0:26

Unless you totally destroy all proteins everywhere, I'm going to bet that some of the very simple forms of life will find a way to recombine after 'death', and rapidly turn the earth into bacterial soup. Most theories of the beginnings of life involve rogue proteins teaming up to eat other stuff, and I suspect some simpler single celled organisms would spontaneously do this right away, given the incredible abundance of defenseless, energy rich raw material all over the place.

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    $\begingroup$ "Bacterial soup" makes me think of 3-week old clam chowder $\endgroup$ Commented Apr 20, 2018 at 0:28
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    $\begingroup$ @forest: it depends on the definition of "dead", then. All that molecular machinery just sitting there surrounded by piles of DNA and RNA, the only thing missing being fuel or something... Could make a good followup question for this site, if you can be specific about how dead and what's left of the proteins / RNA and the molecules that process RNA. $\endgroup$ Commented Apr 20, 2018 at 7:57
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    $\begingroup$ @PeterCordes Death is usually defined as the irreversible cessation of all vital biological functions. As for what is missing, it's far more than fuel. Very quickly after ATP synthesis stops, membranes will oxidize and lyse, and I would be very surprised if lytic cells could somehow reassemble. For many vertebrates, even "brief" necrosis will cause phosphatidylserine to move to the outer leaflet of the membrane, which condemns the cell to death even if it is revived. For eukaryotes, the mitochondria would also lyse, and the corresponding calcium efflux would be extremely cytotoxic. $\endgroup$
    – forest
    Commented Apr 20, 2018 at 7:58
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    $\begingroup$ @PeterCordes I imagine it could be engineered to occur, if a cell were to produce self-replicating ribozymes then even after lysis, they could survive on ambient nucleotides if kept in the proper environmental conditions (since obviously they would lack any means of homeostasis themselves). The RNA world hypothesis is still the most promising for abiogensis, after all. What really matters is how everything dies. Causing all cell membranes to vanish into thin air would certainly do the trick, as would destroying every nucleotide, but only the former would allow for an RNA world afterwards. $\endgroup$
    – forest
    Commented Apr 20, 2018 at 8:07
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    $\begingroup$ I've heard that a gamma ray burst would sterilize and kill everything. But I don't know how intact protein chains would be or how long it would take to recombine and become "life" again. Also some stuff in volcanic vents or deep underground would probably survive. $\endgroup$
    – Zan Lynx
    Commented Apr 20, 2018 at 18:01

Things would still decompose, but maybe not as fast, dependig on environmental factors. Enzymes and other chemicals found within the (now dead) bodies (or whatever remains) would break those down. Then of course there is heat degradation. And depending on environment (again), interaction between chemicals from both the remains and the environment. And then there is weathering.

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    $\begingroup$ Correct. The speed will vary by temperature. Cold weather will retard the process. But the corpses will still slowly fall apart. $\endgroup$
    – SRM
    Commented Apr 19, 2018 at 12:58
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    $\begingroup$ Very good point. Just because there is no bacteria or fungus to take the body apart doesn't mean that any chemicals already present go away. Stuff like stomach acid would corrode the lining of the stomach, and the body wouldn't be continually repairing itself. Cells would rupture, releasing toxins, eating away at more cells. Eventually there would be a state where everything that can react has reacted, and then mummification and weathering would take over. $\endgroup$
    – AndyD273
    Commented Apr 19, 2018 at 14:57
  • $\begingroup$ Great insightful brief answer. $\endgroup$
    – quintumnia
    Commented Apr 24, 2018 at 18:23

In addition to @Giter's excellent answer, there is another destructor of life remains on land:


Wildfires will not only burn down the dead forests and grasslands but also consume almost all the corpses lying on the earth surface. The ashes will be dispersed by the wind and deposited somewhere, forming a faint geological mark of the end of life as we know it on earth.


Another solution: aliens.

Well, kind of. I am assuming "everything alive in this world" means to a certain height above the earth, probably to the generally accepted limit for our atmosphere. We know for a fact that there are organisms hanging out on most if not all of the sundry items we have put in orbit around our planet. As those deorbit, some of those organisms will probably survive, and start feasting on the lovely food laid out for them on the planet below. It will take some time, but they will likely dominate the earth.

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    $\begingroup$ The ISS has plenty of organisms living inside it that would survive reentry. $\endgroup$ Commented Apr 23, 2018 at 15:25
  • $\begingroup$ 3 to 6, depending on how many crew members are up there at the moment ;) $\endgroup$
    – bendl
    Commented Apr 25, 2018 at 19:37

This is only a partial answer.

Life is essentially an on-going chemical reaction. Killing all life does not stop all chemical reactions, it merely interrupts the reactions needed for life to sustain itself.

Lifeforms contain many different types of chemicals/compounds. Some compounds are fairly volatile and would break down by themselves into simpler chemicals after a short time (hours/days). The stomach acids of animals would partially break down the body until they were too diluted to be effective. Some compounds would dissipate, such as water and oils in a dry environment. If the remains were in water, they would absorb water until an equilibrium was reached.

The tougher tissues (wood, bones, spines, etc.) would last longer than the softer tissues (leaves, skin, blood, etc.)

The more active the environment was, the more weathering would have an effect. After a short time, exposed remains would be subject to erosion and buried remains would be subject to fossilisation. Note that generally speaking, fossilisation is hard to achieve because so many factors have to be present at the same time, although with no life to consume the remains there would be a slight increase in burial events.

Any remains in cold areas would be preserved longer than in hot areas because heat accelerates chemical reactions.

  • $\begingroup$ One exception to "hot is better than cold" - cycles of freezing and thawing might significantly help with the destruction of the remains. $\endgroup$
    – Luaan
    Commented Apr 24, 2018 at 12:15

CJ Dennis is heading in the right direction. Chemical reactions keep happening, and life catalyzes some of them more than others.

There would presumably still be lightning strikes, and eventually most of the dead forests and dead grasslands would be burned to ash. The existing coal mine fires would continue until they got buried or soaked. The main reason the CO2 level in our atmosphere is so small is that plants keep removing CO2. So CO2 levels would rise. But there isn't enough biomass to bring oxygen levels down very much. I think.

Volcanoes and hydrothermal vents release sulfur gases and ammonia. If they weren't metabolized what slower chemical reactions would they get?

It's hypothesized that the atmosphere used to be anoxic, and life created all the free oxygen. Maybe we could eventually get back to that? I don't think the numbers add up on it, I think there's far more oxygen than carbon biomass, but I could be wrong. Still, whatever equilibrium it approached would surely have much more CO2. It might have less N2 and more other nitrogen compounds, or maybe not. Nitrogen compounds are heavily metabolized and N2 is a low-energy form that some bacteria produce when they extract energy from other nitrogen compounds.

Would we get a big greenhouse effect? I'd expect so.

Pretty much everything that's biomass now would eventually get oxidized. The earth would have a very different climate, but it wouldn't be easy to predict just what it would be like. One reason to think it wouldn't just slip back to what we had before life changed it so much, is that the earth is not nearly as hot now.

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    $\begingroup$ Oxygen in the air can react with minerals and metals, not just carbon. As erosion exposes new layers of minerals that can rust, corrode, or otherwise oxidize, the levels in the air would decrease. Life is the only major source of O2, so the equilibrium point with no life is near-zero free oxygen (like before life evolved). $\endgroup$ Commented Apr 24, 2018 at 3:28
  • $\begingroup$ Peter Cordes, you are clearly right. I don't understand this. When oxygen and reduced minerals are present, bacteria oxidize the minerals and get energy. When oxidized minerals are present along with organic material where there is not enough oxygen to oxidize the organics, bacteria reduce the minerals and oxidize the organics. So at first sight, to have a rough equilibrium, we would need more anoxic environments where oxidized minerals are introduced to be reduced, than oxygen-rich environments where reduced minerals are oxidized. Do you have more insight? $\endgroup$
    – J Thomas
    Commented Apr 25, 2018 at 10:47
  • $\begingroup$ My limited chemistry, geology, and biology knowledge doesn't cover that. But with no bacteria alive, I think we can be pretty confident that O2 in the air will eventually react on its own with anything that can oxidize. It's a very reactive element. $\endgroup$ Commented Apr 25, 2018 at 10:53
  • $\begingroup$ wp suggests world total biomass is perhaps 4 x 10^15 kg of carbon. Atmosphere is about 5×10^18 kg, So 1 x 10^18 kg O2. The biomass carbon would bind to almost exactly 10 x 10^15 kg O2 - which is only 1% of the atmospheric oxygen. (I am surprised by this.) $\endgroup$ Commented Apr 25, 2018 at 12:46
  • $\begingroup$ "I am surprised by this." I was surprised too. Maybe the estimate for biomass is off by 2 orders of magnitude? Maybe, wherever there is moist dirt, including the seabottoms, life creates anoxic environments where inorganic materials arrive and their oxygen is scavenged? I think this deserves a question of its own. I tried to write that up here. earthscience.stackexchange.com/questions/13990/… $\endgroup$
    – J Thomas
    Commented Apr 26, 2018 at 14:05

This happened on earth several hundred million years ago: lots of oil fields will form.

edit: unless there is no volcanic activity, in that case it will just lie on the surface. If there is an atmosphere, they will be eroded into microparticles. If there is no atmosphere, should just sit there forever.

  • $\begingroup$ This. This already happened. Its nothing new. You just don't decompose. $\endgroup$ Commented Apr 25, 2018 at 15:12

This already happened in Earth's history

This question has a very simple answer. Read this article:


That is what would happen.

To summarize in case you did not read it:

There was a time in Earth's history when, for millions of years, you had trees that lived and died but there was no bacteria that could decompose them. This was because the trees evolved before the bacteria that broke them down.

What happens is that you get dead organisms piling on top of each other and crushing the earlier dead ones underneath. This compresses them into various natural resources that we use today (or in your case future intelligent species might use). You also get spectacular forest fires that last years or decades as there is just so much fuel to burn once a fire starts.

Adding a few dried up dead animals to the mix, I'm sure, wouldn't be any different than the piles of dead trees that existed in the past.

So what would you get? Oil, diamonds, fires, and some other resources.

From Wikipedia:


The large coal deposits of the Carboniferous may owe their existence primarily to two factors. The first of these is the appearance of wood tissue and bark-bearing trees. The evolution of the wood fiber lignin and the bark-sealing, waxy substance suberin variously opposed decay organisms so effectively that dead materials accumulated long enough to fossilise on a large scale. The second factor was the lower sea levels that occurred during the Carboniferous as compared to the preceding Devonian period. This promoted the development of extensive lowland swamps and forests in North America and Europe. Based on a genetic analysis of mushroom fungi, it was proposed that large quantities of wood were buried during this period because animals and decomposing bacteria had not yet evolved enzymes that could effectively digest the resistant phenolic lignin polymers and waxy suberin polymers. They suggest that fungi that could break those substances down effectively only became dominant towards the end of the period, making subsequent coal formation much rarer.

Reddit thread: https://www.reddit.com/r/todayilearned/comments/29jltf/til_on_earth_there_was_a_time_when_forests_didnt/


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