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My setting takes place in a post-apocalyptic america, and is in many ways a classic 'great war ends world' sort of thing. However, the cataclysmic ending to most of the country is persistent, lethal radiation that lasts way longer than it normally could from an atomic bomb. As such, most places are intact, and are made from high-grade materials whose frames don't decompose even after the timespan of 200 years, which is how long it has been since the war in this setting.

Because most of these people died from being irradiated, and in most places there are little to no organisms (except some radiotrophic fungus and bacteria), how long do you think they would last? I know climate is a major factor, but I'm essentially designing the setting across the country, so the climate can vary tremendously, and I'd like to know the answer for basically all of them.

I think this is a tough question because of how alien the concept is, but I'm hoping you might have some more insight than me.

user70449
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    Its not obvious how much of a factor climate would be, given the apparent destruction of most micro-organisms. Everyone would probably end up mummified. Realistically though, if you kill off all microorganisms and wait a few hundred years, I'd worry about anything, anywhere still being alive, and what the gas mixture of the atmosphere would be... – Starfish Prime Nov 15 '19 at 22:36
  • I should have been more specific and said that when I said 'most places' I really meant any population center. However, the devastation of the north american continent is ridiculously widespread; even rural locations are 'bombed' (more like fried) and even large stretches of wilderness are uninhabitatly irradiated.

    In many other places in the world the devastation is not quite as terrible, and sea microorganisms are still alive. Nevertheless, because the radiation is persistent in urban areas, they're still void of most life.

     – user70449 Nov 15 '19 at 22:46
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    The radiation levels to achieve your situation are spectacularly high. There would be no-one who could be around to find the corpses. Any visits would have to be very short. Only minutes, clad in considerable radiation protection garments. I agree with @StarfishPrime mummification is most likely. – a4android Nov 15 '19 at 22:47
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    Even with localised intense radiation, you'll have the problem of environmental effects either washing radiation into watercourses or producing radioactive dust which then blows away. It'll spread enormously, and be diluted as a result well within your 200 year timespan. I guess if you deliberately engineered super-long-lived, robust and heavy radiation sources and scattered them around you might get the effect you wanted, but it seems tenuous and you'll run into half-life and activity level issues, I'd have thought. – Starfish Prime Nov 15 '19 at 22:52
  • Well, the setting deals with some interdimensional tomfoolery. In short, energy devices have torn holes in the essential makeup of the universe, and used for such high output as a 'bomb' or lethal energy pulse, they make it even worse. The persistent radiation isn't from the 'bomb' or its residual, but from dimensional bleeding effects leaking exotic energy into the world, causing atomic destablization by fudging the basic laws of physics. The radiation actually does very slowly decay from weather effects, and by the time of the game, it is now safe to walk around in most rural or wild areas. – user70449 Nov 15 '19 at 23:01
  • @user70449 ahh, magic will do it, sure enough. – Starfish Prime Nov 15 '19 at 23:02
  • Similar? https://worldbuilding.stackexchange.com/questions/109950/everything-alive-in-the-world-dies-this-instant-without-bacteria-to-decompose-a – Willk Nov 15 '19 at 23:37
  • If it is "safe to walk around" then you may be certain that there are enough bacteria in the environment to feast upon the body... – AlexP Nov 16 '19 at 04:51

3 Answers3

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The most likely outcome is mummification.

The amount of fluid loss and shrivelling of the body will depend on ambient moisture, but the critical feature of mummification, the lack of decay, will certainly be present (on account of there being no suitable living microbes). They might potentially be very well preserved, though chemical changes to the dead tissues and fluid loss will make them hard to identify eg. via photographs. Fingerprints are likely to be intact. Even eyes might be intact in wet environments, though I wouldn't necessarily want to bet on that.

Bodies exposed to the elements are likely to be in a worse condition that those buried or inside buildings (or possibly vehicles) due to the action of wind or wind-blown debris, freeze-thaw damage, compression beneath heavy snowfall, large hailstone damage, dragging by water currents (maybe caused by heavy rainfall), waterborne debris, etc etc.

Alternatively:

Given the timescale of your story and the decreasing levels of radioactivity, the number of radiation tolerant micro-organisms is likely to rise significantly, especially if there's lots of preserved, ready-to-eat biomass just lying around ripe for the taking.

Consider the relatively short timescales that resulted in the evolution of radiotrophic fungi (unlikely to have been present in the biosphere before the refining and use of radioactive metals) and plastic-eating bacteria. It may well be the case that suitable fungi and bacteria will have arisen some time before the present day of your story, and everyone will have decayed as expected. Skeletons will likely still be present and intact where not exposed to the elements.

Due to the unnatural nature of your radiation, you'll have to handwave this one yourself.

Starfish Prime
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  • I think this makes sense - due to radiotrophism and/or radiotolerant mutation, they would still decay, albeit delayed. Thanks for putting a weird situation in perspective. – user70449 Nov 15 '19 at 23:20
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Everything would depend on the prevailing conditions in the location and the degree of decomposition required.

If bacteria and fungi are around a corpse would decompose to a skeleton in weeks to months depending on temperature in warm temperate conditions but might take millennia if the corpse was preserved by local conditions such as polar temperatures and ice.

Assuming bacteria and fungi are not effective due to radiation (unlikely) decomposition would still occur but would take a lot longer by chemical processes alone months to years perhaps but again it would be highly susceptible to conditions. The corpse might become dehydrated and mummified for instance and low temperature could prevent decomposition almost indefinitely.

High temperatures and damp conditions with plenty of oxygen would present the best option for chemical oxidation and wind/rain would also help dissolve and disperse the breakdown products.

Slarty
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This exact scenario took place in Ben Bova's Death Wave where a cosmic burst of gamma radiation instantly eradicated all life on a planet. If your only concerned about human bodies, the flesh will essentially dehydrate and turn to jerky while the skin turns to leather. Eye sockets will be empty as the eyeball shrivels to a raisin, with leather eyelids curled back inside. Lips and ears will shrivel a bit, getting distorted with teeth sometimes showing through. Over time the skin will turn black from the sun, slowly burning without being consumed. Hair should remain intact but will get longer, as will nails. The corpses will be 75% lighter than they were alive - very skinny and bony as all the water has evaporated. Clothing will show very clear fading on the exposed side, and bright colors on the underside. Nothing will be rotten, clothing won't be shredded or torn unless it's in the wind for a long time. Any plastic or rubber on their clothing, shoes, purses, wallets, etc will be cracking like an old tire.

As far as "all the climates," think of jerky and leather in the snow, jerky and leather in the sand, jerky and leather in the woods, etc. It will look like that. More sun = darker leather.

Vogon Poet
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