I'm considering the following scenario: Over the course of a couple of weeks, a global plague wipes out 99.999% of humanity, leaving just 75,000 people alive. These people are spread out evenly; in every regional and social group, only one in 100,000 survive. That means 14,000 people survive in China, 80 in New York City, and so on.

For these people to recreate the world, they would probably want to stick together. A society of 75,000 people is sustainable, since it includes plenty of doctors, engineers, and every other important skill. But if humanity is split up into tiny groups, scattered across the globe, long-term survival is questionable.

The question is, how would these people find each other? Global communication media such as the Internet and cellphone networks will shut down, and most survivors won't even be thinking about finding others until the plague is over. There will be a few surviving pilots, but they won't be enough to transport whole populations, let alone decide on where to go. Practically speaking, how will the survivors manage to join together?

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    $\begingroup$ As a side note, you should probably better leave a lot more people alive, since in the process of gathering together, many of them will die, because they have no experience at all in surviving on their own. $\endgroup$
    – PlasmaHH
    Commented Nov 7, 2014 at 10:20
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    $\begingroup$ @Pharap: Power will soon be off since people maintaining the infrastructure will cease to do so. $\endgroup$
    – PlasmaHH
    Commented Nov 7, 2014 at 11:57
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    $\begingroup$ sounds like The Stand $\endgroup$
    – Jimmery
    Commented Nov 7, 2014 at 12:44
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    $\begingroup$ You grossly overestimate willingness of the survivors to cooperate. In such situation, small groups (tribes) would compete for best resources. Device would be gun. See my answer why. $\endgroup$ Commented Nov 7, 2014 at 23:58
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    $\begingroup$ One way to improve the basic premise could be to, rather than assume that humanity silently let this plague destroy 99.99999% of the population, have humans make some effort to set up emergency services or meeting locations while it was happening, or spread info about how to remain in touch, e.g. notify public of emergency radio frequencies as it was happening. Otherwise the premise is that everybody simply sat around for 2 weeks until the survivors were simply evenly distributed, which is strange and not how I would expect humans to behave. $\endgroup$
    – Jason C
    Commented Nov 9, 2014 at 3:03

10 Answers 10


What made them survive and how long did the plague last? Answering this question will provide you an answer on "where the people will be when everyone else is dead." For time being, I am going to assume that Drax'es plan worked and thus the answer will be that the plague was quick (almost instant), global (so no remote tribes were left untouched) and you survived simply because there was flaw in the poisonous formula.

But still, random behaves strangely Even if one in 100 000 survived, it still gives good chance, that both you and your neighbor survived. The first survivors in my "quick poison" imaginations will be the luckiest one - meaning, they stayed alive in big pack of people on relatively small place (within plain sight distance).

What about the dead bodies? Do not forget, that if almost everyone died, there will be nobody left to burry the bodies. Even in slower "kill them all" scenario. As the plague progresses, there will be dead people lying on the streets and rotting. So, contrary to popular belief

Big city is the last place you want to go because you will see a loads of dead people lying on the ground, rotting - and thus polluting the area. Imagine the smell, imagine you wanting to stay here for longer time, because

If you want meet someone, you have to stay here So, if you survive in this set up and are, for example, in New York, you should

  • Go to Times Square (because it is most likely possible anyone else will have the same idea)
  • And keep here a sign noting in which direction you left
  • Leave city
  • And find closest farm or self sustainable living
  • $\begingroup$ I think a loud broadcast while you're there would help as well, not gunshots, but perhaps air horn blasts, or gunning a Harley engine (if you want to be stylish about it) periodically, for a few hours? In a world without people that would be heard for miles, and might draw people toward your sign, even if you didn't meet them immediately. $\endgroup$ Commented Nov 7, 2014 at 14:54
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    $\begingroup$ @JasonPatterson - Perhaps in the cities, but if you've been camping, you'd know that crickets can be loud. ;-) $\endgroup$ Commented Nov 7, 2014 at 18:18
  • $\begingroup$ @MrWonderful Have you been to a national park in the past decade? Unless you happen to be next to something like a waterfall or loud stream, you'll hear motorcycles. It's awful, and you can hear them from miles away. I've never seen a person wear earplugs around cicadas, but Harley riders do it not infrequently because their toys are so loud. $\endgroup$ Commented Nov 7, 2014 at 18:28
  • $\begingroup$ +1 for "What made them survive?" Any answer will depend largely on this. $\endgroup$
    – reirab
    Commented Nov 9, 2014 at 7:51
  • $\begingroup$ Nice transitions between points !! $\endgroup$ Commented Aug 4, 2022 at 20:52

I think this is a very interesting scenario.

If we look at the worldwide demographics, one can notice that half of the people on earth live in cities, half of those in cities with more than 500'000 inhabitants. (UN study) That means that one quarter of the people will find themselves in an area where there's a good chance to meet other people without too much of an effort.

For all the others, the most logical step would be to go to the next bigger city to find people. You should consider that not everyone will be able to do this, for various reasons such as them being too young or too old to survive on their own or simply because they live to far from a big settlement and might not have the means to get there. (Think remote islands). Some people might also just not think of it.

Now the question is whether all those 75'000 people will eventually meet somewhere common. In my opinion that's very unlikely. It is more likely that there are going to be small settlements scattered near the bigger cities. I would also say that after a while people will probably have to move out of the cities to grow food etc.

Once a settlement established, there are methods to communicate or reach out to other people with relatively low tech solutions. If you wanted to reach out to individuals you could use radio broadcasting, if you want to communicate with further away places maybe on other continents, you could use morse via radio, or also just broadcast your message via shortwave radio (This wikipedia page has an image giving an example of distances one can broadcast to in this way).

I think staying alive will definitely be the survivors first priority. You might be overestimating the numbers of specialsts for instance. Depending on the country, there seems to be between 1 and 4 doctors (with exceptions) per 1000 inhabitants. So even in most developed countries you will need around 250 peoples to have a more or less good chance to have a doctor and even then you might be unlucky and fall on a dentist or a psychiatrist instead of a GP. Even worse for pilots (US: 0.2 out of 1000), which should leave you with around 15 professional pilots world wide. Of course those are averages and the numbers will deviate.

Another issue would be the language barrier. You can see on this map from wikipedia, that there are many places on the Earth where only very few people speak English. And the same goes for other languages, so if you were to try to bring all those together in one place, most people would probably be unable to speak with each other.

The book "The Stand" by Stephen King explores a somewhat similar scenario.

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    $\begingroup$ Excellent breakdown, and +1 for mentioning "The Stand" $\endgroup$
    – Lindsey D
    Commented Nov 7, 2014 at 7:30
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    $\begingroup$ Satellites still exist, they just don't come spontaneously crashing down just because most humans are dead. Given that, global communication is still possible. $\endgroup$
    – SBoss
    Commented Nov 7, 2014 at 8:44
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    $\begingroup$ @SBoss That's true... I still think radio is going to more useful: it's a technology that is quite low-tech and that anyone with a radio device can catch. However satellite phones are not very common in most areas (as far as I know) and you'd have to know who you are calling and can't just make a general broadcast. I'm not a specialist though, so how would you use satellites in order to get into contact with people far away? $\endgroup$
    – drat
    Commented Nov 7, 2014 at 8:54
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    $\begingroup$ @PavelJanicek Depending on the duration of the plague, finding food and water could be trivially easy. Every person has a small city's worth of resources to loot; surely there are some canned beans lying around, or a duck in the park to shoot. $\endgroup$ Commented Nov 7, 2014 at 14:51
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    $\begingroup$ HF radio won't stop functioning, and allows long-range communications. There are about two million licensed radio amateurs in the world. That leaves about 20 licensed radio amateurs in your example. Add to that people who are familiar with short wave communications radio from other areas (including the military) and you can certainly have a reasonable number of people who know how to operate a radio. Finding each other would be a problem, but there are designated amateur radio emergency frequencies which would probably be a good starting point. $\endgroup$
    – user
    Commented Nov 7, 2014 at 20:02

Do they need to join together? What pressing urge would force them to overcome any hurdles in their way. As you described it, there will be many hurdles. It is very rare for a society to choose a hard route, simply because it's the hard route. Usually they try to find a smoother, easier solution.

If I were to let that scenario play out in my head, there would be an initial panic where NOBODY would be foolish enough to interact with anyone. Half of the survivors would probably get shot simply out of fear of being a carrier of the plague still.

However, once that initial panic wears off, human society has built in us the basics of how to form small family units again. From those, warring bands can form. From those, tribes. These conglomerations will not occur "just because," but rather they will occur exactly when it becomes beneficial to a group to do so.

Because of how few people per acre there are, foraging and farming would be valid solutions, even in New York City or Hong Kong. A small group of people could survive a markedly long time.

From there, it would just be a matter of time before these tribes settle down enough to have enough reliable food to start pumping children out (especially since they're good farm helps). Population would begin an exponential rise like bacteria in a virgin petri dish.

And then, at some point, they'd start running into each other, and trading stories. I wouldn't rely on technology or a flash in the pan idea to bring people together. A few million years of genetics has given half of our society the ultimate toolkit for reaching out and touching fellow civilizations. We've colonized the globe once, and I see no reason we couldn't simply do it again.

Accordingly, I would expect the strongest driver of re-connecting would actually be genetic pressure to avoid any small tribal group from becoming inbred.


Amateur Radio

Amateur Radio has been practiced since the inception of radio technology. See http://en.wikipedia.org/wiki/Amateur_radio for history and common activities. A brief overview of the kinds of things amateurs often do can be found here: http://www.ve3rhj.net/splitrail/whatdo.htm

Equipment is available on ebay and Amazon.

The US National Band Plan can be found here: http://www.arrl.org/band-plan. Pay particular attention to the frequencies or ranges called ‘simplex.’ That implies that it is for point to point communications, vs repeater work. The items noted as ‘simplex calling frequencies’ are where other amateurs would monitor when looking to make contact with new people.

You would likely benefit from a good quality scanner, in addition to several transceivers in HF, VHF and UHF.

If you prepare, you would want to stock 12V auto-type batteries, unless you believe you will be able to scavenge enough samples in the aftermath. Solar and/or mechanical charging equipment is highly advised as well — either in your own collection or knowing where you can scavenge panels and charge controllers.

If concerned, I'd recommend beginning the hobby now, so if/when the time comes, you'll have a clue how it all works in practice.

  • $\begingroup$ We're looking for answers that are a little more developed, not one-liners. The question points out that the power grid will be down, so how will radio be powered (including transmitters)? How will people know where in "airspace" to look and when? Please edit to develop this idea. Thanks. $\endgroup$ Commented Nov 7, 2014 at 17:25
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    $\begingroup$ Thanks for expanding this. While information is out there on Google, we're trying to build a Q&A site where the answers are here, not on the other side of links. So links for further information and sources are great and we don't want to re-invent the wheel, but we do want a little more, as you've now provided. Thanks. $\endgroup$ Commented Nov 7, 2014 at 18:46
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    $\begingroup$ There are about 700.000 amateur radio operators in USA - let's round it up and say a million people with the relevant expertise. In the proposed scenario, there would be 10 such people remaining across the whole country - most states would have 0. Still, after an initial gathering or re-grouping, this would be a reasonably possiple way to start long-distance coordination among a couple of the largest groups. $\endgroup$
    – Peteris
    Commented Nov 7, 2014 at 20:28
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    $\begingroup$ For those who have specific questions that are about amateur radio, rather than worldbuilding, head on over to the Amateur Radio Stack Exchange. We mostly don't bite (but make sure you understand the site's scope). $\endgroup$
    – user
    Commented Nov 7, 2014 at 22:17
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    $\begingroup$ @Peteris But both written knowledge and amateur radio equipment would be quite easily findable for decades after the plague, and quite a logical thing to look for. So I would say anybody with average IQ and ability to read could potentially set it up. It might be a challenge for a single person trying to survive at the same time, but for any group it'd be a plausible short-term goal. $\endgroup$
    – hyde
    Commented Nov 8, 2014 at 19:07

@Pavel Janicek is right. Random death is not orderly, and random clusters of under or overkill should be expected.

Another consideration is what exactly causes high mortality, or low survival rate. If survival is based on some very rare genetic difference, death will again be non-random, and some populations (sharing rare difference) would survive much better than others.

And quite possible that plague can also affect other mammals/animals. If so, piles of dead animal bodies would be not only in cities, but also in rural areas, and even rural areas would not be healthy/safe. Decomposed animal bodies would poison rural water resources, and because nobody is providing sanitation services, plague survivors might die of other diseases.

Also, with so few survivors so widely distributed, finding local expert speaking needed language will be very difficult. And transferring this knowledge to new generations would be very hard, because most population will have to work in low-productivity subsistence farming, with little leisure time.

Big part (20%?) of the survivors would be either too young, too old or in too bad shape to survive by themselves, and would die within weeks without help.

Another risk would be that one of survivors might by dangerous criminal, or power-hungry psycho. Need of cooperation between survivors is high, but competition for scarce resources would be intense and group cannot risk of allowing non-contributing person to join them. I think all responses grossly overestimate willingness to cooperate between survivors.

read http://en.wikipedia.org/wiki/Malevil . And that group had it good; they were a group of friends with established farm protected by a castle.

Survivors would form small groups (tribes) and compete with others for most valuable resources. Mad Max style. With nobody enforce any rules. Wild West. Tribe will be very selective to accept new members. Communication device would be gun. Hard to argue with. Contacting with new tribe would be rather risky.

Supporting industrial economy requires huge and very specialized human resources. Lacking these, economy will quickly revert to pre-industrial levels. With pre-industrial rate of survival. And pre-industrial rate of progress.

No electricity. Surviving machinery will fall apart within few decades, because replacement parts will be not available. After a decade, fuel reserves will be depleted, and no way to drill and distill for more oil.

Just FYI this similar scenario happened: Aborigines on Tasmanian Island had less developed stone technology than mainland Australia. Likely reason is that because of small population, groups could not support maintaining even those stone age technologies they brought from Australia.

With small population, any tragic accident has big chance completely eliminating all carriers of some knowledge, and it is lost.

It will be back to the medieval Dark Ages. With bicycles and scavenging old buildings, and old knowledge partially preserved, but close to Dark Ages.

One good place for survivors would be old castles, fortresses or other protected areas.


I don't think you need to worry too much about them finding each other because most of your survivors will die, and I think there is almost no chance that the number of survivors will assure the survival of humanity, even if they miraculously find each other. You need a much higher survival rate, which will affect communications and subsequent ability to find each other.

Approaching this only from a medical perspective, given your scenario (1 in 100K survive without restriction by genetics, age, location, etc. and loss of electricity/technology), about 12,500 will be aged 9 and under. Those under 5 will die in days from lack of water; those from 5 to 9 might live longer, but will likely die of disease, dehydration, exposure, malnutrition, etc. unless found by adults, so let's be generous and say 200 live and can someday integrate.

6,000 will be elderly (between 65-99) and will be well more than half women. While they will be helpful repositories of knowledge and can do light work, they cannot do too much, and their life expectancy will be dramatically reduced.

12,000 will be 10-19 years old. Most of those will have little skills or resources to stay alive (they will not know how to forage, let alone farm.) They, too, will be subject to disease and dehydration from unsanitary water and conditions (there are an awful lot of decomposing bodies around), and later by exposure. Being generous, let's say about one third will live more than 9 months. that's 4000, with about 2000 females. About 800 will be of reproductive age.

The golden number here is 28,000. That's the number of people alive between the ages of 19 and 45 (not inclusive). Half will be women of childbearing age. With the 10-19 year old surviving females, (14,000 plus 800) that leaves 14,800 women to repopulate the earth under adverse conditions. Of these, 2% will never conceive (296) and 10.5% will be unable to conceive after having one child (1,554) Of those who do conceive the first time (14,504), one in 100 will die from each pregnancy (the rate in underdeveloped countries) from postpartum hemorrhage, eclampsia, obstructed labor, and sepsis, (145 women) with the rate being 1 in 16 chance of dying from childbirth in her lifetime.

If all the females of childbearing age find males to reproduce with, after the first year of mating (not taking into account a spontaneous abortion rate of 20% before the 14th week), ~14000 babies will be born (half girls), 10% of the women will become infertile, and women will continue to die in childbirth: ~12930 women will be left for a second round. Miscarriages will increase due to decreased nutrition. Women will not have a baby per year in even the best of circumstances; the highest average number of babies per female in developing nations in the 1980s was 8.3. In the worst of circumstances, it will be much less.

In other disasters where a population was forced to become agrarian without technology (e.g. the Cambodia under the Khmer Rouge, after the initial killing of ~3% of the population, close to 25% of the population died in only 4 years (disease, starvation, overwork), and that was in a temperate climate. Your people have to travel to better climates by foot or animal. Think Oregon Trail. Mortality is very significant. A best guess scenario might mean the loss of about 3500 women in maybe 5 years, leaving ~9400 women capable of conceiving.

So, under ideal circumstances of every female mating every year, with the infertility, maternal death (and not even taking into account infant mortality, (which, as in developing nations will be significant), and an overall death rate of 20% in the first 5 years only, you'll be left with too few women and children to come close to repopulation.

If they are spread across the globe and must travel to find each other, the numbers shrink to a small fraction of the best case scenario.

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    $\begingroup$ "12,000 will be 10-19 years old. Most of those will have little skills or resources to stay alive (they will not know how to forage, let alone farm.)" I disagree. I think you're approaching this with too much of a developed-nation mindset. A large part of the global population still consists of subsistence farmers and they learn how to farm way before the age of 19. If I just had to guess, I'd guess at least half of the people in this age group would have farming experience. $\endgroup$
    – reirab
    Commented Nov 9, 2014 at 8:00
  • $\begingroup$ @reirab - You have a good point. I'm not sure, though, that the population of the earth is that favorably distributed. Interesting to think about. Even if you adjust upward in that age group, I still think mankind would not survive. $\endgroup$ Commented Nov 9, 2014 at 8:10

Much of the answer depends on the nature of that plague and the official reaction in the first days and weeks (cf @Jason C).

If 99 out of 100 people die in the first week, what will the crumbling governments do? Order everyone to disperse and self-quarantine? Will that order be followed? How long until a guy in a hut in the forest decides that he's really immune, and not just lucky until now?

Or is it a scenario where the affected people neatly crumble into dust one fine morning, or get beamed up by a passing starship? If 1 in 100,000 wakes up and finds everybody else is just gone, that would be more likely to trigger a search for other survivors.

With modern just-in-time delivery systems, cities don't store much in the way of food and other supplies, but remember how few people there are to use the remaining supplies. If most of the deaths come early, the survivors won't have food problems until the last tins start to go bad -- and "best before" dates are rather conservative.

To get back to the actual question, I would expect that some survivors actively try to find others. If they think it through, they will realize that a random search won't do much good. They'll go to local centers of government or landmarks and leave notes, as @Pavel Janicek pointed out. I think they might stay there a while if the remains of the 99,999 don't make that impossible. Get a car, drive around and honk.


I agree, amateur, or ham radio is probably the best bet, utilizing skip, but there is no reason for the internet not to still exist. Any IP using solar, or otherwise generated power and bouncing a signal off a satellite can be picked up and transmitted to anyone with compatible receivers, which, face it, there will be lots of, for free.

So, what would be required? A working IP, a satellite still in orbit, and they are programmed, they do not just fall down, and a recipient, and yes, satellite phones would work.

Other than that, look to carrier pigeons and pony express, lol.

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    $\begingroup$ I believe satellite phone calls are never phone-satellite-phone (I think it is a rare scenario both phones would even connect to same satellite), they are phone-satellite-server-satellite-phone. Or, at the very least, satellite would want to verify subscription status from ground before routing anything. So that would fail as soon as electricity failed. $\endgroup$
    – hyde
    Commented Nov 8, 2014 at 19:12
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    $\begingroup$ @hyde - When calling other sat phones, it does indeed go phone->satellite[->satellite]->phone without the need for any ground support. Also, according to our satellite carrier, all the account information related to billing status, is located onboard the birds. They say that if EVERYTHING collapses, you'll still be able to make calls to other satellite subscribers for a 3 month grace period after your account goes dormant. They also allow prepayment to ensure a longer service duration... $\endgroup$ Commented Apr 27, 2023 at 14:53

Depends on details... when power grid fails, that means no power for nuclear plants all around world, and many of them will meltdown because the backup generators ran out of fuel to keep circulating the coolant. (Used fuel generates lots of heat even when sub critical... nuclear plants in US have similar weaknesses to the disaster ones in Japan)

So you may have a bunch of nuclear reactors melting down after a few weeks with not enough organisation left to cap them after so still may have to live though a secondary radioactive waste disaster, and good chunk of people who survive the plague may die of cancer. As well, lots of those nuclear plants have lots of spent fuel stored in containers that will eventually sooner or later rust/fail without human maintenance.

Similar but smaller problem with some industrial/chemical factories... you can have tanks of hazardous chemicals just sitting there and eventually what holds them fails and they contaminate nearby air or ground.

As well, humans may not all cooperate, there can be conflicts over leadership, resources, directions, etc just like now. Anarchy/break down of social order is often nasty business, at least at first.

On plus side, resources such as solar panels and chargers, stored food, machines, etc may be plentiful, a smart group could carefully hoard stuff to have nearly modern day living standard for 100+ years even without the know how of building it. Eg horde a large supply of solar panels, when existing ones fail you replace with spares, similar with chargers. Batteries may mostly fail but not so big deal if you only mainly use electrical power when sun is shining... if you have for example 3000 watts of solar panels and inverter you can operate one 15 amp circuit of any sort of electrical appliance. With lots of spare computers, and understanding need one could have access to modern knowledge by accessing replacement computers for 100 years.

Possible you would have as result number of villages of 10 to 1000 people forming, and then like our modern world, possibilities of trade, merging, peace or war, etc. The people may not all group together which is both good and bad, on good side it helps avoid every human dying when the government makes bad decisions.

Easiest way for such possibly split up groups to talk is short wave radio, but not clear that everyone will want to talk, and not all groups will master it. It is often easier to make a living by salvage and piracy then it is to grow your own food, if you steal someone elses horde of food you have doubled number of years you don't have to grow your own, if you control the guns you can have easy life and others act as your slaves, in contrast the farmers who are have a horde of food, and know how to survive for 100+ years may wish to lie low for risk of being raided by the pirates.


Most of the answers are telling that you don’t need to focus on how to find each other, because (pick some):

  • Everybody is going to die
  • You should try survive instead
  • If you find someone he/she might try to kill you
  • You might not be able to speak the same language as the person you found

But these are not answering the question. Let’s accept that there are not problems in this case and address the real question: how to find someone in a mostly deserted world ?

  • Radio: already some good answers about this. On the bad side, you need power, and someone that is listening on the right channel at the right moment.
  • Very important: it’s not only about finding someone, it’s also about someone finding you!
  • Climb some tower or mountain and 1. Start a fire 2. Look for signals (especially at night)
  • Find a firework shop, take everything in your truck and launch a few of them every night.
  • Leave traces of your passage: Draw an arrow in the direction you are going, date it, and repeat at every turn you take. If someone sees one of your arrow, even one you left 1 year ago, he/she might be able to trace you up to the place you are now. (Think: painting, arranging stones, …)
  • Wear flashy clothes
  • Don’t forget to turn on every loudspeaker you can find, and in general to make as much noise as possible
  • Release helium balloons with messages
  • When you stop somewhere, make a smoky fire
  • Take time to look and listen to signs of someone doing the same.

So my strategy would be: travel from one densely populated place to the next one (higher probability of finding someone), leaving arrows and making as much noise on the way as possible. Once you start to gather a small group, divide and set a meeting point planned for a few month in the future. Once the group is too big, settle and send scouts, each time a little bit further.

Also I would look for patterns. Maybe the you survived because of luck. But maybe you have something different from the others? Does your family come from a remote alpine valley and have an uncommon gene? Did you participate in a medicine study for which you were inoculated with a later not released vaccine? If you discover a pattern once you found some other survivors, it might help to find even more people.

Let's go to that that alpine valley from where all our ancestors came from guys! Everybody is probably still alive there!


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