Imagine a world where every time you wake up you wake up in a randomly selected body from among the bodies that were asleep at that time. There are some limits—the body should be in at most a roughly 5 mile radius of the body you went to sleep in. People maintain their memories, personalities etc when swapping bodies—only the bodies change.

Could such a society function? It seems that cities on our current scale could not—since so much (jobs, rental agreements, etc) depends on relationships that would be hard to maintain with people swapping bodies so much. Perhaps a small society of maybe 30 people on an island could—since they all know each other and could maintain relationships, despite people hopping about.

The question: what is the maximum size society that could function under such an arrangement? What challenges could be overcome (and how) to reach such a size and what challenge would be the fundamental limiter preventing any further growth?


These clarifications mostly exist in the comments, but I'm putting them here to have them in one place.

  • Shuffling begins at birth and ends at death. If you shuffle into an old body that dies while you are in it, you die. If someone dies in their sleep, the mind that dies is selected randomly from the people in that region who were asleep at that time.

  • What determines shuffling is sleep: when someone awakes they get a random body from among the bodies that were asleep at that time (in their region). Time of day/night doesn't affect anything.

  • It is the minds/spirits that move during the shuffle. The body wakes up where it went to sleep.

  • Society developed in this way from the beginning. The question is not that if our society became like this could we cope, but if a human species had always lived with this context, could that species survive and how big could the population hubs be (e.g. small tribe vs town vs city).

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    $\begingroup$ Do you wake "in the body" as in, your body changed, or your mind passed to another body? Are you still in the same place you went to sleep in? Think it would change the answer. $\endgroup$
    – Nyakouai
    Commented Apr 19, 2019 at 13:35
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    $\begingroup$ Socialism might be quite popular. $\endgroup$ Commented Apr 19, 2019 at 14:37
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    $\begingroup$ there would be no society. My eyes do not produce the same signals as your eyes do. It would takes weeks or months to learn the hear with some else's ears or see with their eyes, in someone else's body you would have to learn to walk all over again, if it happens every night the human population is reduced to a pile a flailing sacks of meat. $\endgroup$
    – John
    Commented Apr 19, 2019 at 15:43
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    $\begingroup$ +1 for a unique question. I don't think I've seen anything similar here before. I did a light edit on your post to clarify some sentence structure things. $\endgroup$
    – Cyn
    Commented Apr 19, 2019 at 16:16
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    $\begingroup$ You may want to explore. Tragedy of the commons. For example: Why go to the gym, when you can drink and eat chips. Everyone would wake up fat and hungover. $\endgroup$
    – Nathan
    Commented Apr 19, 2019 at 21:10

17 Answers 17


Society as we know it certainly could NOT function if this were the case. A couple of issues that immediately occurred to me, even more fundamental than retention of property (and retention of property is huge!):

Children would be extremely dangerous to be around!

Adults are significantly stronger than children. Imagine if a mother and her one-year-old son happened to swap bodies. Suddenly you might have a one-year-old's personality and (lack of) wisdom in the body of a grown woman, and the mother in a helpless and weak body. The woman-bodied child might accidentally crush the child-bodied mother, or fall into a fire, etc. The mother would be physically unable to prevent these problems. Or imagine an angry four-year-old, still smarting from being told it was naughty to hit people, and suddenly in his father's body and capable of actually hurting people!

Power could be abused forever

Assuming the human race could survive at all... If proximity and simultaneous sleep could potentially be used to swap bodies, relative immortality would be possible for some. Enclaves could be established where only those of a moderate age and reasonable health were allowed to sleep, so the only body you would "risk" waking up in would be of acceptable quality. As someone "aged out", they could kidnap a young body, and lock the young body and the aging individual in an even more isolated cell for sleep-periods. When the locked-up kidnapped body can deliver the right password-type proofs that it's got the right person in it, you know the transfer is successful, and the old body may be eliminated.

Nothing like the world we currently live in would be possible.

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    $\begingroup$ "..., and the old body may be eliminated." Boy, that's a fascinating dystopian setting. I'd love to read a (short) story that expounds a bit on this idea. $\endgroup$
    – tomsmeding
    Commented Apr 19, 2019 at 20:08
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    $\begingroup$ @tomsmeding it would be the (more) twisted version of soylent green $\endgroup$
    – beppe9000
    Commented Apr 20, 2019 at 15:44
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    $\begingroup$ @beppe9000 or Freejack without the time travel. $\endgroup$ Commented Apr 21, 2019 at 2:33
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    $\begingroup$ @SamWashburn certainly worth experiencing :) $\endgroup$
    – beppe9000
    Commented Apr 21, 2019 at 11:51
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    $\begingroup$ @val Children, especially small children, wouldn't be very disciplined. Good luck telling babies when they can and can't sleep. And the elderly...have incentive to cheat. Then honorable elders die and cheaters survive? $\endgroup$
    – Jedediah
    Commented Apr 21, 2019 at 15:41

I actually think large cities could function but they would be very different to ours.

Your house would be near a cluster of sleeping rooms and would have a password entry since keys are not going to work. Clusters of sleeping rooms are at least 5 miles apart and probably need some excellent public transit options. That is probably the hardest part of making a city and is probably going to have assigned sleep times to help allow reuse. People would be assigned to these facilities based on age, gender, physical condition and so forth so you keep a similar body at least.

There would be numerous government centers that would give you a daily ID after you give a password so you can have an identity and legal agreements based on that. You have to show it to get into your job and you have to put its info into your phone to receive calls.

There will be huge penalties for sleeping in random places or at random times, as that threatens the system.

Children will be communal. Since no one really has DNA that is theirs and letting children swap with adults would be a disaster children will be raised in group facilities that are at least 5 miles away from any other places people might sleep. Being a parent will be a job like any other since little kids keep swapping around getting attached to any single one is harder.

Prison could simply be being stuck in disabled bodies, no matter how evil you are if you are paralyzed you aren't going to do much damage.

Coffee and other stimulants are practically mandatory if you are feeling tired while out and about so they will possibly be government dispensed. Health care is also going to be communal since one person's illness is now literally everyone's problem.

Immortality is possible and that changes things a lot. An old person just needs to set it up so they sleep with young people and boom they are young again. This could be the worst crime possible or a totally legal thing that's expensive but either way it would allow all kinds of radical changes to the world. Either way these cities could possibly have the same people in charge forever and that could help with stabilizing things against the chaos this causes.

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    $\begingroup$ And narcolepsy would be the most devastating disease :) $\endgroup$
    – Alexander
    Commented Apr 19, 2019 at 16:55
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    $\begingroup$ Taking care of the body one is in would be an absolutely key part of the culture. Looking at it from an evolutionary game theory perspective, there's an immediate benefit to not taking care of the body you're assigned- you get immediate upside, and the downside is shared amongst everyone. There would have to be incredibly strong cultural pressure to make people take care of their host body, or you get a tragedy of the commons situation. $\endgroup$
    – A Simmons
    Commented Apr 20, 2019 at 11:28
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    $\begingroup$ The immortality part might actually benefit scientific progress a lot. Imagine If Maxwell, Einstein, and other highly accomplished experts and scientitst could stay alive and keep contributing forever. $\endgroup$
    – user4574
    Commented Apr 20, 2019 at 13:12
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    $\begingroup$ These control methods may appear to be feasible with modern technology. However, part of the problem is also to explain how society could evolve from the ground up before the technology was in place.. I suspect that can't be brushed away very easily. $\endgroup$ Commented Apr 20, 2019 at 18:03
  • $\begingroup$ Nice ideas. Wouldn't it be cool to create a simulated society like this in a large computer and see how it develops. $\endgroup$
    – n00dles
    Commented Apr 21, 2019 at 20:55

Class Inequality You would likely end up with sectarian societies, one of which would be elites who create a "gated community" city that would exploit the labor of the lower class, but who would prevent those classes from accessing their community.

Religious Implications If their society is anything like ours, there would likely be monastical living situations based on a religious compulsion. People who shared these values would likely live as monks and nuns, since sharing bodies between sexes would be considered improper. Also, if there was something resembling a patriarchal power imbalance, men or women might not want the other to share in their experience.

Values This society, like ours, would be drawn towards empathy if not for the constant insistence on segregation of experience. Cultures that are empathetic would be ones that perhaps are not as technologically advanced, and therefore unable to travel the 5 miles to and from resources provided by others. The value of the individual would grow as technology advanced far enough to allow it to do so, and the value of community would be inversely proportionate to this.

Loophole You could consider creating the condition that the "size" of a person's mind (their experiences, intelligence, etc.) only transfers to a suitable host with a brain that allows for the same level of functionality. This would solve the problem of an isolated family. The mother and father might switch minds regularly, but the children might not until they had reached a certain age, and upon approaching adulthood, could possibly then switch with the parents. It would at least prevent a fetus from switching minds with its mother, which makes sense since a fetus' brain is not physically developed to the point of sustaining an adult's mind. This condition would also create some interesting characters--geniuses or those with broader experiences might be quite lonely waking up in the same body. The consistency of their physical appearance might make them natural leaders. In this scenario there would most likely be a group of leaders who wake up in different bodies but are consistently the same 10-20 people, revered for their experience and intellect. A twist to this story might happen when someone who doesn't consider themselves very intelligent suddenly finds themselves awake in the bodies of one of these elders.

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    $\begingroup$ I like the size-of-mind restriction. It seems to make things work more as expected. The Tragedy of the Commons problem is the hardest one to think around. You'd probably have a lot of government oversight, and would put offenders in a secluded prison, and drug them to make them sleep during visitation/adding prisoners hours $\endgroup$
    – Cullub
    Commented Apr 21, 2019 at 2:52
  • $\begingroup$ Ref. the Religious Implications: I don't think that genders would even have the significance they have for us, so religions discriminating or otherwise regulating things in that regard might be unlikely. $\endgroup$
    – fgysin
    Commented Apr 23, 2019 at 9:12

Answering this from the perspective of your world will be fun

It's easy to fall into the temptation of telling you about all the problems the real world would have if random body swapping suddenly began to happen. Let's not do that. let's assume that your world has been this way since the moment your sapient species became… well… sapient.

This would be nothing new at all to anyone. It would be a fact of everyday life.

Cooperative Breeding

Your society would most likely develop a behavior we humans call cooperative breeding. This happens when (a) the young of the group are cared for by all parents in the group and/or (b) when there are multiple mating males and females (no monogamy). From a modern legal perspective, it would be incumbent on whomever is psychologically in a household to care for whatever youth are found in that household for the day said parent is in it.

A species that developed this way would certainly develop a genderless perspective of individuality. Yesterday I was female, today I'm male... whatever.

Individuality would serve society

It is obvious to me that your society would need to embrace communal living, meaning that the resources of all are available to all. We humans have basically proven that we can't live that way, but where cooperative breeding becomes a requirement, socialized education, health care, provisioning for the child (housing, clothing, food, etc.) becomes mandatory.

This isn't to say there wouldn't be individual achievement, or even individual acquisition of wealth. Bank accounts have always been controlled by account numbers and pass codes. What would change are laws mandating that wherever you show up the next morning, you're obligated to continue with that household's efforts, whether they be repair work or anything else.

An astute observer will figure out that what I just described would be incredibly complicated. But, legally and socially, it could be made to work. Think of it as, "all your production goes to the state and we'll give you an allowance commensurate with your productivity and value to society." In other words; smart, educated, self-motivated people have a bigger allowance than those who are not.

Almost no housing would be private

In fact, I could be convinced that no housing would be private. The law would quickly change to reflect the fact that someone who was last in a beautiful, well-maintained home who suddenly found themselves in a wreck would choose to "let the next person deal with it." Wrecks would become condemned very quickly. Thus, no private choice in housing. Or transportation. Or almost anything else.

People would live very close to where they work

Employment would become password-based. As in, "I'm Bill Murray and I'm you're plumber! My password is Oscar-Delta-Zebra-Niner-Five-Seven-Seven-Epsilon-Eight-Zero-Alpha." This would require keeping great books with one person having the passcode to the door.

Which is all doable with modern tech, but how would the medieval folks do it? That's a good question.

The society would be ultimately trusting, with betrayers paying the ultimate price

Society could not possibly work without trust, especially early when technology couldn't make up the difference. And the only way that could possibly work would be with instant and merciless capital punishment. Though many might disagree with me, a society that can't trust fingerprints or visual identification (you look like Fred!) can't waste time with people who won't work with the community. It's not punishment — it's removal, like cutting out a tumor.

There is a weakness...

It would be very difficult to get anything done long-term. And by long-term, I mean two or more days. If your project is dependent on strong backs, then you need to re-hire your labor force every day because whomever the strong backs were yesterday, those bodies don't remember being the strong backs today.

Long-term planning (which is a big deal) would need to be carefully planned, incredibly well documented, and patiently completed. It could be done, but it would be slow.

And finally, death...

Your species would develop a behavior of segregating themselves by age. If you remember the old sit-com Dinosaurs, you should be thinking "hurling day." Without this segregation your society has massive problems (which others have pointed out).

However, from the perspective of a species, it's more likely that random body-swapping is something that wouldn't start before puberty and would stop in late middle-age or early senior years. So (to reflect my personal morality), 0-17 = no swapping. 18-60, swapping. 61-? = no swapping. Or, the swapping process is bound by age (you won't swap with anyone who isn't +/- 2 years your own age).


I think this could be made to work with any sized society. I do NOT think humanity could ever be made to believably work this way. The social upheaval would be catastrophic. But a species that developed this way. Yes, I can see that happening.

And it would make for a very interesting place for humans to visit.

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    $\begingroup$ humans are surprisingly resourceful. just remember not to fall asleep at work ;) $\endgroup$
    – adrian
    Commented Apr 20, 2019 at 4:07
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    $\begingroup$ @AdrianZhang, Don't fall asleep at work... I love it! I wonder if the OP's thought that through? Does everybody shift at midnight, or do you only shift if you fall asleep? $\endgroup$
    – JBH
    Commented Apr 20, 2019 at 5:59
  • $\begingroup$ +/- 2 years your own age: their body and your mind? Because otherwise, you could (de-)age up to 2 years per night, rapidly moving you to the limits of swappability. $\endgroup$ Commented Apr 20, 2019 at 11:36
  • $\begingroup$ @Deduplicator, Possibly. I don't know how to physiologically track the age of a mind. There may always be an element of unrealism in this solution. Statistically, it would be unbelievably rare for someone to keep aging backward (or forward), though not impossible. $\endgroup$
    – JBH
    Commented Apr 20, 2019 at 14:41
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    $\begingroup$ "... ...This would be nothing new at all to anyone. It would be a fact of everyday life." +1 Nice thinking $\endgroup$
    – n00dles
    Commented Apr 21, 2019 at 20:59

Assuming the switch only occurs while you are asleep, and assuming you want people to have private property it could go something like this.

Me and my neighbors all have a secure sleeping pod on the side of our house. I go to sleep in it every night because I know that when I wake up I will be in another pod and someone else will be in mine. I made sure to put all my valuables in my house before I went to bed. From the pod, the stranger will wake up, but they can't get into my house or access my stuff because the pod is not in my house. Usually they politely exit the pod and take a ride share back to their house (ist just a few miles).

Every new body has its quirks, but I have been in thousands of bodies before so I learn pretty quickly now. This one is very similar to one I was in last month.

The touch screen in the pod I woke up in has the ride share app on it. I also call for a ride. I pay the driver by telling him my account number. When I get there my wife is waiting for me in a new body. I don't really know what she originally looked like, but neither does she. I greet her and verify her identity by using my co-name (a secret name that is used only with another person or group) she verifies her identity by responding with her correct co-name.

I have different co-names I use with different people depending on how much I trust them.

I use my pin code to open my front door and get ready for work.

The kids are in a public boarding school. The school is outside the city so they don't switch with any adults. The teachers sleeping area is a few miles from the school. There are night time care-takers at the school to help children. The caretakers never sleep at the school. We Skype the kids during the week and visit them during the day on weekends.

We don't know who our kids original parents were. They are not biologically ours. And their minds are not from children who were biologically ours. But we adopted them when they became old enough to be able to understand their co-names. We had another child for a few months, but I think he was a bit too young when we adopted him. One day he stopped identifying himself to us and we never figured out how to find them.

I think this arrangement could allow a society to get reasonably big. But cities might be a little more spread out since you need separate areas for the children.

I think that one major change would be that the use of memorized access codes or account info would be more common since physical keys or cards wouldn't be useable after initially waking up. Also biometric identification would be totally useless.

  • $\begingroup$ "I pay the driver by telling him my account number." That's the place where ideas begin to be very weak. Passwords are easy to guess and 2FA would be totally impossible (your phone is separated from you every night). I seriously dobut that anyone would be able to remember anything 4096-bytes long to have private key/master password. $\endgroup$ Commented Apr 21, 2019 at 14:44
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    $\begingroup$ @val Passwords don't need to be thousands of bits long to be secure. Assuming the server run by the ride-share app could process 1 billion account requests per day. Then brute-force cracking a 9 digit password containing just symbols A-Z and 0-9 would take 100 years. Remembering a 10-digit account numbers is no harder than remembering a phone number. A password containing digits 0-9 and A-Z only that was 24 digits long would be equivalent to a 128-bit key. 24 digits is still within reason and there would be no way to brute force a key that long without a quantum computer. $\endgroup$
    – user4574
    Commented Apr 22, 2019 at 13:39
  • $\begingroup$ That also made me think: Despite technological advancements, people who want to secure their next wake-up would be in some acceptable healthy body-and-mind, and not a beggar in the street or other outcasts of society, would be very reluctant to travel far, so they would not sleep-over in "uncharted" territories. They would meticulously select with whom they travel, where they would sleep, and staying far from undesired people. Preparations would make travel and tourism costly, and not as popular as in our society. $\endgroup$ Commented Apr 23, 2019 at 7:24
  • $\begingroup$ Most likely society would try and find a way to make sure such people were not near the main population. Prevent such bodies from occuring via eugenics. Put the elderly in isolated retirement communities. Use the disabled to hold criminals in the prisons. $\endgroup$
    – user4574
    Commented Apr 23, 2019 at 13:37
  • $\begingroup$ @user4574, if you use a Diceware passcode, 8 words with some L33T-speak letter and number substitutes in there, the security level would be sufficient for the vast, vast majority of issues. I just generated "revival-same-punctual-boxcar-manager-handbrake-excursion-curtain" from an online generator. Change that to "r3v!val-same-punctual-b0xcar-mana6er-handbrake-3xcurs1on-curtain" and the security is pretty much unbreakable. $\endgroup$ Commented Apr 23, 2019 at 16:37

It would be very difficult for society to function correctly.

Imagine jumping into the body of a diabetic,someone with peanut allergies or any number of chronic medical conditions that an be managed by those that know they have them and what to do about it.

Randomly awakening in a body and not knowing that before breakfast you need to medicate or your new body will suffer serious consequences. Even something simple like eyeglasses without them a person may be unable to see properly, knowing where you left your pair the night before is important if your prescription is high enough.

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    $\begingroup$ Tatoo's. Lots of tatoo's. Important tatoo's go on standard positions of the body to alert that person. Normal routine would be checking the body's status, deficiencies and capabilities. Everyone also learns braille and sign language, because if you end up in a blind or deaf body that's going to be tough to learn afterwards. $\endgroup$
    – Demigan
    Commented Apr 19, 2019 at 18:10
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    $\begingroup$ And if you mess up and are dying, you inject yourself with a sleeping drug so that there's a chance you aren't the sleeping person whose mind dies when the body does... $\endgroup$
    – MarielS
    Commented Apr 20, 2019 at 2:32
  • $\begingroup$ You could work around these by saying that diseases stayed with the mind. It's a bit of hand-waving, but maybe eyes are ok; it's just the transmitters and receivers in the mind that can or can't process as well. $\endgroup$
    – Cullub
    Commented Apr 21, 2019 at 3:00
  • $\begingroup$ @Cullub but what of conditions such as diabetes or anemia that are nothing to do with the brain? $\endgroup$
    – Sarriesfan
    Commented Apr 21, 2019 at 5:17
  • $\begingroup$ @Cullub And what about forms of blindness that come from the physical structure of the eye, and not the brain? $\endgroup$
    – Zev Spitz
    Commented Apr 21, 2019 at 22:07

Current society? No, but I think that this type of system would actually promote people to live very similar, structured communal lives.

Imagine you wake up in someone's body, but that person didn't have any food in "his" house the day before. Now you go hungry, right? Suddenly it also dawns on you, how do you pay? Any physical paying methods would be on your previous body, and every time you go to sleep that would change again.

This means that every person would make sure the basics of life would always be available nearby, if only because if they don't do it someone else might also not do it. This would also mean that going drunk before going to sleep would be frowned upon, and people might actually be arrested and chemically kept awake until they aren't drunk or whatever anymore for the sake of whichever poor soul has to inhabit that person.

Communities would still be able to have their own houses and things, but the sleeping arrangements would all be located in one communal area. This way you know where you'll wake up, and after waking up you can move to your own house with your own things, live your life normally and then go back to the communal area's for sleeping. If this is how it's always been then monetary things might never really be invented. If it suddenly happens to our current world then we would try to use electronics to keep track of our money and to secure our homes. A memorized code can be taken with you when you go to sleep, the keys to your house and car can't.

Younger people would prefer not to wake up in an old body that is about to die or might never wake up. It is likely that bodies in general are going to get tatoo's to indicate when they were born, and thrown into one large group of similar age. These groups will always go to sleep in one area, away from other age groups. This way the group as a whole will grow old and die. There will definitely be people who try to abuse it and go to sleep nearby a younger generation group. This can be countered through a set of standard questions that each group gets upon getting up (easier when computer technology comes around), to see if everyone is accounted for. If someone from an older age group has managed to get inside the body of a younger age group he won't know the correct answers to identify himself as a specific person from that group and a search will happen for the person who does have the correct answer, after which they are forced to swap back again.

This communal thinking will have to stretch to everything, including children. If you get knocked up one day, you'll have a good chance you'll never even see your own pregnant body again! Children would have to be raised in communities as well, as there's no real telling who is the mother or father. The person who finds out if you got knocked up is going to be inhabiting it months down the line!

  • $\begingroup$ No one spoke how mentally-retarded persons would be dealt with. What happens to the memories in your former self in this regard? Would you be able to understand what you remember from former self. How wou you deal with this? You would probably isolate populations based on that as well, and not only age. $\endgroup$ Commented Apr 22, 2019 at 14:22
  • $\begingroup$ @ChristmasSnow that depends wholly on how the swap happens. If you inherit the brain architecture of your host than your intelligence, capability and even personality would change drastically each time you switch. I expect that such drastic changes wont be present, so mental disabilities would travel with the host, barring extreme cases like split-brains and such. $\endgroup$
    – Demigan
    Commented Apr 22, 2019 at 16:43

Of Course We'll Still Function!

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No one has actually changed...not where it matters, anyway.

Of course society will be quite different. You never know what you're going to look like in the morning, so neither you nor anyone else really cares. You don't know what your coworkers or friends or anyone else is going to look like, so such visual social cues will be nonexistent.

You just wake up, say good morning to whoever is in the bed / sleeping chamber with you, dress in whatever clothes are locally available and go about your day already.

Leave the existential breakdowns to the philosophers, because you've got to get downtown for that meeting / get over to the public works depot and sort out that issue with the rubbish truck / get to the shop and make the donuts.

  • $\begingroup$ People do care about others specially their children. If the parent is 5 miles away who is going to make sure they are alright and doing what they are supposed to like going to school? $\endgroup$
    – Anketam
    Commented Apr 20, 2019 at 17:34
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    $\begingroup$ We care very much, yes. I'm not talking about us, Our job is to imagine a world where this already happens. Clearly, our kind of society can not happen there. It will have to evolve quite differently. Obviously, people in this kind of world will nòt care about their own children. Children will have to be cared for more corporately. There will be no "mama" no "dada". Whoever is available --- whoever wakes up in the immediate vicinity --- is responsible for the children. $\endgroup$
    – elemtilas
    Commented Apr 20, 2019 at 19:05
  • $\begingroup$ What do you do about the fact that toddlers are notorious for getting themselves hurt, and the day they swap with someone in an elderly body they will most likely die. For example trying to cartwheel down stairs or do a flip off a couch. Now all the young souls consistently kill themselves and we have only old souls. Also how do you address impersonators and frauds, given that there is no way to ID people, and if a member of your committee dies you probably will have no way of ever knowing. $\endgroup$ Commented Apr 22, 2019 at 13:26
  • $\begingroup$ Evolution in action. $\endgroup$
    – elemtilas
    Commented Apr 22, 2019 at 15:25

Jack Chalker seems to think that it might be possible - he postulates a similar society in the second book of his Four Lords of the Diamond series, Cerberus: A Wolf in the Fold.

His society is somewhat more controlled than most modern societies, and has a method of identifying a person mentally - that is, the mind that's in the body. In general, there are two classes of person - those that keep the same job regardless of the body they're in (i.e., the job stays with the mind), and those that keep the same job regardless of the mind that's in the body (i.e., the job stays with the body). Most white-collar jobs are in the first class; undesirable jobs, and (in his society) host-motherhood, are in the second, and it's rare for people in the first class to associate with people in the second (because what happens if a first-class swaps with a second-class?).

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    $\begingroup$ Beat me to the punch. $\endgroup$
    – EvilSnack
    Commented Apr 20, 2019 at 3:47
  • $\begingroup$ Also note that in Cerberus bodies of greater than a certain (unspecified) age are shipped off planet so none of the current generation has to die - giving practical immortality to people who are politically correct (those that do as they are told). Babies are kept away also, because who wants to be reminded that those babies will be put in the old people's bodies and shipped off to the moon. $\endgroup$ Commented Apr 22, 2019 at 14:21
  • $\begingroup$ Also note that in Chalker's series swapping range was a few meters and could be stopped with lead curtains. On his world space-faring humans arrived and they were given this ability, (but they could no longer leave the solar system) society did not form there (in the sense that you mean it). $\endgroup$ Commented Apr 22, 2019 at 14:25

There would be no society, there would be no humans.

My ears do not produce a signal your brain can use to hear, not without months of exposure for your brain to relearn to interpret the new signals. Brains are not interchangeable they have to adapt to processing the signals of the new body. Based on flipped/inverted glasses experiments it would takes weeks or months to learn the hear with someone else's ears or see with their eyes, in someone else's body you would have to learn to walk and even control your muscles all over again, if it happens every night the human population is reduced to a pile a flailing sacks of meat, unable to control their bodies well enough for coordinated movement and unable t o understand what their sensory organs are sending. billions would die of starvation or exposure. Within a few weeks of the first switch there would be no humans left.

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    $\begingroup$ Meh, this could be hand-waved. It would be a problem scientifically today, but we're dealing with a society different than ours, where they switch. Let's assume that the eyes can still hear and ears can still hear. Etc. $\endgroup$
    – Cullub
    Commented Apr 21, 2019 at 3:04
  • $\begingroup$ At that point you are not switching anything but a few memories., if you are switching the vast majority of your life experience with the person then you are not really YOU anymore. $\endgroup$
    – John
    Commented Apr 21, 2019 at 13:52
  • $\begingroup$ The brain and all its neuron connection stays with the body. Only consciousness swaps. $\endgroup$
    – arp
    Commented Jul 26, 2019 at 21:03
  • $\begingroup$ @arp your consciousness is your neural connections you can't switch one without the other. That's like saying you switch the contents of a book but none of the words swaps. $\endgroup$
    – John
    Commented Jul 27, 2019 at 14:02
  • $\begingroup$ @John I don't think that aspect of reality can come along to this scenario. $\endgroup$
    – arp
    Commented Jul 28, 2019 at 2:32

The statement that society has always been this way puts a hugely different spin on this. What you grow up with is normal and a race that works like this will have no problem with it. But society will develop very differently from how human society did. We can consider how early societies functioned under these circumstances, as that will dictate how later ones work.

Early societies were isolated clans, so it is likely that initially transference took place only within your clan. The needs of survival mean that early people didn't think about it or spend much time concerned with it. Personal property probably never became a thing, nor did monogamy. You might well keep the new mate you woke up next to for her body (her mind and personality are secondary) and who does the knife lying by your bed belong to anyway? Sense of self probably diminishes too, and since random personalities likely die occasionally people don't get attached to the idea of life.

All property becomes clan property. Children become clan children, since the problem of figuring out which personality is actually responsible is far too complicated for a group focussed on survival.

Fighting would be virtually unheard of within the clan. You might slap someone you disagreed with, but you would not damage a body you might inhabit tomorrow. Bodies would be considered common property, and the clan wouldn't let people mistreat them, either while inhabiting them or not.

There would be no segregated roles. You wouldn't leave your most knowledgeable hunter out of the hunt just because she happened to be female today. Likewise nobody can use strength to dominate another person or group, since they might be the weak person tomorrow.

Territories would be strongly defended. Conquest and slavery would be unheard of. You cannot keep anyone is slavery if you might wake up tomorrow in their physical circumstances. There might still be war, where one clan attacks another to gain possession of something like a natural resource, but it would probably be necessary to kill all the previous inhabitants when you did so. There would be no kings or power structures for the same reasons.

Visitors would be limited to daytime unless well trusted because of the possibility of leaving with clan property, including but not limited to a valuable body which might be better than the one they arrived with. This would make trade extremely difficult. Ancient society evolves into networks of clans, separated physically to prevent intermingling but trusting each other well enough to allow occasional visitors for trade and similar purposes.

In these circumstances it's hard to see how civilization evolves into large cities (even large by ancient standards, i.e. a few thousand people). This effectively prevents the imperial conquest phase of human evolution from happening.

it's also hard to see how specialized labour can happen, which might prevent the rise of the leisured classes which give rise to scientists and philosophers. This along with trade problems might slow scientific and economic development.

  • $\begingroup$ "You cannot keep anyone is slavery if you might wake up tomorrow in their physical circumstances." Not so. Note the premise: people switch with someone who is asleep at the same time, and there's a distance limit. As soon as that's figured out, you're going to have your slaves only allowed to sleep at a distance from the slave-owners, and the overseers/guards will work on shift so they're not sleeping near the slaves either but instead commute in. $\endgroup$ Commented Apr 23, 2019 at 16:45
  • 1
    $\begingroup$ I knew somebody would suggest something like that. But it's a lot of effort. It might be the amount of effort you would put in if you already had slavery and wanted to keep it, but not the amount of effort you would put in to invent a new way of doing something. And being a guard is a high risk strategy - fall asleep once at your post and suddenly you are a slave. $\endgroup$ Commented Apr 23, 2019 at 19:59
  • 1
    $\begingroup$ Never underestimate the lengths some people will go to be dicks to other people. And in any event, it's not worse than the way they're going to have to deal with prisoners. $\endgroup$ Commented Apr 23, 2019 at 20:21

While thinking about "how would it fit into modern society" is fun, what if we'll think about development of such species from ancient times?

Ancient times (humanity begins)

So here we are, small (let's say 4-15 person) groups who recivied souls (somehow). Which problems such group will likely face?

  1. Bodies may vary.

Yesterday you were able to go hunting, today you are much better at looking for babies and harveting berries. I have no idea about their psycology at that times, but idea of being genderless is likely: whatever, it is just process of creating children, no hard feelings. Monogamy is very unlikely too: it is not profitable for surviving anymore (if sex is still about biology and not souls, otherwise entire humanity will work different way starting from this point).

This also leads to learning of everything known regardless of anything: person should be able to use any body at its max abilities.

  1. Children problem.

As other answers have pointed out, children are dangerous now. Let somebody wake up in their body and they are useless for a day. Let very young baby wake up in adult body — they are useless again but also posess a great danger to others.

This could be solved by never sleeping at same time children do. Hopefully, your day still have around 24 hours and your fellow humans need about 8 hours of sleep everyday. In this case we can divide day into two part: 15-hours one for adults' sleep (exact time may vary, also different people may enter and leave sleep during it) and 8-9 hours when all adults don't sleep and children do. We also now have somebody awaken to keep an eye on your children to don't let them fall asleep.

Moving into adult-time sleep may occur in specific age or when one is skilled enough to do something useful. This include some interesting rites tho…

  1. Elders and deathly ill ones problem.

Things turn out sad this time. When some body becames too weak it will be better for spiece to get rid of it by exiling or even directly killing them. But who will take it to die within? It could be one of that: random unlucky person, somebody least useful (good for spiece 2x) or some children.

Why children you say? It will allow to maintain knowledge easily, without need to write down or even talk… and never develop speech nor modern society. We just hit dead end. Such society will exsist and will likely be found by researches in distant future ("Scientists have discovered group of persons whose souls must have seen 10000 years BC" - BBC from your world).

So some groups decided to put only full aged ones in elders bodies and force them to go away to die. Reason doesn't matter — some randomy appeared rite would be enough.

Also, rite to keep your todays' body in great form will be required because group will die really quickly.

Before/medival ages

Let's say at some point our last group develop speech and have to face an important problem: technologies became too complicated to be perfected by everyone and profession may require different body variations. What to do now?

Easy and efficient solution would be to let different masters live in separated villages/towns where exchange of souls is impossible. In order to exchange stuff they will have to meet in some kind of special place like giant market where all kind of buisness do occur: it also may include some common education schools. Some persons who wish to change their lives may also sleep there to exchange bodies with others from different towns. However, it will likely be punished by others due to requiment to teach them again, if they aren't children (which now have a way to get body sutable for profession of their dream!).

This model also may lead to some fun evolution where different towns develop their own different DNA samples (each town is a distinct population actually) resulting in specialized farmers, blacksmithes, miners and others, probably even ending in ones who differ a lot if this epoch lasts long enough.

As for government, it is not very likely to have one (and much harder to have more than one). Wars would became something insane due to constant exchange of bodies.

Such society will require strond punishment for betraying/cheating within one town, or it will fall apart. This require absolute trust at first, which potentially could be maintained on long term too. Religion would help a lot.

And to our older problems:

  1. Bodies may vary.

Nothing pretty much changes. Everybody in town is married by everybody, everybody master the same thing.

  1. Children problem.

And we still have same solution. Other one is impossible until we have a way of isolating children from overwatchers (while keeping them alive).

  1. Elders and deathly ill ones problem.

And here we have some positive changes: elders from different towns may live in separated one, helping each other. While it is still doesn't seem so great, it is at least sounds a bit more accepable, huh?

You have a great idea which nobody seems to implement yet? Well, we are in trouble here…

This society is very stable and can change hardly: pesonality is not valuable here, congrats on building communism. It may last many centuries or even few thousands of years until somebody comes to change it…

Technological revolution

It is impossible to say how exactly will it begin. Probably, someday some crazy person finds enough followers on giant marketplace who agree to join him on everyday base is some crazy project like steam engine or something else which will knock the world over. I'm not going to describe it completely here (that would be interesting story to read for me tho), let's say that humanity begins to belive into innovations, and this means a lot. Some people begin to leave their towns to join new village of researchers… which probaly became rich pretty soon!

Futher development

There are some critical things which could change your society a lot:

  1. Automated machines which can take care of children. They would allow to finally escape childrens problems and use humans much more efficiently.
  2. Shuffle inhibitors. If somebody manages to invent them and produce in huge portions, they will be able to insantly overcome a lot of complications, making it possible to build stable group which could became an army capable of acting hightly organized and capturing cities with ease. This may lead to a very long way to something like our society either in case of war or making them publicly available.

If last one don't happen, it is possible to survive within realtively small towns and without government: things like private property became impossible because you can't remember anything not guessable within reasonable time and there is no way to do 2FA. Of course, until you have

  1. USID — unique sould ID.

If there is a way to confirm that some body have somebody's soul, it becames possible to build all kind of advanced things we have. It will can not lead to any kind of war, making it possible to migrate into large low-trust cities where it is possible to mantain all kinds of property and access restrictions.

People will likely have something like "house", place where they can enjoy their favorite private things like videogames, and public bedroom qarters, where everybody sleep. Rich guys may build houses in distant places, trying to keep same body for long time.

Machines which can automatically take care of children and elders would improve situation too. As replication was never considered somewhat really private, when tech level reaches big hights making it possible to grow children from scratch without having sex, it will likely eleminate old way, especially if being supported by government.

Everyone in cities will be entrusted with keeping their current bodies within reasonable state to keep every body healthy. Health will likely be tracked every bed exit/enterance, noting body vandalism and writing out fines from such souls.

Medicine will be kept by government because bodies aren't private property at all. Ones who need long-time recovery could be moved into distant machine-operated hospitals as well.

Non-mental contests will likely never became popular or even existent — it will seem clear for everyone that bodies is somewhat unimportant in their lives.

Prisons will likely be distant machine-operated places as well — you don't wanna let criminals escape via soul exchange!

As for elders, it is hard to say to which morality that society will attach. It seem reasonable to make criminals take old bodies to let good people use healthy ones.

Overall, future doesn't seem to dark anyways. Body shuffle works nicely in two cases:

  1. Small society with absolute trust. This is also applicable to space expeditions in modern word.
  2. Big society with SoulIDs.

So answer depends on ability to get SoulID: if you can, huge cities with modern technologies is possible, if not, small towns still can survive quite happily. If it is possible to inhibit body shuffle, result depend on when they discover it: it will lead to catastrophy in medival times but can be used in quite good ways if discovered in modern world.

  • 2
    $\begingroup$ Good point about the having children. If children are still biological, you could be the mother of your child one day, and then not the mother ever again. Meanwhile toddlers that are notorious for getting themselves hurt can appear in an old person's body, try to cartwheel down the stairs and die. It seems like the old souls would survive forever, and the young souls would all kill themselves off. $\endgroup$ Commented Apr 22, 2019 at 13:23
  • $\begingroup$ We seem to be working on the same lines. $\endgroup$ Commented Apr 22, 2019 at 13:49
  • $\begingroup$ @DJClayworth Yep, seems like my "Before/medival times" section overlaps with your answer a lot. $\endgroup$ Commented Apr 22, 2019 at 13:54
  • $\begingroup$ And when I got time I was intending to expand my answer into later history. $\endgroup$ Commented Apr 22, 2019 at 13:56

Vault 93 - OVERSEER'S EYES ONLY - example exposition:

Good morning, citizen. Today you be inhabiting, [name], of sector number [#]. Your responsibilities will include but are not limited to: clothe, feed, and ensure the attendance of any students under your care, prior to 9am. You will report to work at facility [#] for [amount] hours. After which you will feed, launder, and otherwise ensure the health of family [name] of sector number [#].

Failure of any of these responsibilities will result in lower marks, and your next inhabitation will be less desirable to suit. Desirability is determined by exit interviews which occur just before bedtime.

  • $\begingroup$ I feel like it would be an interesting idea overall, but "Failure of any of these responsibilities will result in lower marks, and your next inhabitation will be less desirable to suit." assume that there is a way to somehow control shuffling process. $\endgroup$ Commented Apr 22, 2019 at 16:33

My guess is that it will not work with our kind of minds, which needs years of teaching (in growing up, going to school, studying and so on) before being able to hold a good job. Simple jobs for many people would work but besides those simple jobs you need harder jobs, where training and study are important.

But it would work with a community where the minds are like some animals which have a good working set of instincts and can learn on top of that.
If babies do not need parents to feed them but can find enough to eat around the nest/home they can grow to become useful members of society. If you look at some birds, they have the basics of surviving from birth, learning from copying others when they see those do something smart.

To get from a hand to mouth, gatherer (and maybe hunter) society to a farming (or herding) society will not be easy, but it might help when groups of people stay together and not mix much with other groups, so people are more likely to learn to invest in the future.

Going from that to a more technical society and on to a mechanized and on to an industrialized society will be much bigger steps that they were in our world.
A lot will depend on how much experimenters the people are, which is a decision you as writer has to make, and what kind of muscle memory (stays with the body) there is to build on what the body has done before.
And how big the groups are, if your average swap group is no bigger than 7 people, you would be in the same body on average once every week, which would be good enough to encourage people to work for the future, certainly if it is a common future. But if the group size is roughly 350 people, you only end up in the same body (on average) once a year, if everybody swaps with everybody.

My guess is that in the early developments, from just gathering to hunting or farming/herding, you need very small groups, basically extended families of no more than 10 to at most 20 people. For the further developments you need bigger groups but not too big, maybe a few small groups staying near each other but just out of swap reach, say 30 at first and going up to 300 in split groups, (still no more than about 10 to 20 for swapping) for getting crafts and early mechanical developments.

Only when you have that level, you can work out whether they can start live closer (small towns/cities) with all the swapping or need smaller clusters for some age groups (called boarding schools in an other answer) or that society can develop in your kind of world in spread out villages (smaller groups.)

What will help is if individuals usually have quite long lives and as such a long time to learn and share knowledge.

  • 1
    $\begingroup$ Interesting idea. Society in smaller groups would lead fairly naturally to a guild style concept. For example, all the blacksmiths would sleep near one another, that way they'd all wake up in another 'blacksmithing' body the next day and they'd be far away from the joiners and the masons and so on. The muscles have the muscle memory and the mind has the skillset to use it. A person might not be that specialised, but a group would be. $\endgroup$
    – Greig
    Commented Apr 21, 2019 at 15:54

Not a complete answer but something I don't see in any others.

If you are close to death, and have the resources for medical care, then you just get put to sleep. You have at least a fighting chance of waking up in another body before your old one dies.

This leads to another question - if a body dies while asleep, who dies? The person who did inhabit it? But maybe they have been already assigned to a new body? If that's the case is there now N+1 souls hanging around with N living bodies? Does one wake up dead, or do they all wait for a body to be available, with an equal chance of getting reincarnated when the next body wakes up? That would lead to an eventual accumulation of disembodied souls as more people die in their sleep.

  • $\begingroup$ Per the updated question, a death is chosen randomly while sleeping. $\endgroup$
    – Cullub
    Commented Apr 21, 2019 at 3:09

This is basically a recipe for living forever.

People swap swap swap, but as long as your body doesn't die, you won't die.

I can certainly see this as a society killing off their young(minds), just them being there providing new healthy bodies.

You would have baby farms, far from populated areas, staff would not be allowed to sleep. Old bodies would go there and pickup a baby to take to retreat so far away from everything else, that there is only 1 swap possible. They go to sleep and now you have a baby in an old body and get rid of it and the other person lives on.


I can see it ending either in a good way or bad way


The constant body swapping made everyone realize that we should strive to take care and love each other above all. No one should be left behind since that no one could potentially be you.

War and greed end, everybody shares resources for the greater good. Humanity's efforts are focused on good things, curing diseases, extending lifespan, making sure everyone has a happy healthy life. The mysteries of aging, organ systhesis and intergalatic travel are eventually solved and everyone can live forever. Humanity spreads spreads through the galaxy.


Criminal organisation leaders quickly realized that if they manage to gather a pity of healthy strong prisoners and only sleep in their vicinity, you would always wake up in a young body and be potentially immortal.

After a wave of high profile kidnapping (high level athletes, models), Billionaire started offering vast amounts of money to healthy young people who would join them and had no problems ensuring their immortality without resorting to any illegal means.

Celebrities and political leaders and other high profile people had no problem finding volunteers, their fame guaranteed that. For the rich but not super rich, it would be more difficult to be immortal through this process but not impossible.

Gradually society changes and everyone's only goal is to find a group to guarantee their immortality. Body shuffling collapses society, Chaos and war follow and eventually the world becomes a totalitarian dystopia whos only goal is to maintain immortality for the upper castes.

A vast majority of humans would just be kept in a vegetative state as spare parts. The lower classes have to toil to run things. To prevent constant revolts, the hard working ones are sometimes upgraded to a higher caste. If you rebel, you are "shut off" and kept in a vegetative state or worse, your organs are harvested.

Women are a very precious resources and they are treated as cattle, forced to breed as soon as they can until their death. The productive one who produce than 10 offspring are offered a caste upgrade. Babies are the primary resources for immortality after all.

Society stagnates as the immortal elite eventually degenerates after centuries of hedonism. Humanity never goes to the stars and the next planetary cataclysm (metor strike, giant volcano, ice age) wipes out humanity.


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