Our civilisation is capable of creating any life form we're finding on alien planets. We "sample" several subjects by abducting them and we study them. But for some advanced species, for example - humans - it's not enough. Humans are an interesting example of "social-featuring" species. As such, we can only understand them when the subjects live in their society.

For that matter, we can create new specimen and then release them into societies of their domestic planet so then we can observe those. Question is - how many can we release into their society before their governments will notice?

What we can/cannot do:

  • We can create a specimen of any age
  • We can not "copy" memories from another specimen (unfortunately, it turns out that memories are on a quantum level and.. well, no-cloning theorem prohibits such cloning)
    • In particular, we struggle with memory manipulation in general, because - eventual consistency. If we "change memory" for someone, at some point it will inevitably contradict with their other memories derived from other events leading to the risk of mental deterioration. We want to avoid this.
    • EDIT (thanks to @Alexander): if the memories do not cause eventual inconsistency - we can implant those. For example, their name, a language or a profession.
  • We can create as many of them as we want

As such, our new specimen will not have any memories and obviously, will not have any of those weird things they call "documents". We want to have as many of our created specimen at the same time as possible as it speeds up the research and, you know, the research budget isn't a thing that comes easily.

We already consulted with our colleagues on a similar problem here but we're facing a problem from the opposite side.

  • $\begingroup$ Interesting question! To clarify: these humans have no memories at all, and won't know anything about society? Or like, how to feed themselves? $\endgroup$
    – Dubukay
    Aug 28, 2019 at 15:40
  • $\begingroup$ @Dubukay Reflexes? Not a problem. Also, we can implant basic memories. But if we do so for an adult specimen, they will have questions like "who am I, from where am I?" and so on. They will ask around and likely reveal that they are at least not normal human - and certainly won't be good observation sample. $\endgroup$
    – Alma Do
    Aug 28, 2019 at 16:11
  • $\begingroup$ Do you dump adults or babies? If adults, would they be essentially amnesiacs? $\endgroup$
    – Alexander
    Aug 28, 2019 at 16:41
  • $\begingroup$ @Alexander it can be adults or babies - doesn't matter. If we conclude that's we have better chances and can release more specimen by releasing babies - we do it. Again, we can create a human of any age $\endgroup$
    – Alma Do
    Aug 28, 2019 at 16:43
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    $\begingroup$ The memory issue is not actually that big a deal. Human memory is very plastic; it changes over time, and people can remember things that never happened, remember things that happened differently, and forget things that certainly happened. Having memories that conflict isn't a problem because odds are the memories will conform to each other to form a consistent whole. $\endgroup$ Aug 28, 2019 at 17:48

6 Answers 6


All depends on which segment of society needs to be penetrated.

If new humans would know that they need to stay "under radar" and have some skills to do so, you can dump millions. Both US and Europe now already have millions of undocumented migrants. If the new people are designed to blend in with this crowd, it would be a while before authorities would suspect that there is some problem which goes beyond just "migrant crisis". As a "guesstimate", you can dump up to 1% population this way (about 3 million for US).

For homeless population, numbers are lower, but still impressive. Probably 0.1% of population (about 300 thousand for US) can be added that way before the plan is detected.

Penetrating higher levels of society is harder. In modern developed countries, getting documentation is not easy, and authorities would go through a lot of scrutiny before issuing new documentation. No more than 0.001% of population (about 3 thousand for US) can be added before authorities will see some red flags.

Somewhat easier would be to add babies and senior adults. It is more common for seniors to be found with patchy memory and no documentation. And babies, naturally, have no memories yet. You may be able to add as much as 0.01% of population (about 30 thousand for US) in these segments.

P.S. This answer is assuming that dumped people are not aware of the aliens' plan and do not conspire with each other to make it succeed.


Placing babies is very feasible (no memories), and you can learn human society as you watch humans raise them. It is hard to come up with info on "abandoned" babies, but it looks like a few hundred per year in the US:
So you can probably plant ~100 babies over a year, scattered across the nation.

Planting adults might be a bit easier. Plenty of homeless people have mental conditions including memory loss. According to wiki, there are half a million homeless people in the US. Surely you can throw in a few more thousands (but again, not in the same place or time). Make sure they have facial hair and dirty clothes.

  • 4
    $\begingroup$ Don't forget changelings! Fairies have been doing this for a long time. $\endgroup$
    – Willk
    Aug 28, 2019 at 18:29

Check this out:

Why did the population of Bhutan drop by 70% between 2007 and 2008?

(...) between 2007 and 2008, the population of Bhutan dropped from 2,327,849 to 682,321 people.

And the chosen answer:

The population of Bhutan had been estimated based on the reported figure of about 1 million in the 1970s when the country had joined the United Nations and precise statistics were lacking. Thus, using the annual increase rate of 2–3%, the most population estimates were around 2 million in the year 2000. A national census was carried out in 2005 and it turned out that the population was 672,425. Consequently, United Nations Population Division reduced its estimation of the country's population in the 2006 revision for the whole period from 1950 to 2050.

There was no such drastic decline in population, just inaccurate data.

So apparently you have wiggle room to shove a million people in a random third world country. Later you can collect those people back for analysis and blame any wrongful counts from the government on poor data processing.

  • 5
    $\begingroup$ It is just about some bad stats. If an actual million of people disappeared/showed from nowhere even in some God-forgotten Ruritania, that would cause an uproar. $\endgroup$
    – Vashu
    Aug 29, 2019 at 6:32
  • 1
    $\begingroup$ @Vashu Stalin makes your argument invalid. $\endgroup$ Aug 29, 2019 at 10:22
  • 1
    $\begingroup$ Not sure how applicable this is. The official population count being off by a million doesn't really affect people's day-to-day lives, but if a million people suddenly show up or disappear, doubling/halving a county's population, it will be noticed. The fact that society doesn't blink when some bureaucrat's figures change suddenly doesn't mean that nothing would happen if the reality actually changed suddenly. Stalin had the resources of the entire government to hide disappearances, but in this situation, the aliens have to hide from the government. $\endgroup$ Aug 29, 2019 at 13:58
  • $\begingroup$ Adding thousands of people without proper memories will be noticed by the population of the country and can become a reasearch topic. Just because you didn't know the population of Bhutan exactly, doesn't mean that the local population won't notice the sudden overcrowding. $\endgroup$
    – Chieron
    Aug 29, 2019 at 15:25
  • $\begingroup$ @Renan Stalin shot 0.6-0.8 million, and believe me, people in USSR and in the world noticed that. $\endgroup$
    – Vashu
    Aug 30, 2019 at 5:02

This is such a "trope" in science fiction. From an episode of X-Files where these vampires were all living in the same trailer park. To the movie Blazing Saddles where everybody in Rock Ridge was a member of the Johnson family.

Once you get even a few adults in, the rest goes pretty smoothly. Say you get five or six in some local town government bureaucracy. It all depends on the first few people getting in and getting a foothold in local city government. They can fake up required records such as birth certificates.

The first few may need to be gotten in through some kind of identity theft. Supposing you are nice aliens. Maybe you must follow around a lot of people and wait for somebody in a usable job in City Hall to die of natural causes. Then you sneak up on the corpse and BLIP! You have ID. If you are less nice maybe you have to hurry it along. If you are really horribly not nice, maybe you also have a snack.

Once the local community gets big enough, you can even have things such as the mayor, the police chief, and the town doctor being your pals.

Example: New subdivision goes up. It's operated by a "front" corporation, incorporated in the town by the original five people in City Hall. Every house is sold to your pals. This gives several thousand people a steady and stable home base from which to operate. They can send people out to nearly everywhere. Now that they have a home to come back to, and a home address to put on forms and things, they can do nearly anything. Go to university, run for public office, open businesses. The fact that their paperwork starts and stops with one particular City Hall is easy to obscure and hard to untangle.

Example: New trailer park gets built at the edge of town. All the permanent residents are your pals. Now they have an easy to defend origin story. They can then hop to other communities in other cities and openly integrate into society. Jim-Bob in the trailer park gets a job and becomes James, the accountant, with a semi-detached bungalow in Terracotta, Texas.

Example: Whatever the appropriate buzzwords are for making an immigrant look attractive, one of your pals fills in the form with that. And when he shows up, a local, also one of your pals, is there to sponsor him and support him. And he takes his place as a proper and legal immigrant, officially from Lower Slobovia,but actually one of your pals. The pals in City Hall make sure all the paperwork is properly approved, stamped, signed, and filed.

Once there is even a smallish community, they can start having a lot of babies. Then to avoid drawing attention as "the most baby-having town in America" they can start moving to other communities and set up the whole process again. And each new baby is duly and correctly registered as a new citizen of the country.

Edit to respond to the comment from Alexander:

Getting by this depends on how nice the aliens are. But basically, it requires burning down one records building, and then filing for a bunch of delayed birth certificates to make up for it. With a little jim-jam on dates, you could easily get several hundred people in this way. The "how nice are your aliens?" question revolves around how much damage, and how many people are injured or killed, in the fire? Possibly, if they are really nasty aliens, every person killed becomes one more stolen identity. Imagine that the fire takes place on "take your kid to work day" so that single-moms with one kid become family package deals.

The real trick is to not pull this on anybody who has fingerprints on file. If there are prints on file it could be awkward if the replacement is ever picked up by the FBI for some reason.

  • $\begingroup$ The local government may be able to fake birth records, but if the country has a concept of a national identification number (like SSN in US), a flurry or requests for a new number for adults would definitely raise some red flags. $\endgroup$
    – Alexander
    Aug 28, 2019 at 20:06

Where do you want them? If it's just a case of having your humans introduced to "normal" society, start in central Australia - construct an elaborate underground/hidden city (or even a network of cities) with food and water sources such that it can't be detected from the air, and populate it with as many humans as you can.

Then send a copy of someone you already abducted in the Australian desert (or abduct someone in the vicinity to prepare), give them memories of getting lost, and of being rescued by the "lost tribe". Finally, have them stumble back into civilisation - or at least onto a road to civilisation when there are likely to be several people driving past. The government will notice, but - assuming you have been careful - they won't be suspicious.

The only risk you then run is pesky human scientists trying to prevent your subjects from integrating into global society, so that they can perform their own science on these "natives" and their culture.


Per mille of the current country (region) population. So for the states it would be around 270000 people.
We're talking about just before government noticing. Because government monitor not only amount of people coming into their countries but also the amount of people from "sources". So what would be suspicious is all those people poping out but without a trace "from where".
I also assume your race is smart enough to not do mass dumps of specimens in remote locations but distribute them evenly according to local population and information nodes (I assume 5 thousand people a year without memories in Wyoming would get noticed in central database while same amount in New York would be statistic).
Also using disasters to cover their tracks. A few dozens of people showing up after a California wildfire would be probably noticed but overlooked, hundred of people with dementia and without documents after a hurricane in Florida would be explained with some undocumented Care home for seniors.
You need to have in mind that your specimens NEED to have some initial interaction with government for creation of documents (undocumented illegal flying under the radar could be possible in some countries but their research would be needed only to see how illegal aliens fit in regular societies).


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