A humanoid woman from another planet accidentally stumbles through a portal to 2024 Earth. I want her to be able to learn English in just a few days from overhearing my characters speak. Is there any way a humanoid species could evolve to pick up a language this quickly?

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    $\begingroup$ As a magical space alien, she will have powers sufficient to drive the plot of your story, if that is what you need. Humanoid aliens that somehow pass for terrestrial women and portals that connect different worlds together already require significant suspension of disbelief. If she can be engineered rather than evolved, that's a different story, of course, because that can certainly be handwaved away with sufficient alien compute power. $\endgroup$ Apr 19 at 13:56
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    $\begingroup$ Perhaps if they could read minds so that they could connect concepts with the sounds being heard? $\endgroup$
    – David R
    Apr 19 at 14:38
  • $\begingroup$ Is there anything stopping her from reading books or going on a computer at a public library? $\endgroup$
    – M S
    Apr 19 at 16:32
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    $\begingroup$ @MS How does a person "read books" if one has no language skills to begin with. Children learn to say "cat" long, long before they are introduced to 3 squiggles that represent the word & concept of "cat" in written form... Those squiggles don't come with a "pronunciation guide" (except the parent/teacher who diligently demonstrates how to interpret them.) $\endgroup$
    – Fe2O3
    Apr 20 at 0:18
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    $\begingroup$ @Fe2O3: There is the well-known exception of Tarzan, who learned the squiggles from illustrated children's books and only much later was taught that m-a-n was pronounced homme and a-p-e was pronounced singe. (And even later he learned that D'Arnaud had taught him spoken French and that the actual English pronunciations of the squiggles were different.) (And in the spirit of the question, one of the distinguishing attributes of Tarzan is that he can learn foreign languages extremely fast.) $\endgroup$
    – AlexP
    Apr 20 at 8:37

6 Answers 6


Depends on the expected level of competence.

  • Learn a few words and phrases, me Tarzan you Jane, me hungry need meat, yes, it is possible and actually expected from a human of ordinary intelligence.

  • Learn words such as humanoid or portal, or learn to use indirect speech and the sequence of tenses, not really.

The problem is that in real life, learning a language by total immersion is limited to what one can hear; in Chomskian terms, it is the problem of the poverty of the stimulus.

On the other hand, this real-life limitation has never ever been a problem in fiction, where is is quite common for various characters to learn to speak foreign languages fluently in a suprisingly short time.

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    $\begingroup$ Me humanoid alien. Me have difficulty with subject pronouns and definite article but otherwise quite the fluent. $\endgroup$
    – James K
    Apr 20 at 7:12
  • $\begingroup$ @AlexP what if I had the alien woman learn English slowly over time, albeit much faster than humans can irl, but still showing a progression ie in chapter 2 she might say "me hungry" but by chapter 10 she'll be sounding more like an elementary schooler. $\endgroup$
    – www
    Apr 20 at 7:51
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    $\begingroup$ @www: I don't know about extraterrestrials, but human adults never speak like elementary schoolers. In reality what happens is that human adults speak foreign languages mostly correctly, with or without a horrible accent depending on how good their ears are at picking up the subtleties of foreign pronunciation, but almost always with bizarre (from the point of view of the native speakers) gaps in grammar and most often in vocabulary. You may want to have her speak good idiomatic English and then ask "what's a witch?" or "how do you call that tool you drive nails with?" $\endgroup$
    – AlexP
    Apr 20 at 8:22
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    $\begingroup$ You might be able to get around this "poverty of stimulus" by having the alien go to a computer and open up like 10 different YouTube channels and watch them all concurrently (if they are able). At a certain point in learning a language, one gets a feel for the syntax, but doesn't know enough words to say what they want to say. It helps a lot if the alien has a perfect ability to remember everything they experience. With that ability, they could potentially learn hundreds of vocabulary words a day. $\endgroup$
    – user4574
    Apr 21 at 23:50
  • $\begingroup$ @user4574 (Devil's Advocate:) With no foundation to use as a filter, the humanoid wouldn't be unable to distinguish which of YouTube's 'n'00 languages she is paying attention to on each her "channels". Even discounting any single language's allusion, slang and simple jargon, exposure to a plethora of spoken languages would make this task exponentially more difficult. Consider the many meanings of the simple English word "pipe". Later, "I like your pipes. Wanna dance?" She replies, why not in Russian, "Dah!," but stays seated. We'd ALL like to dance, but some of us haven't the talent. :-) $\endgroup$
    – Fe2O3
    Apr 22 at 2:17

There is a minimum quantity of language content necessary to learn a language to any fluency level. It's also quantifiable to some extent how much language a person could learn in n days through typical interactions. A space alien might be able to cram more by not sleeping for those days, and seeking constant interaction in ways that do not draw attention, but this probably only bumps up the quantity by x3 or x5 or whatever at most (recovers 8-10 sleeping hours, seeks levels of interaction most people would find uncomfortable), even in a major cosmopolitan city (where some public space is always open for business and occupied).

Assuming that the alien learns languages at the fastest possible rate (like a LLM model on souped up hardware), a few days is probably insufficient for true fluency. They are currently trained on gigantic corpora of text, and while no doubt newer techniques will eventually demonstrate that the size of the training material can be reduced, certainly it must also be true that most or all of the words in a 40,000 word vocabulary must be present multiple times. This will be easy for a few thousand words in that list (how many times did you hear the word "the" yesterday?), but for others the alien might be lucky to hear them once within a week, and for yet others lucky to hear them once even in a year of 24 hour interaction.

It's possibly true that the quantity of input can be boosted if we suppose the alien can follow multiple overlapping third party conversations in the places where those tend to occur. We've all been in the noisy restaurant. The increase is going to be more modest than you might think, however. There must be a limit to its range of hearing, there is a reduction in the "bitrate" of conversations held in such places (think how many times you have to repeat yourself so the other person can hear you), and most of all these conversations will have zero context. The alien can't even try to use the new words correctly (to test whether it understands them) to any great degree, because while it might hear twenty overlapping conversations at any given time, it can only really participate in one or two. And that's assuming that conversations heard at a distance are useful, it's unclear how much nuance can be lost when you can't see the other person's face or body posture.

I take "just a few days" to mean fewer than a week (would anyone call a 2 weeks a "few days"?), and I don't believe there are any plausible (or even contrived) circumstances where the alien could learn English fluently in that time period. However, even actual people can sometimes learn to be communicative with a few days of immersion, speaking and hearing/understanding a few hundred words and the simplest parts of grammar.

My half-assed speculation is that fluency equivalent to the typical native speaker couldn't possibly happen in fewer than 2 months, and that only with superhuman abilities and fluency being prioritized above all other possible goals.

PS If TV Tropes doesn't call this the Stargate SG-1 Problem, someone's falling down on the job over there.

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    $\begingroup$ what is the absolute highest level of fluency she could achieve within a week? Could she express at least basic concepts? $\endgroup$
    – www
    Apr 20 at 7:52
  • $\begingroup$ She could learn courtesy words/terms, know when to say thanks and "excuse me". Greetings. This is all stuff you could learn in a few days yourself if you were a devoted student. But with superhuman abilities, she might be able to hold simple conversations, and get the grammar right more often than you or I could even in a month. She'd understand the context in ways you or I might struggle with. This one's about local politics, this other conversation is about entertainment fiction, and the one over here is about employment or temporary traffic navigation hiccups. She could be functional. $\endgroup$
    – John O
    Apr 22 at 14:08

Here's a benchmark: I've learned to speak a language with the fluency of an 8-year-old in 24 days of total immersion plus 1-2 hours a day of grammar lessons. This was even a language from a family I had no experience with (Nepali). And I'm not any kind of genius. The grammar lessons were pretty important, though; without them, I expect it would have taken me 2 to 3 months to reach the same level of proficiency. And, I didn't learn to read/write at all.

So, here's things that would speed up your alien's learning:

  • supergenius intelligence and/or an eidetic memory
  • experience learning other human languages
  • structured lessons in grammar/vocablary
  • telepathy

The last is your best bet if you want the "fluent in 5 days" thing to work. If the alien is telepathic, and can interactively use their telepathy to improve their language abilities while conversing, they could reach fluency at superhuman speeds.

Otherwise ... I don't see that it can work, simply because the alien will be facing a much greater language barrier than I did. Nepali is at least a human language, and I'm a human, and I have experience learning other human languages. There's no reason to believe that the alien would even have the same concept of grammar as a human would. They might spend 3 days figuring out that our speech was communication at all.


Previous portal travelers transmitted a related language which the protagonist knows.

The people on the far side of the portal are humans descended from other portal travelers in the other direction. Make Earthling technology much more advanced than Portalworld technology for most of history, so that occasional groups of Earthling travelers end up in the history of empires and language groups, while Portalworld travelers to Earth have all ended up in folklore or forgotten.

Your traveler is either a native speaker of a language with a fairly recent point of departure (perhaps an English warship was sucked into a portal in 1630 and shipwrecked on the alien coast, where they founded an empire) or a linguist specializing in a weird historical language which appeared out of nowhere and had a brief but impactful period of use in a small geographical area.

In any case, she speaks a very similar language to wherever she ends up. With near-identical syntax and lots of compatible vocabulary, she is therefore able to put together the rest by immersion in a few days.


Probably the top end of what is possible is shown by Daniel Tammett, who famously learned to speak Icelandic in a week from zero to being interviewed live on Icelandic TV. He is an extremely rare, high functioning autistic savant. I believe he had no prior knowledge of related languages, though if you have a mind like that you may have soaked up something and then forgotten you had it. But he did have full access to teachers and teaching materials.

If she is a conventional organic humanoid, she won't learn fast enough, but her mobile phone might. It could probably not do this from ambient conversations because most people are not using enough words, with enough cues to what they are talking about. But it might be able to listen to hundreds of conversations in parallel.

Another, rather different story was that of the explorer James Holman. He was blind, and made journeys into regions where he had no knowledge of the languages at all. For example, there are accounts of him being landed on unexplored parts of the African coast, meeting the indigenous people who normally hid from landing parties, and being gently lead off into the forest by them, only to reappear months later. Perhaps part of his magic was to be so helpless that he presented no threat. He did not learn languages in a week, but he survived being isolated in a similar way many times.

  • $\begingroup$ Tammett's case is fascinating, but the fact that he had access to direct translations between English and Icelandic made that possible. If you'd dropped him into a town in Iceland with no English-speaking locals the task would be significantly harder. $\endgroup$
    – Corey
    Apr 20 at 9:45
  • $\begingroup$ "No prior knowledge of related languages": Hmmm, Daniel Tammet looks like the name of somebody whose L1 language is English. Both English and Icelandic are Germanic languages. (And neither of them went through the High German Consonant Shift, so that words remained quite similar.) Let's check your unprepared understanding of Icelandic: "Þetta er meistari hringurinn, eini hringurinn til að stjórna þeim öllum." (Stjórna means "to rule", the English cognate is "to steer". In Icelandic spelling, the letters <ð> and <þ> correspond to <th> in English spelling.) $\endgroup$
    – AlexP
    Apr 20 at 17:55
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    $\begingroup$ @Fe2O3: A most excellent video, exemplifying a (carefully chosen) short discourse in several Germanic languages. (And it even includes the rather divergent High German.) $\endgroup$
    – AlexP
    Apr 20 at 21:32
  • $\begingroup$ @AlexP Thank you for that!! Couldn't stop until the very end when "judgement" was pronounced! :-) Fascinating! Vielen Dank!! $\endgroup$
    – Fe2O3
    Apr 20 at 21:57

Perhaps recent developments have fortuitously provided a relevant example.

Asked Google: "how long does it take to train an open LLM model"


Training LLMs requires significant computational resources, making it expensive and resource intensive. Setting up the required computing power for training can cost millions of dollars. Training Time: It can take months to train a large language model. --Artiba.org

And, you could likely heat a small town through the winter with the waste heat produced.

I, for one, wouldn't want to be standing near the alien woman while she's learning a language in a few days. She'd be a "hottie" alright, but not for the slang meaning of that term.

In addition, like a virginal LLM, the character would have no way to pre-select and filter out words/terms that would not serve her in the future. Wasted time an energy learning the words and concepts of theoretical physics if she's only on Earth "to have her hair & nails done".

"Human level intelligence"
How long does it take the average student to become proficient applying learned skills to write computer source code appropriate for a wide range of demands?
Some very experienced and proficient coders claim that, years into their career, they are still discovering and learning aspects of a language they've used for a long time that were "new to them!"


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