Let's say that I have got colonists going to a far island, or to another planet far away. Let's say they have no means at all of communicating with the place they come from.

How long would it take for them to develop a different culture, language and et cetera, and forget their origin (or at least crumble it down to a legend or myth).


Two scenarios.

One: Medieval colonists with ships to isolated island.

Two: STL spaceship to Alpha Centauri, travel takes 8 years at half lightspeed, no means of communication to earth, modern tech with the developments required for such voyages.

  • $\begingroup$ This can't really be answered without more information about the technological level and numbers of the colonists. Can you try and specify that in more detail? $\endgroup$
    – Tim B
    Feb 23, 2015 at 16:29
  • 5
    $\begingroup$ I forget about my former civilization on the first day whenever I go camping. $\endgroup$ Feb 23, 2015 at 16:36

5 Answers 5


I was going to put this in a comment, but it got too long.

In short, there is no simple answer to this, as it is dependent on a wide range of factors. I will discuss several below...

Tech Level: Specifically, in the ability to create and persist records. If we are dealing with a primitive culture with no written language, then knowledge of their origins would be persisted only through verbal tradition, and would potentially start to drift from accuracy within a few generations. If you are dealing with an advanced culture with digital record keeping and the good sense to make back ups...then millennia down the road, the historical records could still be perfectly viable and flawlessly accurate.

Culture: This largely focuses down to a continuum with "Monastic-level interest in preserving accurate records" to "Totalitarian obfuscation of records" with "Meh" somewhere in between. As a great example of this, compare ancient Mongolian culture with ancient Chinese culture. The Mongols weren't too interested in keeping records and a vast swath of what we know about them is drawn from the records about them written by other cultures. Their histories were primarily verbal, and much of it was lost when their empire collapsed. On the other hand, we have tons and tons of precision details on ancient Chinese culture because they documented and recorded everything. In fact, that's why the Longyou caves in China are such a baffling mystery, because they are one of the few major projects of ancient China for which there are no records. And in a most extreme case, it is possible for a segment of leadership to arise over the settlement that will actively quash teachings of the past (to set themselves up as a god, or brainwash people to their line of thinking, etc)

Catastrophe/invasion: A sufficient catastrophic event can throw the line off in horrible ways. Ridiculous amounts of information was utterly lost when the Library of Alexandria was destroyed. We lost the knowledge of one of the most important civilizations in history (the Etruscans) when Rome rolled in and didn't bother translating anything from the Etruscan language...to the point that even though we have tons of writings from them, no one knows how to read it. Furthermore, a catastrophe can temporarily swing the 'knowledge-preserving' culture of a group towards the 'survival first' side of things, and cause the loss of much knowledge when people start burning the record books just to stay warm. Or, in the case of an interplanetary colonization effort, if the ship fails, and all the nice tech they brought with them is destroyed...they may not have the capabilities to recover. Especially if it is a seed ship, rather than a traditional colonization ship.

So, in short, there is no simple answer. If everything goes 'right' then they may never forget their origins (see: Ancient China). If everything goes 'wrong', they could have completely lost their origins within a few generations.

So, for the purposes of a story you are building a world for...the answer can be 'however long you want,' as long as you mix in the right tech/cultural/event factors to justify it.

  • 4
    $\begingroup$ As a fictional example how you can completely remove all knowledge of history form a society within one human lifetime when you really try, I recommend George Orwell's 1984. $\endgroup$
    – Philipp
    Feb 23, 2015 at 17:36

Like many such answers "it depends". Were they effectively crash landed? Where they running from something? Like colonists running from religious persecution?

For everyone to mostly forget you need to have at least the first generation not born there to die off. After that it will depend on how much the past is revered, and how obvious it is they hadn't always been there. If the traveling generation wanted to forget the past and where they came from, then by suppressing information about it and discouraging questions like that, then just a few generations after they die off, the past will start to become legend and folk-tale.

If they are using technology that they have no way to reproduce (and it doesn't fix itself) then this would slow down the legend conversion. Since this would be a constant reminder that they can't do something they used to. Though even that eventually would become part of a legend (or it's magic!).

Now if it is just a normal group that would mostly care where they came from, then you will need to expand the minimum time to hundreds of years, unless in the middle a catastrophe happens that would interfere with normal passing of information from one group to the next.

Having a computer network would also help keep the knowledge around, unless of course it is purged (on purpose or accident). So if you have a group that is left there with minimal survival gear and have to make their way with, the past will be forgotten faster, if there is a good tech background with computers and other modern conveniences (that they can replicate) then it could be hundreds or thousands of years .


Medieval Scenario: In this case we can use our own experience. We still have a rough idea of how things were during the middle ages. Knowledge was mainly passed on thanks to oral tradition, but monks also kept records of things in books. So as long as a writing record is kept, the story could be remembered for a long time. However the problem with a society where information is rare is that it is subject to accident. A fire in the wrong place could destroy all the info on colonisation easily.

That means that the memory will decade over time. Giving a precise time is impossible, but a few centuries may be a good guess. For example there are many myth from antiquity that may have actually happened. In a smaller society, memories would fade faster.

SF scenario: Thanks to modern technology, the rhythm at which information decays has decreased a lot. Therefore as long as technology level stays the same, we can imagine that this information could be remembered for enormous periods of time. Though after some time some people may not believe it anymore (aka. conspiracy theorists).


Personally, I know the outline of my family history since the 1930s, plus individual events from 1900 and the late 19th century. I know the name of one 16th century ancestor, but not the steps in between -- I have to take it on trust from the older folk who did the research. This is a combination of oral history and documents/diaries. The documents put the oral history into perspective and prove it beyond reasonable doubt.

Surely an event like a landing and the foundation of a village/town/civilization would be re-told for a long time. The intervening details might become murky, but things like "great-great-great-grandpa was the assistant navigator" would be remembered, especially if his duty on the voyage means the family got a choice plot of land afterwards.


Two very important questions:

  • Does the culture have a written history, or an oral one?
  • When telling history, does the culture focus on making the retelling as factually accurate as possible (as modern western culture does) or as thematically accurate as possible (as some other cultures have)?

The second question is more important than the first.

If the important thing about history is considered to be the story, the theme, and the lessons to be learned, then the actual facts of the history would begin to be forgotten after four or five generations for an oral culture, or more slowly starting a few generations later for a written culture.

Contrarily, if the emphasis is on factual recollection, then even a culture with an oral history would likely remember those facts for centuries, a written culture for millennia.


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