Rate of linguistic change among geographically separated descendants of a common language

Question

I'm developing a story set on an exoplanet where a relatively small terraforming expedition is forced to settle on the planet due to some catastrophe 20,000 years before the story's events.

They settled the planet in 4 groups of approximately 3000-5000 on 4 separate large volcanic islands (think Iceland or larger). The habitable area of this planet consists essentially of these 4 large islands (which aren't that close to one another but essentially arranged in a linear fashion) and thousands of smaller islands in between.

Because of the relative lack of accessible mineral and metal resources on the planet, they were not able to maintain advanced electrical technology for more than a few decades after initial settlement.

Since then, the separate cultures have settled into a level of technology between the late Neolithic to early Modern period depending on the type of tech. For instance, metal weaponry and armor would be extremely rare and limited to certain groups, but windmills, sawmills, and even early steam power (for mechanical, not electrical purposes) are available.

Assume that the various cultures have some level of print technology, although the quality and ease of use may vary. So there has been some method of language transmission between generations.

The cultures were geographically separated for approximately 15,000 years until contact was re-established about 5,000 years before the story as the cultures began to spread to smaller islands.

Now that the background is established, here's my question. If the settlers of the planet all shared a common language, what level of mutual intelligibility would be expected after 15-20,000 years, if any?

On Earth, our oldest reconstructable languages are approximately 7000 years old and the level of language diversity is immense. But would that change if they were all diverging from a single, written language?

Maybe the closest analogue in Earth's history would be the Sinitic languages descended from Old Chinese, which has had a relatively standard written version for over 2000 years. Today, the modern Chinese languages form a spectrum of mutual intelligibilty, with more geographically separate languages being less intelligible in their spoken form.

Other things to consider might be the type of script that the common language used. For example, the Chinese script is logographic (each symbol generally represents only one entire word or idea), which means that often different Chinese languages can derive the same meaning from the symbol while using entire different words phonologically. However, if the common language used a very functional, pronunciation-informing script like Hangul (Korean script), would the phonological change be less rapid?

Answer 1

• One thousand years was sufficient for the Romance languages to evolve from Latin.

  In the 4th of the common era all the Romance languages (Portuguese, Spanish, Catalan, French, Provensal, Sardinian, Italian, Romanian) were one single language: Latin.

  In the 9th century of the common era, just 500 years later, when Charles the Bald of West Francia (which was to become France) and Louis the German made their armies take an oath of alliance, the Latin text had to be translated both into Germanic, which is quite natural, but also into very early Old French, which shows that by that time Latin was no longer understood by the common people.

  In the 13th century, less than a thousand years after the fall of the Western Roman Empire, Dante Alighieri wrote the Divine Comedy in what is essentially Modern Italian.

• One and half thousand years was sufficient for the Germanic languages to reach their modern forms.

  Two thousand years ago English and German were the same language, some sort of Proto-West Germanic, which, is believed, was still mutually intelligible with the ancestor of the modern Swedish and Danish languages.

• Six thousand years was sufficient for all the extant Indo-European languages to evolve from Proto-Indo-European.

  Five to maybe six thousand years ago, English, Spanish, Russian, Greek, Persian, and Hindi were all the same language: Proto-Indo-European. I can say without any doubt that after six thousand years of evolution their mutual intelligibility is zero. We can still detect that they are related, but it is not very obvious, and in fact their common descent wasn't even realized until the late 18th century.

• There is very very little hope to push historical linguistic reconstruction to a time depth of more than maybe ten thousand years, and even that is super optimistic.

  At the time depth posited in the question, 15 to 20 millennia, I would say that the different languages would appear to be completely unrelated. Only a handful of linguists (and crank amateurs) would insist that they could detect some wispy faint traces of relatedness, and would be ridiculed as fringe by the community.

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Now, that's orthodox historical linguistics. But the question throws an interesting problem, insisting that the various groups have always had printing during this time.

That's plainly not possible.

If they had printing, not fifteen, but only two thousand years ago, then by now they are a multi-planetary civilisation, zipping around their solar system, refining their incredibly advanced AI and rapidly progressing their incredibly advanced civilization. (For comparison, Gutenberg lived about 600 years ago. Look at what we did in 600 years.)

Once printing is invented, the rate of accumulation of new knowledge increases faster and faster and faster. You cannot have printing for thousands of years and somehow stagnate at pre-electric power levels of technology.

Answer 2

If there isn't enough contact between the groups to keep the languages at least mutually intelligible, there won't be enough for genetic viability even with 5000 people per group.

It's generally accepted that it takes a population of at least 20,000 to maintain genetic stability in a species like humans (mostly monogamous and single births the rule).

Therefore, it'll take at least a few individuals every few generations being exchanged between each group and each other group to ensure enough genetic mixing -- which will tend to automatically create enough linquistic mixing to keep the languages close even in the absence of printed books (which have historically done much to stabilize temporal linguistic changes).

This is not the say the languages won't drift apart -- look at the differences between Cockney, say, and Dorsetshire speech, separated by only a few days' travel even before good roads and under the same government for most of their history. Yet, if both are interested in communicating, two such (even in the late 19th century when their separation was greatest) could understand each other with some effort.

Answer 3

For that amount of time, I would expect virtually little to no commonality.

I'm going to use English, written English and Latin as my baseline for comparison.

Mostly because of it's significantly shortened time period.

I mean, even now, me - a native English Speaker who grew up in England - I can barely understand anyone from Yorkshire.

And only our accents have diverged in the last 200 years. For a humorous example - Clarksons Farm and Gerald.

Now, I'll grant that the preservation of Latin in the time period from the fall of the Roman Empire to when England really started to have a written language again wasn't great (which may fall afoul of your premise) and that during that time there were a few invasions (which injected other Languages into English) - however, the formal language was French (also a Latin based language) so I'm kinda giving it a pass here.

In 2000 years - the best I can do with Latin is recognize common root words and 'guess' their meaning.

You could probably look at the Greek Language as well - despite being written and spoken, modern Greek and ancient Greek - in 3,000 years - it is estimated that someone fluent in Modern Greek would only be able to understand 50% of ancient Greek.

The other thing with Divergence is that it isn't linear, often it accelerates and becomes more divergent with the passage of time than less divergent.

Answer 4

If you look at how quickly Latin dialects of the Western Roman Empire drifted apart into Romance languages of decreasing mutual intelligibility, while not only did writing exist, but an awful lot of contact too, I don't fancy their chances at understanding each other.

Even worse, look at how official and ceremonial Medieval Latin changed in pronunciation, despite a fairly strong central authority linking it all together.

Of course in both those cases a confounding factor is contact with other, non-Latin derived languages, and in the case of colloquial Romance languages the low level of literacy, but then again, it all happened over only a few hundred years.

In fact it's a valid question to ask how "same" the language of the original settlers was. Did they all speak the same dialects, with the same accents, did they use the same registers and so on?

(As a fun aside, we've now even developed an Antarctic accent apparently, in what seems like no time at all.)