In a cultural worldbuilding scenario, what would turn a whole multitude of languages to sound virtually nothing like their common ancestor?

Question

Allow me to clarify by starting with the opening paragraph of the Wikipedia article on "Proto-Indo-European language":

No direct evidence of PIE exists – scholars have reconstructed PIE from its present-day descendants using the comparative method.[4] For example, compare the pairs of words in Italian and English: piede and foot, padre and father, pesce and fish. Since there is a consistent correspondence of the initial consonants that emerges far too frequently to be coincidental, one can assume that these languages stem from a common parent language.[5] Detailed analysis suggests a system of sound laws to describe the phonetic and phonological changes from the hypothetical ancestral words to the modern ones. These laws have become so detailed and reliable as to support the Neogrammarian rule: the Indo-European sound laws apply without exception.

So in a different world, a language spoken by a particular population underwent a similar path but diverged into a language that sounded nothing like its ancestor. What sorts of circumstances could make that sort of evolution possible?

No alien involvement, magic or total extinction scenario, thank you.

Answer 1

No special circumstances necessary, this is what is happening with Earth languages, if the circumstances are right.

English is a good example - the Great Vowel Shift made the English vowels quite unlike other Germanic languages. Combined with the influx of French words, English does not only sound differently because of her phonetic inventory, but also because of the differences in the vocabulary.

In Romance languages, the equivalent outlier is French - it lost quite a lot of word-final consonant, got a lot of nasalisation and of course the very distinct «r».

Moreover, in order just to sound differently, you do not even need the languages to diverge, just consider non-rhotic English variety compared to rhotic and vowel-breaking varieties - that is quite different and you would not even guess it's almost the same language, if you happen not to speak it.

Other quite small changes that can change the perceived language (especially by non-speakers) are the emergence or disappearance of tones, creolization, changes in stress patterns (Eastern Slovak sounds quite different compared to the standard language, the former has penultimate stress, the latter word-initial), reduction in vowels (Brazilian Portuguese sounds quite different compared to European one) - and that's all even within one language.

TL;DR - Indoeuropean languages already diverged many iterations beyond the "sound virtually nothing like" threshold.

Answer 2

Their Main Language was Phased out by a Constructed Language

Constructed Languages are completely new languages that people just made up. Generally speaking, Constructed Languages fall into one of 3 categories:

Engineered languages: Invented to serve a specific purpose. These normally preserve a lot of the original language, but add a lot of new lexicon or grammar rules to make communicating things that were difficult to communicate before more possible. Programing languages are a good example of these.

Auxiliary languages: These are languages are invented to allow international communication. They often strip away any grammer or phonetic rules that are difficult for one group to grasp, but keep things the languages have in common.

Artistic languages: These are languages invented purely for artistic reasons. They often have little to no common phonetics with the original language, but often (but not always) use the same rules of grammar.

So to answer your question, what you need is for an Artistic language to overtake the main language. Artistic languages are usually the hardest to see adoption with, because there is no real reason for everyone to just start using Klingon or Tolkien's Elvish instead of English as you see with the other 2 types, but that does not make in impossible.

What you may have had was a particularly escentric ruler who learned an Artistic and liked it so much that he made it the official language of the nobility. Then just like English became mostly a French variation over time because the rulers where French, you nation would widely adopt a form of this constructed language.

From that point forward, many new languages evolved as they normally do.

Answer 3

Shift of religious power / decree from on high / mass education

Historically, religious organizations had a large amount of "learned men" who were members of the intellectual elite at the time. Often times, they had skill sets related to language completely unavailable to the common man. For example, until rather recently (on a historical scale), Christian sermons and church proceedings were done entirely in Latin (and some still are today). So, it's entirely possible that your religious cast has a language all to themselves--maybe the language the original sacred texts were written in or the language passed down via prophets from their god. Regardless, this great and sudden language shift could happen like this:

1. Common people speak "common" and the clergy speak "common" and their special church-language "nital". The average commoner can maybe say "amen" in "nital" but not much more--fortunately though, the sermons are held in common so they can understand them.
2. Over the years, the religion gains power. Maybe a new King or Emperor has close ties with the church. Therefore, in an effort to be closer to his god, he starts speaking and holding court exclusively in "nital".
3. The ruler's language habit is mirrored by the jealous nobility (obviously) and it becomes vogue to speak "nital"
4. Eventually, "nital" trickles down to the common man from their Noble overlords. If you want this to happen faster, maybe the Ruler starts a new education campaign to have a smarter populous, and decides that instead of teaching "common", the curriculum will teach "nital"

Answer 4

Your hypothetical language family could have formed creoles with other languages. Consider how modern English sounds nothing like Old English- that's because the Norman Conquest brought so much French into the vocabulary.

Answer 5

Morphological changes to either hearing or speaking parts

What we hear is influenced by the shapes of the ear and internal parts (the eardrum and a few tiny bones, plus the connection to the brain). Similarly, the sounds we make are influenced by the shapes of our mouths, tongues, vocal chords, etc.

If a genetic mutation results in substantial changes to the shapes of any of the body parts necessary for speaking or listening, that would set that population on a different trajectory of language evolution. Language will evolve over time anyway, but if the "hardware" changes underneath it, that evolution will be different than in a population whose hardware doesn't change.

There are all kinds of ways a genetic mutation can occur, and there are plenty of reasons it might spread, especially if the two populations live in different places.

Alternatively, societies can settle on some really horrifying ritual practices for cultural reasons. Imagine a society that becomes dominated by a religious or political faction whose practices include ritual mutilation. There are plenty of examples in real life: foot-binding, neck-rings, female circumcision¹; or less dramatically: piercings, tattoos, etc.

And deliberate mutilation is not the only way that a broad swath of the population can become physically deformed in unison. Certain occupations are known for having similar effects, like how cauliflower ear is endemic to boxers. Imagine if the Europeans who invaded America had discovered a land that was uniquely favorable for harvesting a specific natural resource, but the work involved is hard on the body in a way that leads to a specific set of chronic injuries.

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^{1. Humans have treated women really terribly. Be kind to the ones in your life.}

Answer 6

Isolation

Languages will diverge naturally if the populations have little or no contact with each other. Isolation occurs naturally when few people have little means or motive to travel long distances.

Consider the differences between romance languages, which are descended from Latin, such as Italian, Spanish, French, Portuguese, Romanian, and Catalan. They are languages of nations that are relatively close together and share many cognates, but are still distinct.

Slavic languages such as Polish, Russian, and Czech also share a common ancestor with Latin, meaning they also branched from the same source (Proto-Indo European) as the aforementioned romance languages.

Answer 7

One scenario could be colonization, where the colonizers ruthlessly force the colonized to abandon their language and adopt the language of the colonizers.

A second scenario could be the coming together, over a short period of time, of groups of people who speak different languages and they develop a hybrid language, something like Fanakalo in the mines of South Africa, which eventually becomes adopted and the only language used by all.

Answer 8

Time, a few hundred years is long enough to make communication between people speaking what might be considered the same language, modern versus old English for example, difficult. A couple of thousand years makes descendant languages unrecognisable as related unless you're an expert, Italian and Portuguese for example are both Latin plus fifteen hundred odd years. A few thousand years makes recognition and reconstruction of linguistic links a specialist science where the lineage of single words is the subject of multiple, conflicting, academic papers. Examples where this process is accelerated usually involve isolation of groups, either geographically or sociopolitically, who then develop strong regional dialects that eventually diverge to the point of mutual incomprehensibility.

Answer 9

Separation, whether it's geographic or cultural. The pronounciation of words will start to differ, and over the course of time they will drift apart.

You might consider the variety of different accents that exist in English. Many British accents will be almost unintelligible to Americans, or sometimes even other Britons. Then there are Indian accents, Jamaican ones, American regional ones... Yet aside from a few word differences, like "gas" vs "petrol", we generally have no problem understanding the written version of the language.

Answer 10

Disease that causes widespread deafness, particularly among adults, perhaps down to children of five or so.

Once it occurred, hearing children's only way to learn speech is from adults whose speech patterns would be modified by their inability to hear what they say, such adults as escaped the deafness, and each other. The lack of reinforcement of the original pronunciation would cause changes to happen much more rapidly than they do in ordinary usage.

A few epidemics of deafness could make the sounds unrecognizable.