Spanish and Portuguese, for example, are very similar languages that evolved from Vulgar Latin over the past two thousand years or so. We know a great deal about their histories, the occupation of the Iberian peninsula by the Roman Empire etc. But I suppose things are not always so easy for historical linguists.

When linguists find documents that attest the existence of two obviously related languages for which is impossible to establish reliable dates, there are, at least, two possibilities of relationship between them:

  1. both languages descended from the same proto-language
  2. one is a more modern version of the other.

Would it be possible to establish how they are related based on linguistic data alone?

  • By the way, Paula, I don't know if you saw it, but your question might be fit for our Challenge Week about Historical Linguistics. If you wish to participate, just read the instructions you see there! :) (If you have concerns/questions, feel free to post an answer in that same question.)
    – Alenanno
    Feb 14, 2012 at 23:50
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    If "one is a more modern version of the other" it means that they descended from the same proto-language, right? For example, French and Old French both descended from Latin. Normally, living languages don't have daughter languages (because languages always evolve), except for "frozen" language like Classical Arabic or Latin
    – Louis Rhys
    Feb 15, 2012 at 2:15
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    Kamil S. and Louis Rhys both raise a good point here. You'll sometime hear non-linguists say something like "Welsh is a really ancient language" or "Dutch is older than Afrikaans." But you should keep in mind that that's a sloppy and imprecise way of looking at the situation. Really, modern Welsh, Dutch and Afrikaans are all equally old -- or, better, equally young, since they're languages spoken right now and that's about as young as it gets! Feb 27, 2012 at 15:12

1 Answer 1


Actually, there is at least one more possibility: [3] the similarities might result from intensive influence of one on the other.

Now, to the answer:

  1. Genetic (or genealogical, as I prefer to call it) affinity is quite difficult to prove beyond doubt. Perhaps the best way is to find a large number of regular sound correspondences in the most basic parts of the vocabulary, such as affixes, pronouns, low numerals, etc. No one can really tell what large exactly means in this context (see point 3), but if you can do that, the two languages will be considered related. Most Indo-European languages belong here.

  2. An older version is only possible if at least one of the two languages is already dead. So, for at least one of them we only have a limited number of texts. If definite statements are to be made on this basis, these texts must either be rather long, or very obviously related, i.e. the great majority of affixes and basic words used in them must demonstrably and regularly correspond to the respective forms in the other language. For example, Latin has a large base of texts and they can be shown to regularly correspond to Italian.

  3. Intensive influence is what is suspected when large from point 1 is not large enough for everyone, i.e. there remains a considerable number of affixes, etc, which do not correspond between the two languages. The Altaic "family" (Turkic + Mongolic + Manchu-Tungus + Korean + Japanese) is a good example of that. Linguists have argued for around a century now whether they are a family in the genealogical sense, or just have influenced one another very deeply in prehistoric times.

So, the main problem is the quantitative proportion. You might think that it would be enough to count the number of correspondences between the cases we are already certain about, and see if the appropriate numbers are higher or lower in the unclear cases. Unfortunately, no. Linguistics does not live in a void and in practice linguists always take historic, geographical, archeological, etc, evidence into account. Sometimes a relatively low number of correspondences is enough to pronounce affinity because the other pieces of the puzzle are very clear, but at other times the other pieces are few and so harder evidence is required on the linguistic side.

To sum up, linguistics alone can determine how two languages are related but not in every case is the conclusion certain. Sometimes, it is merely more likely than the alternative possibilities.

  • Exactly! The words chrism and Kiritimati share a common etymology which would be inscrutable without a vast array of historical knowledge ranging from ancient Hebrew ritual practices to the travels of an 18th century British sailor. Apr 14, 2012 at 2:00

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