In this specific case, we happen to have records of a group of languages called Epigraphic South Arabian. Comparative studies have determined that these languages are actually more closely related to Ethiosemitic languages than to Arabic and, consequently, they are classed together in the South Semitic branch (which, as I explained previously, does not include Arabic). I'm not sure when the first South Arabian inscriptions appear, but I think it may be as early as 900 BCE--so much for your hypothesis of "mutual intelligibility" 1500 years later!
In the absence of those, linguists fall back on fuzzier measures. Attempts to develop a rigourous science of "glottochronology" have foundered on the inability to demonstrate a constant rate of language change comparable to radioactive decay. (Applying rates of change developed from analysis of the continental Germanic languages, for instance, gives a time-depth for the divergence of Icelandic from Old Norse that is laughably small--something like 200 years instead of 1000.)
Nevertheless, historical linguists seem to have strong gut feelings about the minimal amount of time it takes for divergences to reach a certain point (at least in the absence of catastrophic change such as creolisation). Even if we couldn't compare Ge'ez (well attested since about the 5th cent.) to Classical Arabic (from at least the 7th) and demonstrate their considerable dissimilarity, it would still look extremely unlikely that one could get from a common language to the tremendous diversity exhibited respectively by modern Ethiosemitic, Modern South Arabian, and Modern Colloquial Arabic.
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momijizukamori
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Date: 2007-04-22 04:49 am (UTC)In the absence of those, linguists fall back on fuzzier measures. Attempts to develop a rigourous science of "glottochronology" have foundered on the inability to demonstrate a constant rate of language change comparable to radioactive decay. (Applying rates of change developed from analysis of the continental Germanic languages, for instance, gives a time-depth for the divergence of Icelandic from Old Norse that is laughably small--something like 200 years instead of 1000.)
Nevertheless, historical linguists seem to have strong gut feelings about the minimal amount of time it takes for divergences to reach a certain point (at least in the absence of catastrophic change such as creolisation). Even if we couldn't compare Ge'ez (well attested since about the 5th cent.) to Classical Arabic (from at least the 7th) and demonstrate their considerable dissimilarity, it would still look extremely unlikely that one could get from a common language to the tremendous diversity exhibited respectively by modern Ethiosemitic, Modern South Arabian, and Modern Colloquial Arabic.