عنوان مقاله [English]
Relative chronology in historical linguistics refers to temporal order of sound changes affected a language. Because a sound change is restricted to a particular period of time in the history of the language in which it takes place and this enables us to solve apparent problems with which we sometimes are confronted. This means that some sound changes may take place in the language at some earlier stage, whereas others may take place at some later stage in the language’s history. Often in the case of different changes from different times, evidence is left behind which provides us with the clues with which to determine their relative chronology, that is, the temporal order in which they took place. Therefore part of working out the phonological history of a language is determining the relative chronology of the sound changes which have affected the language.
In Iranian languages also there are some cases where the different temporal order of sound changes has an important role in the process of sound changes. In cases where we find morphophonemic variation in development of words, it may be affected by difference in temporal order of sound changes. In this paper After an introduction on relative chronology and its special use in historical linguistics, by examining the chronological order of sound change in development of some words in Iranian languages, it will be shown that how and why relative chronology can solve some problems with which we sometimes are confronted in working out the sound changes of a language.
In the history of Baxtiari we find the change of Middle Persian āmad- “to go” to āveδ- (then aweδ-) in Kuhrang variety and ovay- in Iza variety. In this case Baxtiari underwent two changes: A. ā → o / — m, and B. m → v / V —V. in Iza variety the change took place in the order A→B, but in Kuhrang variety first the B change has applied, and the use of B change has eliminated the phonetic environment for sound law A, since the B had taken place first, then there would have been no remaining m to condition the change A. Another example of affecting relative chronology is seen in Middle Persian *mista to mīsa and mēsa “urine” in some varieties of Boirahmadi, where among the two change A. Vst → V̅s, and B. i → e, the order B →A has resulted to mēsa, while mīsa is developed by only B, because A change has eliminated the condition for B change. The same thing has occurred for Middle Persian brūg “eyebrow” to Persian abrū/borū, where final postvocalic –g is deleted, while in Lori borg “eyebrow” by metathesis of r the word retained its g because it was not word-final. One more example is development of Old Iranian *wafra- to var “snow” in Tati and Semnani, where the f is deleted before r, but the metathesis of r with f in some Iranian languages such as Persian, Lori and Meymai have changed the condition for deletion of f, and we find this word as barf and warf in these varieties where the f has retained.
Most Central dialects have pür “son” and sür “red” developed from Old Iranian *puθra- and *suxra- respectively. The compensatory lengthening of u has resulted to *pūr and *sūr, then through general change of Old Iranian ū to Central dialects ü, the form pür and sür is developed. Here the compensatory lengthening of u, provide the necessary condition for fronting of ū to ü. The same change has occurred for development of næɁl “horseshoe” to nɑːl in Lori which deletion of Ɂ and compensatory lengthening of æ has resulted to development form næːl, then by general rising of æː to ɑː the form nɑːl is formed. Again compensatory lengthening has provide the necessary condition for rising of long vowel in this word. The words such as etmiːnɑːn “confidence” and iːmɑːn “faith” in Persian have been developed in the same way from its proto-form itmiɁna:n and iɁma:n.
All the examples show that determining the relative chronology of the sound changes has an important affect in process of words development, and considering it can solve some problems with which we sometimes are confronted. We see that applying a sound change can eliminate the condition for another sound change and prevent its occurrence. While some other changes may provide a condition for a secondary change that affected the word. Different chronological order of sound can also be a reason for developing different dialect of a languages, where a particular sound change order may distinguishes a variety from other dialect which underwent another order of sound changes.