The "Original Language" of The Hebrew Scriptures

I'm working on a journal article that examines the historic sound shifts in languages and the implications on ancient genealogies. More on that anon, but for now I'll examine the implications for the concept of the "original languages of scripture."

Leaving aside the New Testament, for which manuscript evidence is overwhelming, I focus here on the Old Testament, known as the Hebrew Scriptures. Our oldest copies of the entire OT date to the 10th century or so, meaning that they are many centuries removed from the time Hebrew was last used as a living language. The Dead Sea Scrolls evince a different script, but essentially the same vocabulary from a millennium earlier. Although some books (such as Job) do contain some words that are considered more archaic then what is in other books, nevertheless the 39 (officially 22) books of the OT--excepting the few Aramaic quotations, phrases, and names--are all in the language we now call Biblical Hebrew.

Is this possible? Can a series of books put into writing over a period of several thousand years all be in the same language?

The rationalistic answer is clearly No. All living languages change, and the Hebrew spoken by Ezra must have differed markedly  from the Hebrew spoken by Abraham. So different, in fact, that they would today be considered totally different languages, akin to the difference between the modern languages spoken by Abraham's descendants--the Jews and Arabs.

But what if the OT was written in a classical Hebrew that originated with Moses? No, even classical languages change. Latin evolved even after it ceased to be a spoken language, going through Late Latin and Medieval Latin stages, until we now have the Latin that forms the base for the International Scientific Vocabulary. Take Arabic, for instance. The Qur'an was put in writing some 1400 years ago, and is still the basis for written Arabic. Yet nowhere in the Qur'an will one find the common Arabic word for language: lughah (from the Latin lingua, 'tongue'). This, along with other classical Arabic words that form important primitive roots in that language (like jins, from genus), is a word imported from Latin some two millennia ago. The original (Koranic) word lisan is not used in written Arabic any more than is its English counterpart tongue, except as the name of a body part. So languages continue to change in little ways, even if their original religious form is kept intact.

This is the sort of change we should find as we read the Hebrew Scriptures from Genesis and Job down through Chronicles and Nehemiah. But it isn't there. The implication is that Biblical Hebrew is NOT the original language of much of the OT. Some earlier form of or ancestor to Hebrew was, and of it now no trace remains. All we have left is a translation.

UPDATE July 2012:
The Scriptures themselves give hints at how language usage evolved over the centuries. Here are a few:

- "Shibboleth" had lost some of its aspiration by Judges chapter 12.
- "Seer" was falling out of use by 1 Samuel chapter  9.
- Some Hebrew words are only found in Chronicles, where they had replaced older words in parallel passages of Samuel and Kings.