What a joy to read, with an abundance of both wit and erudition! I’m particularly thankful for all the additional information not specifically called for in the original question. Obviously, “bibliophage” bubbles over with scholarly zeal and wishes to engage others.
I was puzzled, however, by the comment that “many standard English words have entered the language through mistakes (uncle from nuncle,…)” According to my old OED, uncle comes from the Latin avunculus, and the first English citation dates from circa 1290, while nuncle is but “a variant of uncle with transferred n,” and its first citation is dated circa 1589. The American Heritage Dictionary (3rd edition) similarly derives nuncle from the phrase “an uncle”. The big Random House Dictionary tells me that the Latin form avunculus was constructed of two parts: av- (shortened from avus, “mother’s father”) and -unculus, a suffix extracted from the diminutives of neuter stems. Nowhere do I find justification for regarding a “nuncle” or a “nunculus” as an ancestor of anyone’s uncle. How about that?
I’ll be a monkey’s … wossname. I would have sworn “an uncle” was from “a nuncle” by transference of the n, as “an apron” is from “a napron” and “a nick-name” is from “an eke name.” I was so sure of the fact, I guess I didn’t bother to look it up. Of course I was wrong. I’ll have that fixed. Thanks for bringing it up.
I forgot to mention that a link to the Staff Report is appreciated. You can provide one by simply pasting the URL into your post, making sure to leave a blank space on either side of it. Like so: http://www.straightdope.com/mailbag/mplurals.html
Sorry I didn’t include a link to the Staff Report. I’ve got the idea now.
You’re most welcome for the catch, and I hope to see lots more Reports from you!
The trick of using “mine”, “thine”, “hers”, “ours”, “yours”, and “theirs” only as the complement of the verb “to be” is relatively recent. “Mine” and “thine”, at any rate, were in the same position as “an”.
But the entire question is complicated, due to the fact that Old English, like most Indo-European languages, had both the genitive case of the personal pronoun and possessive adjectives, and, like the rest, tended to use the one for certain constructions and the other the rest of the time.