I've used this expression countless times before and never realised it had its roots in the Hebrew language. I discovered that while reading, The Origin of the Bible. The expression is a Hebrew one that first appeared in this form in the Geneva Bible (1560). In Job 19:20, it reads:
My bone cleaveth to my skin and to my flesh, and I am escaped with the skin of my teeth.
This was a change from an earlier translation by Miles Coverdale (1535) which reads:
My bone hangeth to my skin, and the flesh is away, only there is left me the skin about my teeth.
Though the Geneva Bible is more succinct in its expression, when I saw Coverdale's translation, I suddenly understood what the Hebrew expression was getting at. Obviously we have no skin on our teeth, but Job is actually referring to his gums, the "skin" around his teeth. At this point in Job's lament, he was saying that he had so little flesh left that the only visible flesh on him were his gums.
That expression has evolved in meaning and has come to mean narrowly escaping a situation by the thinnest margin imaginable. For what can be thinner than the non-existent skin on our teeth?
Writers have been using the expression with this meaning for the longest time. Mark Twain remarked in his book Roughing It, "I made up my mind that if this man was not a liar he only missed it by the skin of his teeth." And Thorton Wilder wrote a Pulitzer-Prize winning play entitled, you guessed it, The Skin of Our Teeth.
In today's English Bibles, the sense of having narrowly escape is now in the verse. The ESV version of Job 19:20 reads:
My bones stick to my skin and to my flesh,
and I have escaped by the skin of my teeth.
The footnotes in the ESV Study Bible do note that modern readers think of the phrase as an idiomatic expression for just barely accomplishing or avoiding something. That meaning certainly fits the verse but readers get a deeper dimension when they realise the original meaning.
How interesting that the Hebrew language has contributed such a quaint expression to the English language.