This blog post I thought was helpful and informative in terms of answering - why are so many people sensitive to gluten? Why is sentitivity increasing?
Sarah posts several bits from medical journal articles and some of the most common scientific "guesses" as to why so many people have developed gluten in tolerances, such as genetic engineering of wheat to contain higher levels of gluten, and the result of several generations of people eating way more gluten than they used to.
I don't agree with Sarah that gluten is a poison for all people, although it certainly is to me. Gluten is a complex and difficult-to-break-down protein, like casein (one of the proteins in dairy products.) So it makes sense that a stressed-out system might react against digesting it. There is some evidence that the ability to digest gluten slows down with age and that more women than men are sensitive to gluten and are unable to digest it. I hadn't read about the thyroid connection mentioned in the blog post, but I guess that makes sense - I also have autoimmune thyroiditis, and apparently people with that condition are much more likely to have celiac disease.
The testing for celiac disease she mentions is indeed problematic, but if you'd like to get tested without going back on wheat, there is a DNA test for the celiac disease gene you can ask your doctor about. (I am not a doctor and this is not medical advice, usual disclaimers, blah blah blah.)
I thought those of you who were curious about gluten and gluten intolerance might enjoy reading her post. It's a pretty accurate conglomeration of everything I've read on the subject thus far, with the above caveats.