I remembered reading an article that made the case that computer keyboards evolved from scientific calculators which had the arcmin and arcsec symbols but no use for quotation marks.

After thinking about this for a bit and reading Wikipedia (http://en.wikipedia.org/wiki/Quotation_mark#Non-language_rel...) I am starting to think that this is wrong. Keyboards obviously mirror the typewriter and not the calculator. Thanks for making me think about this!