With such a small number of people being able to read and write in them days, they would establish standards and spellings they agree on, and with the invention of printing presses production rates would have soared, and standards would have to exist. Imagine if each of the Gutenberg bibles was full of different spellings, in one a road might be "road" in the next it might be "wibbledyshazzlegooba". Nonsense. If they didn't stick to standards, the reader wouldn't know what the hell some words are.
As CodeCat has pointed out, all the European languages are related in ways and connected through common parent languages. Languages evolve, they didn't appear out of thin air... the only one that did that is Elvish, even then, Tolkien spent years and years working on it to the point that it could be considered a true language.
Edited by Calamity_Jones, 02 March 2007 - 01:45 AM.