I'm not sure if this is a right forum, but I didn't find better from SE.
I wonder if it is researched how much development of writing systems affects to language compared to languages that are not written, or writing system otherwise developed very late in history?
Could you assume that languages which are solely orally been alive, have kept their vocabulary and structure / grammatics better than those with written? Or is it opposite instead?
I came to this question by reading a book "THE SILENT LANGUAGE" by Edward T. Hall who stated that:
It follows that writing is a symbolization of a symbolization
which suggests that certainly there must be a lot of influence to the language, when people started to write it. Similarly like recursion that adds something to the stack after each iteration.