Not quite sure what you mean. I believe it was the invention of the protein hit (by cooking meat) along side walking upright to reduce our shadow area... (an invention to forage further afield?) ... in so doing both aspects provided cooler brains with high energy levels which went onto increase our whole nervous system, including full control of our rib cage which helped early man/animal develop speech, words and detailed communication.
The printing of words for the massed with the introduction of printing presses has got to be a big key in the evolution of standardized languages though right?
The internet information age being a similar evolution of our own invention.
It wasn't so much cooking meat that helped early man develop bigger brains, just cooking foods generally. It opened up a whole new world - before cooking man's diet was severely limited due to toxins and other undesirables. Cooking neutralises these allowing greater range of diet, the earliest evidence of control of fire (depending on your sources) is around 400,000 years ago by Homo Erectus. It wasn't widespread until around 125,000 years ago (see
http://en.wikipedia.org/wiki/Control_of_fire_by_early_humans)
From that source - "Richard Wrangham of Harvard University argues that cooking of plant foods may have triggered brain expansion by allowing complex carbohydrates in starchy foods to become more digestible and in effect allow humans to absorb more calories"
Regarding printing - there is no doubt it was a massive leap in the evolution of the written word. Beforehand, if you wanted a copy of a book you did just that - copy it, by hand (ha, think of the copyright issues...)
This was an incredibly laborious task and only a few people were able to do it, namely the church. This then means the church controls the written word and can say what they like without others questioning it. The printing press meant more accurate copies but that didn't necessarily happen straight away. Not many people could afford a press. Indeed most people couldn't read - the next major advancement in this respect was the King James Bible as it meant more people had access to the bible, this then had the knock on effect of more people learning to read.
However - writing was more widespread in other era's. Think egyptians and romans and ancient greeks for a start - it is thought that within these cultures the ability to read and write was much more prevalent than the medieval period, however they didn't have printing presses. The press was a very important invention of course but it isn't the complete picture, it in itself was not as revolutionary in terms of man's evolution into a more enlightened age. Knowledge was still 'owned' by the rich and powerful and most people still couldn't read, so for them it didn't really matter how many accurate copies of books there were around, they still had to rely on the few at the top of the ladder for information.
The advent of printing had little effect on unifying language though - there were just as many different languages and even within single languages it was still a case of 'make up spellings to suit'. Individual letters of a given language were more or less already standard, but things like spelling and grammar were very much a free for all for centuries to come.