In your opinion what were the three most important developments in communication history?

 Without a doubt the most important development in history is human speech.  Prior to this communication was just grunts and actions, similar to a bad game of charades.  It allowed for a message to be received and interpreted with greater accuracy.  Speech has never been replaced.  No substitute for one on one communication exists.  It allows for the greatest interaction and the ability for 2 way communication.

The second most important development is the written word. The development of writing allowed for the exact message to be sent from one person to another.  Prior to this development, sending a message was like playing the childhood game of telephone.  The message would be sent word of mouth from one person to another.  The message received would undoubtedly be altered from the message sent.  Written word has also stood the test of time.  People still write on paper and have advanced that all the way up to writing on computers.

Arguably the third most important development in communication is the pictogram.  Although pictures were just a precursor to the written word, it broke off later and become something of its own.  Art communicates a message that holds deep emotion within.  This type of art makes people solve a puzzle to find the message.  This not only increases intelligence, but aids sociology, and an appreciation for higher understanding.