Should also mention that language also evolves. Culture, beliefs, ideas, etc, these are all memes that people pass on to each other. Ever wonder why suggestion is so powerful? Why people like Derren Brown can "hypnotize" and manipulate people so easily, with nothing more than words?

Ever wonder why so many people kill others over beliefs? If a group of people believe something, the only ways anyone can stop them from believing is to kill them. Or join their belief system, just like Mohammad did to start Islam. Hence all the religious wars.

Ever wonder why it's getting harder and harder to find anything unique or interesting to listen to, or watch or read? Most people are just hosts for memes, walking around spreading them like a virus. They don't have original thoughts, they just mimic and copy others.