I am currently reading Digital Biology by Peter J Bentley.

Here's a flavour of it..  This is how he justifies the application of evolution to areas outside its traditional biological role;

"Because the process of reproduction, selection and variation are clearly evident in language, we can confidently conclude that our languages do evolve. Unlike natural evolution, which operates in the physical universe of atoms, molecules and chemicals, and physical laws, language evolution operates in a different medium. Our languages evolve in a conceptual universe made up of brains, books, speech and writing – two entirely different universes and yet the same process of evolution."

(If you want to referece the quote, it's page 62 - Bentley (2001) Digital Biology Simon & Schuster, New York)