William S. Burroughs
would revise the title of this node to "language is a virus from outer space
" (I'll go create that node too). I wouldn't go that far but I am comfortable ascribing all the properties of a virus to the notion of language. This is an idea further explored in Snow Crash
by Neal Stephenson
A virus is simply a pattern of information that replicates in order to propagate itself to other information storage systems. This is true for biological virii as well as computer viruses. A virus can mutate as it multiplies.
Have you noticed how slang terms come and go? I've often heard a word used for the first time by a friend, only to hear it in common circulation a few months later. Or you might learn a legitimate word and add it to your vocabulary. Eventually you use it somewhere and someone else will learn it and add it to their vocabulary, etc. ad infinitum. So a perfect example of language as virus is slang. Some new words spread so thoroughly that they become adopted into common language. For instance "cyberspace", "email" and "fuck". I think it is safe to say that the entirety of all languages developed similarly: words come into existence by creation, mutation and propagation.
See also my wacky conclusions: You are language.
Terence McKenna thinks that language will soon evolve into visible language. Maybe as soon as December 21, 2012.