There's... a... mathematical equation for the decay of the past tense of English irregular verbs.
You know, I think I remember a guy on either The Daily Show or The Colbert Report (probably the latter) who talked about that. I think he was trying to document them. He mentioned one or two languages that currently have only one living speaker (I think one was in Australia).^ May be surprised to know thousands of existing languages will become extinct because there aren't enough people speaking them.