Wow; thanks, olly, for posting that great article. I hope Anu reads it--I know he'd be interested.

Someone posited this: Suppose everyone woke up tomorrow fluently speaking, writing, and reading the same one language, in addition to the one(s) they now speak. Prof. Hagège responds in part, It would be infelicitous, because the cultural, and hence linguistic, diversity of the world is the main factor of its richness. A one language world would be an unbearable world, in which people would be bored to death.

Does everyone here agree with that?