But DIRTY language. So don't read if you're sensitive of disposition.
One of the most fascinating aspects of human language, as a syntactician, is what I call asyntactic language. That is, elements of language that don't fit in to syntax. And there are a lot of these elements, which we tend not to think of, because they get used too often to be truly noticed. Everyone probably had grammar classes, where we were taught some fairly rubbish things. For instance, 'a noun is a person, place, thing, or idea'. Right. So what's 'destruction'? It's an action, right? Actions are verbs, according to prim Miss Smith and her HBJ textbook. But is 'to seem' an action? Many verbs denote states...feel, love, look, etc. So, here's the first assumption: everything we think we know about language is either wrong, or so simplistic as to be useless.
The only good diagnostic for category (Noun, Verb, Adjectival, Preposition, et al). is modification and placement. So we know it's a noun if it acts like a noun. So in a sentence like 'the burning of books is disgusting', burning is a noun...it takes a determiner, and only nouns do that. Also, it takes an adjective and not an adverb: the constant burning of books vs. constantly burning books.
Right. With me so far? But some words are screwy. Greeting words, like 'hello, good bye' etc. They have no category. Exclamations...what is 'ouch'? A verb? Nah.
Finally, what are obscenities? If I stub my toe and say 'damn!', am I really asking for something to be damned? If I say, 'get in the damn house', the standard argument would say that I'm eliding the end of 'damned', which is a participial adjective. But is it? I can say 'I don't give a damn' which is quite clearly a noun.
Most interestingly, in English, only a few words can fill the role of infix. Many languages have these, but in English, they're all swear words. The best in American English is 'fucking'. If you ask me if I want a beer, I can reply 'abso-fucking-lutely'. If you tell me the Washington Nationals are in first place in the NL East, I can say 'un-fucking-believable'.
But note that this is not random infixing. It can go in one place and one place only. It gets technical here, but it has to do with the stressed syllable. So if you were to say 'ab-fucking-solutely' or 'absolute-fucking-ly', you'd at best get some strange looks.
What am I getting at? This to me fits in nicely with some of Derek Bickerton's work on proto-language. That is, the asyntactic language humans had before syntax evolved (and I'll post on both language acquisition and evolution soon). Language (and communication systems in general) seem to evolve with simple, context neutral expressions, with no displacement. So in this world of protolanguage, if I say 'meat', it could mean 'you and I will go hunt' but never 'Tom and I will go hunt.' If I say 'cook' it means 'the women and children will cook the food', never 'will there be food?' or 'who oh who will cook?'. This is the bee-dance stage of human language. What's interesting is that we still have it: If I say 'FUCK!' you'll know I'm upset. It has no context, and no grammar (I should add I'm referring here only to the expletive usage; obviously, 'fuck' as a verb meaning 'have intercourse with' is different).
Some interesting research comes from people who have suffered strokes, or brain trauma. Depending on where the damage is, you may lose speech. But not all language; if you suffer trauma near Broca's region, you're likely to lose a lot of your grammatical capacity. You'll probably still have the 'big' words with lots of meaning, but the grammatical words (auxiliary verbs, prepositions, determiners, etc.) will be gone. Other impairments allow fluid speech with no real meaning (often called 'verbal diarrhea syndrome', and it's intimidating to hear, I assure you.). But almost never do people lose the capacity to swear.
I haven't got on to the subject of Tourette's yet, but that's more evidence for an extralinguisitc, possibly primitive, language module with a limited inventory...obscenities, greeting words, and other verbal space fillers (phatic speech). But I think it's nice evolution left us with a ready response when we stub our toes.
UPDATE: A colleague and I were discussing this phemonenon today over afternoon pints (the best kind of pints, if you ask me) and are considering writing a conference paper on it. If so, I shall insist it be called 'A discourse on the nature of fucking'.