For many years, linguists (especially in the US) have discussed concepts such as Language Universals and Universal Grammar (UG), in an attempt to find features or patterns shared by all languages in the world. The idea seems interesting but... is there anything really 'universal' in language? In a recent article, Nicholas Evans and Stephen Levinson have reviewed the concept of language universals, offering a great deal of examples that contradict even the most basic of the universals proposed by Greenberg and other linguists. According to the authors of the article, the only thing that can be established is a series of statistical tendencies (following Greenberg's nomenclature) that may be inferred from typological analysis. As for Chomsky's UG, I personally think it is one of the most irrelevant concepts ever devised in linguistics.
So it seems that there might be nothing really 'universal' about human language, but what about human communication? In two recent posts (here and here), I put forward some ideas about the origin of language and grammar. In my opinion, the main difference between human and non-human 'language' is the fact that we can use the narrative/descriptive vs imperative contrast in our utterances; in fact, there's no way we can produce an utterance ouside these parameters. If I say a word or a sentence, I'm either narrating/describing something or telling someone to do something, or maybe a combination of both, whereas in non-human communication, it is not clear that this contrast is used meaningfully, or consciously. At first, I thought of it in terms of 'language' or 'grammar', but then I realized that it is present in both verbal and non-verbal types of human communication. Whenever we communicate, with words or with gestures, we are actually creating narrative, descriptive or imperative contexts, and our listeners have an ability to decode this variety of meanings. The grammatical components associated with this contrast, e.g. the various moods (imperative, optative, indicative, etc.) were probably preceded by a non-verbal 'grammar' that set the foundations for human oral language as we know it. Without this previous development, which may have originated at a very early stage in our development as a species, our verbal communication would be limited to a simple set of calls.
Now, what about universals? Is it possible to find them at the level of human communication? I can see at least two possible candidates:
1. All human groups use verbal language, unless their members are physically impaired to develop this ability, e.g. deaf and dumb people.
2. In all types of human communication, both verbal and non-verbal, a significant contrast is established between narrative/descriptive and imperative contents.
Sources of the pictures, (added on Jan31, 2010): 1st and 3rd, from Inimagine; 2nd picture, from this interesting article in PNAS.