Friday, May 16, 2008

Language: No current theory of its origin is worth much

Further to the question of the origin of language, in "Selective scenarios for the emergence of natural language"* Szabolcs Számadó and Eörs Szathmáry opine,
Explaining the evolution of human language is likely to remain a challenge for the coming decade. As we have discussed, there is no single theory that could sufficiently answer all the questions about honesty and groundedness, power of generalisation, and uniqueness. Table 1 summarises these criteria. As one can see, most of the theories fail to answer most of the questions. Perhaps the easiest criterion to fulfil is shared interest, as there are several social situations that assume shared interest between communicating parties (such as hunting or contact calls). There are only two theories, 'tool making' and 'hunting' 22 and 26, that do significantly better than the others as they can answer three out of the four questions asked of them (Table 1). Thus, it might be tempting to say that some combination of the two could provide a series of selective scenarios that would fit all of our criteria. The most notable conclusion, however, is that all the theories fail to explain the uniqueness of human language. Thus, even though indirect evidence strongly suggests that the evolution of human language was selection limited, it remains difficult to envisage a scenario that would show why.
Theirs is, on the whole, a glum look:
The recent blossoming of evolutionary linguistics has resulted in a variety of theories that attempt to provide a selective scenario for the evolution of early language. However, their overabundance makes many researchers sceptical of such theorising. Here, we suggest that a more rigorous approach is needed towards their construction although, despite justified scepticism, there is no agreement as to the criteria that should be used to determine the validity of the various competing theories. We attempt to fill this gap by providing criteria upon which the various historical narratives can be judged. Although individually none of these criteria are highly constraining, taken together they could provide a useful evolutionary framework for thinking about the evolution of human language.
They go on to hope that Darwin's natural selection will answer the question, but it is hard to see how. Natural selection eliminates life forms that express genes that do not help them survive. It is not known to produce ideas that must be expressed in language.

*(Trends in Ecology & Evolution, Volume 21, Issue 10 , October 2006, Pages 555-561)