DYING WORDS by Nicholas Evans makes a case that the rapid disappearance of languages around the world risks depriving the human race of vital knowledge. Over the past decade or so, a number of books have been published about language diversity in danger and why it matters, but DYING WORDS is perhaps the most theoretically detailed survey so far. In spite of suggestions in the introduction that Evans is writing for a fairly popular audience (for example, he describes phonetic transcription and glossing as if the reader doesn't know), it swiftly becomes clear that he is writing for a university audience that has at least basic training in linguistics.
If you don't have such formal training, you'll probably be over your head. Instead, try K. David Harrison's books The Last Speakers, written for the general public, or ASIN:0195372069 When Languages Die, more theoretical but accessible to dilettantes.
DYING WORDS is centered around four central reasons why the death of undocumented or insufficiently documented languages is a loss:
* Languages may contain data on the natural world that scientists have not yet discovered. This theme forms a large part of other books on the threat to language diversity, but Evans gives it the least attention. Still, he does cite several recent cases where botanists or zoologists were led to new discoveries after encountering speakers of indigenous languages.
* By looking at a wide array of languages, we can discern what ways of speaking can, through common use, become grammaticalized, that is, become obligatory in discourse.
* There are still undeciphered writing systems, but if descendants of the language inscribed in them still survive today, they can provide vital clues for decipherment.
* Lesser-known languages have provided key data for exploring the relationship between language and cognition, such as the infamous Sapir-Whorf hypothesis. Here Evans draws heavily on recent descriptions of Australian Aboriginal languages that require the speaker to always keep his geographical bearings (as spatial expressions require reference to compass points)
* Languages are inseparate from their poetic traditions, and evidence from smaller languages reveals mankind's capacity for poetic techniques features that may not be attested in cultures documented to date.
DYING WORDS will aid budding linguists to understand the importance of language diversity so that they can then make their case to the public. However, it has its flaws. One issue, as I mentioned before, is that Evans is clearly writing for an audience trained in linguistics, but he still laboriously explains concepts that such readers would have already learnt very early on (such as IPA and the comparative method).
There are other points where the book could have used more attention from the editor. Early in the book Evans claims that the name "Roma" for the Gypsies is taken from their residence in the Byzantine (or Eastern Roman) Empire, but in a later chapter he notes that the name Roma was brought from India and related communities in the Middle East also have variations of the name. At one point he says Coptic may have survived until the 19th century in some places, and later he calls it "extinct in everyday life for a thousand years".
Still, for readers who want to see a case for language diversity made especially on the basis of the study of typology and universals, there is some valuable material here. And if you enjoyed Guy Deutscher's THROUGH THE LANGUAGE GLASS, Evans examines some of the same unusual languages.