Comprehensive report by veteran science writer Davis (Mapping the Code, 1990, etc.) on the glories and mysteries of language. Evidence that animals can talk is, Davis says, ``scant at best'': Language remains a distinctively human trait and perhaps our crowning achievement, and it may play a key role in the creation of the sense of an ``I,'' by which we know ourselves and the world. According to Davis, language is at least 100,000 years old, although its origins remain misty. We do know that all extant languages are equally complex (no so-called ``primitive'' language exists) and that all languages evolve--a process for which Davis uses English (the ``single most important spoken and written language'') as a fascinating case history, tracing how ``dramatic changes in vowel pronunciation'' turned Chaucer's English into the language spoken today. This sort of study arises from the blossoming of linguistics, which Davis traces from its origins in ancient Greece and India through the breakthrough work, in the 18th century, of Sir William Jones (who first noticed that Sanskrit, Greek, and Latin are related) to the transformational grammar of Noam Chomsky, who perceives innate language structures in the mind. But minds require brains, and Davis explains in great detail how the brain stores and processes information, as well as how it produces language. It turns out that language abilities are spread throughout our gray matter and that, in multilingual people, different areas of the brain handle different languages. The stages of language acquisition in infants are also covered--from crying to gurgling to babbling to real talking (which begins at about one year). Seven appendices offer a bounty of language miscellany, from a pronunciation guide for phonetic symbols to a chart of Indo-European tongues. A first-rate overview of language from A to Z, and then some.