Human language is a weird communication system: it has more in common with birdsong than the calls of other primates. In this clear and non-technical overview, Jean Aitchison explores why it evolved and how it developed. She likens the search to a vast prehistoric jigsaw puzzle, in which numerous fragments of evidence must be assembled, some external to language, such as evolution theory, animal communication; others internal, including child language, pidgins and creoles, and language change. She explains why language is so strange, outlines recent theories about its origin, and discusses possible paths of evolution. Jean Aitchison is the Rupert Murdoch Professor of Language and Communication at Oxford University. She gave the 1996 BBC Reith lectures The Language Web.