Why do we talk?.

Speech and language differentiate us from all other animal species yet how we learn to speak is still largely unknown. This fascinating documentary looks at a variety of research projects all aiming to understanding why and how we learn to talk. Cognitive scientist Deb Roy has set up the Speech Home Project in which he analyses in minute detail the processes by which his own infant son begins to acquire language. Cathy Price studies the brain of Steve Steere, who had a stroke following a bicycling accident which left him unable to speak, to try to work out where his missing speech centres are. William Fifer is experimenting with speech sounds and newborn babies - his research shows that newborns respond in a totally different way to the voice of their mother than they do to any other voice. Language specialist Gary Morgan is working with Christopher, an autistic man with an astonishing ability to learn languages - we see Christopher learn a new language. Noam Chomsky believes we have an inate ability to speak - if this is so, would a child brought up without ever hearing language learn to speak by themselves? Ofer Tchernichovski is studying birdsong in finches that have been separated from their father's song - they grow up unable to copy it. However, over subsequent generations the birds develop a new language which begins to have its own form and structure. Faraneh Vargha-Khadem has been studying a family who all have the same genetic speech defect - the K family speak as though they are deaf even though all of their other neurological functions are entirely normal. Vargha-Khadem has isolated a gene, Fox P2, which controls our ability to shape words, this is faulty in the K family. Language specialist Mark Pagel reveals his experiment in which a group of volunteers independantly form a new language, unconsciously shaping its structure and meaning.