In the programme, Horizon meets a groups of scientists who are trying to work out the secrets of speech, which includes a father who filmed every second of his son's first three years in order to discover how we learnt to talk, the autistic savant who could speak more than 20 languages, and the first scientist to identify a gene that makes speech possible.
We can also listen to Noam Chomsky, the first linguist to suggest that our ability to talk is innate. A unique experiment shows how a new language can emerge in just one afternoon, in an attempt to understand where language comes from and why it is the way it is.
On the downside, however, no subtitles available, I'm afraid.