Horizon: How Mad Are You?: How Mad Are You? Part 1 is no longer available. Programmes are available for a limited number of days after broadcast. Why?
Alan Davies attempts to answer the proverbial question: how long is a piece of stri...
Horizon investigates speech, a phenomenon unique to humans, which remains a mystery...
What was there before the Big Bang? Black holes could hold the answer. (R)
Three people with untreatable conditions see if, within their lifetime, they can... (R)
The search for answers to one of science's greatest mysteries: how do we know wh... (R)
Addiction expert John Marsden explores our relationship with alcohol. (R)
Alex Riley sets out to unearth the horrors that could be in his meaty snacks. (R)
Actress Mikyla Dodd takes a tour through a whole range of dieting disasters. (R)
Chris Packham and Kate Humble share their adventures in a wildlife-rich cider or... (R)
Chris and Kate say goodbye to the summer's migrants and hello to the autumn arri... (R)
A look at how some animals and plants go to extremes to give themselves a chance... (R)
Chris and Kate are at a wildlife hospital helping to care for sick and injured a... (R)
A look at the strategies used by reptiles and amphibians to conquer their shortc... (R)
Chris Packham and Kate Humble are in north Norfolk to witness the 'knot spectacl... (R)
Ray explores Canada's vast Boreal Forest and unlocks the secrets of this forgott... (R)
How mammals dominate the planet through having warm blood and by caring for thei... (R)
Jimmy tries to discover what really goes into supermarket sandwiches. (R)
A portrait of the lives of black bears in northern Minnesota, with biologist Lyn... (R)
Chris Packham and Kate Humble are in Gloucestershire for Halloween week. (R)
Ray tells the story of the British fur trade company that opened up Canada. (R)
A look at various fish species including sea dragon, fringehead and Hawaiian gob... (R)
Jimmy tries to discover what happens to milk before it arrives on the supermarke... (R)
A tale of life on the Zambezi River, set against the epic backdrop of Victoria F... (R)
Chris and Kate are in the Lake District to witness a British wood at its seasona... (R)
Ray follows in the footsteps of British pioneer Samuel Hearne on his epic 1,000-... (R)