Sir David Attenborough on un-tameable polar bears
26 October 2011 Last updated at 16:39 BST
Sir David Attenborough's new series Frozen Planet looks at life on the North and South Poles and the effects of global warming.
The seven-part series recorded the endurance hunting of grey wolves, stone stealing penguins and bouncing seals.
Sir David told BBC Radio 5 live about the dangers of powerful polar bears in the wild.
Frozen Planet starts on 26 October at 21:00 BST on BBC One
Richard Bacon broadcasts Monday to Thursday 14:00 to 1600 on BBC Radio 5 live.
To hear more Radio 5 live highlights, please visit the best bits (www.bbc.co.uk/5live/bestbits) page.