Iran Remembers Revolution 40 Years On

Iran is marking and celebrating a significant milestone: the Islamic Republic is 40 years old. We explore the revolution's successes and challenges - and we hear the story of Jason Rezaian, a journalist who spent 544 days in an Iranian prison.

Also in the programme - why our planet's insects could vanish in a hundred years.

(Photo: Iranians march during a ceremony celebrating the 40th anniversary of 1979 Islamic Revolution. Credit: Getty Images)