How a bloody 1960s revolution changed East Africa. We hear an eyewitness account and talk to Professor Emma Hunter of Edinburgh University. Plus the birth of ecotourism in Costa Rica, the post-war origin of the World Health Organisation, the man who created the world's first portable defibrillator, and remembering the artist Christo.

PHOTO: Ugandan revolutionary and self-styled Field Marshal John Okello (1937 - 1971), leader of the Afro-Shirazi anti-Arab coup in Zanzibar, circa 1964. (Photo by Pix/Michael Ochs Archives/Getty Images)