Diarmaid MacCulloch's own life story makes him a symbol of a distinctive feature about Western Christianity - scepticism, a tendency to doubt which has transformed both Western culture and Christianity. In the final programme in the series, he asks where that change came from. He challenges the simplistic notion that faith in Christianity has steadily ebbed away before the relentless advance of science, reason and progress, and shows instead how the tide of faith perversely flows back in. Despite the attacks of Newton, Voltaire, the French Revolutionaries and Darwin, Christianity has shown a remarkable resilience. The greatest damage to Christianity was actually inflicted to its moral credibility by the two great wars of the 20th century and by its entanglement with Fascism and Nazism. And yet it is during crisis that the Church has rediscovered deep and enduring truths about itself, which may even be a clue to its future.

From dinosaurs to mammoths, when our ancient ancestors encountered the fossil bones of extinct prehistoric creatures, what did they think they were? Just like us, ancient peoples were fascinated by the giant bones they found in the ground. Historian Tom Holland goes on a journey of discovery to explore the fascinating ways in which our ancestors sought to explain the remains of dinosaurs and other giant prehistoric creatures, and how bones and fossils have shaped and affected human culture.
In Classical Greece, petrified bones were exhibited in temples as the remains of a long-lost race of colossal heroes. Chinese tales of dragons may well have had their origins in the great fossil beds of the Gobi desert. In the Middle Ages, Christians believed that mysterious bones found in rock were the remains of giants drowned in Noah's Flood.
Tom encounters a medieval sculpture that is the first known reconstruction of a monster from a fossil, and learns about the Native Americans stories, told for generations, which contained clues that led bone hunters to some of the greatest dinosaur finds of the nineteenth century.

Africa's wildest river is home to the most spectacular wildlife. Hippos fight for territory while herds of elephant, water buffalo and zebra depend on it for life. In the wet season the rains burst the riverbanks and everyone, including people, must move whilst fish swim through the villages. In the dry season the creatures fight over the few pools of water while predators prowl. At its heart it plunges over Victoria Falls and into wild ravines before draining into the Indian Ocean, where storm clouds cycle the water back into the heart of Africa.

Documentary-maker David Malone delves into the secrets of ocean waves. In an elegant and original film he finds that waves are not made of water, that some waves travel sideways and that the sound of the ocean comes not from water but from bubbles. Waves are not only beautiful but also profoundly important, and there is a surprising connection between the life cycle of waves and the life of human beings.

Dr Adam Rutherford takes the viewer on a rollercoaster ride as he explores the consequences of one of the biggest scientific projects of all time - the decoding of the entire human genome in 2000. In The Book of Life Adam discovers that every human carries the entire story of life on earth hidden in his or her DNA and sees how we are all linked directly to the origins of life and to the first creatures with backbones. He also investigates the implications of the fact that for much of its existence, the human race was an endangered species.

Dr Adam Rutherford shows how decoding the genome has led us to begin to understand the very process by which our DNA makes us different; how it makes each one of us on earth unique and influences who we are and the traits we have. He reveals how, as we try and understand the relationship between who we are and our genes, we stand at the beginning of the most exciting scientific journey of all time.