Melvyn Bragg and guests discuss the remarkable diversity of the animals that dominated life on land in the Triassic, before the rise of the dinosaurs in the Jurassic, and whose descendants are often described wrongly as 'living fossils'. For tens of millions of years, the ancestors of alligators and Nile crocodiles included some as large as a bus, some running on two legs like a T Rex and some that lived like whales. They survived and rebounded from a series of extinction events but, while the range of habitats of the dinosaur descendants such as birds covers much of the globe, those of the crocodiles have contracted, even if the animals themselves continue to evolve today as quickly as they ever have. With Anjali Goswami Research Leader in Life Sciences and Dean of Postgraduate Education at the Natural History Museum Philip Mannion Lecturer in the Department of Earth Sciences at University College London And Steve Brusatte Professor of Palaeontology and Evolution at the University of Edinburgh Producer Simon Tillotson

Melvyn Bragg and guests discuss the debate in Valladolid, Spain in 1550, over Spanish rights to enslave the native peoples in the newly conquered lands. Bartolomé de Las Casas (pictured above), the Bishop of Chiapas, Mexico, was trying to end the encomienda system in which those who now owned the land could also take the people in forced labour. Juan Gines Sepulveda, a philosopher, argued for the colonists' property rights over people, asserting that some native Americans were 'natural slaves' as defined by Aristotle. Valladolid became seen as the first open attempt by European colonists to discuss the ethics of slavery, and Las Casas became known as 'Saviour of the Indians' and an advocate for human rights, although for some time he argued that African slaves be imported to do the work in place of the native people, before repenting. With Caroline Dodds Pennock Senior Lecturer in International History at the University of Sheffield John Edwards Faculty Fellow in Spanish at the University of Oxford And Julia McClure Lecturer in Late Medieval and Early Modern Global History at the University of Glasgow Producer: Simon Tillotson

Melvyn Bragg and guests discuss one of the outstanding French writers of the twentieth century. The novels of Sidonie-Gabrielle Colette (1873 - 1954) always had women at their centre, from youth to mid-life to old age, and they were phenomenally popular, at first for their freshness and frankness about women’s lives, as in the Claudine stories, and soon for their sheer quality as she developed as a writer. Throughout her career she intrigued readers by inserting herself, or a character with her name, into her works, fictionalising her life as a way to share her insight into the human experience. With Diana Holmes Professor of French at the University of Leeds Michèle Roberts Writer, novelist, poet and Emeritus Professor of Creative Writing at the University of East Anglia And Belinda Jack Fellow and Tutor in French Literature and Language at Christ Church, University of Oxford Producer: Simon Tillotson

Melvyn Bragg and guests discuss the great epic poem attributed to Homer, telling the story of an intense episode in the Trojan War. It is framed by the wrath of the Greek hero Achilles, insulted by his leader Agamemnon and withdrawing from the battle that continued to rage, only returning when his close friend Patroclus is killed by the Trojan hero Hector. Achilles turns his anger from Agamemnon to Hector and the fated destruction of Troy comes ever closer. With Edith Hall Professor of Classics at King's College London Barbara Graziosi Professor of Classics at Princeton University And Paul Cartledge A.G. Leventis Senior Research Fellow and Emeritus Professor of Greek Culture at Clare College, Cambridge Producer: Simon Tillotson.

Melvyn Bragg and guests discuss the ideas and life of the German theologian, born in Breslau/Wroclaw in 1906 and killed in the Flossenbürg concentration camp on 9th April 1945. Bonhoeffer developed ideas about the role of the Church in the secular world, in particular Germany after the Nazis took power in 1933 and demanded the Churches' support. He strongly opposed anti-Semitism and, with a role in the Military Intelligence Department, took part in the resistance, plotting to kill Hitler and meeting with contacts in the Allies. Bonhoeffer's ideas on Christian ethics and the relationship between Christianity and humanism spread more widely from the 1960s with the discovery of unpublished works, including those written in prison as he awaited execution. With Stephen Plant Dean and Runcie Fellow at Trinity Hall at the University of Cambridge Eleanor McLaughlin Lecturer in Theology and Ethics at the University of Winchester and Lecturer in Ethics at Regent’s Park College at the University of Oxford And Tom Greggs Marischal Chair of Divinity at the University of Aberdeen Producer: Simon Tillotson