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 SheffieldJohn Edwards Faculty Fellow in Spanish at the University of OxfordAnd Julia McClure Lecturer in Late Medieval and Early Modern Global History at the University of GlasgowProducer: Simon Tillotson

Greg Jenner is joined by Dr Caroline Dodds Pennock and comedian Desiree Burch in the 15th century to learn all about the Columbian Exchange, which is often described as the start of globalisation. We go beyond the expeditions of Christopher Columbus to share the bigger story of a monumental exchange of plants, foods, animals, materials, people and culture across the continents. It’s also a life lesson on why you shouldn't set sail with a couple of cougars aboard your ship!Research by Roxy Moore Written by Emma Nagouse and Greg Jenner Produced by Emma Nagouse and Greg Jenner Assistant Producer: Emmie Rose Price-Goodfellow Project Management: Isla Matthews Audio Producer: Steve HankeyYou’re Dead To Me is a production by The Athletic for BBC Radio 4.

Travel back to the land of the Aztecs to discover that they’re not that dissimilar to the Tudors, but with more human sacrifices.Greg Jenner is joined by comedian Joel Dommett and historian Dr Caroline Dodds Pennock to ask just how much food can be traced back to the Aztecs? Was cannibalism really a respectful process? And at what age were Aztec children expected to contribute to the family? It’s history for people who don’t like history! Produced by Dan Morelle Script by Greg Jenner Research by Emma Nagouse assisted by Josh DanielsA Muddy Knees Media production for BBC Radio 4