BBC RADIO 4 - In our time

Melvyn Bragg and guests discuss the life and ideas of Frederick Douglass, who was born into slavery in Maryland in 1818 and, once he had escaped, became one of that century's most prominent abolitionists. He was such a good orator, his opponents doubted his story, but he told it in grim detail in 1845 in his book 'Narrative of the Life of Frederick Douglass, an American Slave.' He went on to address huge audiences in Great Britain and Ireland and there some of his supporters paid off his owner, so Douglass could be free in law and not fear recapture. After the Civil War and the abolition of slavery, he campaigned for equal rights for African-Americans, arguing against those such as Lincoln who had wanted freed slaves to leave America and found a colony elsewhere. "We were born here," he said, "and here we will remain." With Celeste-Marie Bernier Professor of Black Studies in the English Department at the University of Edinburgh Karen Salt Assistant Professor in Transnational American Studies at the University of Nottingham And Nicholas Guyatt Reader in North American History at the University of Cambridge Producer: Simon Tillotson.

Melvyn Bragg and guests discuss how some bats, dolphins and other animals emit sounds at high frequencies to explore their environments, rather than sight. This was such an unlikely possibility, to natural historians from C18th onwards, that discoveries were met with disbelief even into the C20th; it was assumed that bats found their way in the dark by touch. Not all bats use echolocation, but those that do have a range of frequencies for different purposes and techniques for preventing themselves becoming deafened by their own sounds. Some prey have evolved ways of detecting when bats are emitting high frequencies in their direction, and some fish have adapted to detect the sounds dolphins use to find them. With Kate Jones Professor of Ecology and Biodiversity at University College London Gareth Jones Professor of Biological Sciences at the University of Bristol And Dean Waters Lecturer in the Environment Department at the University of York Producer: Simon Tillotson.

Melvyn Bragg and guests discuss the Spanish poet and playwright Federico Garcia Lorca (1898-1936), author of Blood Wedding, Yerma and The House of Bernarda Alba, who mixed the traditions of Andalusia with the avant-garde. He found his first major success with his Gypsy Ballads, although Dali, once his close friend, mocked him for these, accusing Lorca of being too conservative. He preferred performing his poems to publishing them, and his plays marked a revival in Spanish theatre. He was captured and killed by Nationalist forces at the start of the Civil War, his body never recovered, and it's been suggested this was punishment for his politics and for being openly gay. He has since been seen as the most important Spanish playwright and poet of the last century. With Maria Delgado Professor of Creative Arts at the Royal Central School of Speech and Drama, University of London Federico Bonaddio Reader in Modern Spanish at King’s College London And Sarah Wright Professor of Hispanic Studies and Screen Arts at Royal Holloway, University of London Producer: Simon Tillotson

Melvyn Bragg and guests discuss the people, plants and animals once living on land now under the North Sea, now called Doggerland after Dogger Bank, inhabited up to c7000BC or roughly 3000 years before the beginnings of Stonehenge. There are traces of this landscape at low tide, such as the tree stumps at Redcar (above); yet more is being learned from diving and seismic surveys which are building a picture of an ideal environment for humans to hunt and gather, with rivers and wooded hills. Rising seas submerged this land as glaciers melted, and the people and animals who lived there moved to higher ground, with the coasts of modern-day Britain on one side and Denmark, Germany, The Netherlands, Belgium and France on the other. With Vince Gaffney Anniversary Professor of Landscape Archaeology at the University of Bradford Carol Cotterill Marine Geoscientist at the British Geological Survey And Rachel Bynoe Lecturer in Archaeology at the University of Southampton Producer: Simon Tillotson

Melvyn Bragg and guests discuss why Athenians decided to send a fast ship to Lesbos in 427BC, rowing through the night to catch one they sent the day before. That earlier ship had instructions to kill all adult men in Mytilene, after their unsuccessul revolt against Athens, as a warning to others. The later ship had orders to save them, as news of their killing would make others fight to the death rather than surrender. Thucydides retells this in his History of the Peloponnesian War as an example of Athenian democracy in action, emphasising the right of Athenians to change their minds in their own interests, even when a demagogue argued they were bound by their first decision. With Angela Hobbs Professor of the Public Understanding of Philosophy at the University of Sheffield Lisa Irene Hau Senior Lecturer in Classics at the University of Glasgow And Paul Cartledge Emeritus AG Leventis Professor of Greek Culture, University of Cambridge and Senior Research Fellow of Clare College Producer: Simon Tillotson