The Fish-Tetrapod Transition

Melvyn Bragg and guests discuss one of the greatest changes in the history of life on Earth. Around 400 million years ago some of our ancestors, the fish, started to become a little more like humans. At the swampy margins between land and water, some fish were turning their fins into limbs, their swim bladders into lungs and developed necks and eventually they became tetrapods, the group to which we and all animals with backbones and limbs belong. After millions of years of this transition, these tetrapod descendants of fish were now ready to leave the water for a new life of walking on land, and with that came an explosion in the diversity of life on Earth.The image above is a representation of Tiktaalik Roseae, a fish with some features of a tetrapod but not one yet, based on a fossil collected in the Canadian Arctic.WithEmily Rayfield Professor of Palaeobiology at the University of BristolMichael Coates Chair and Professor of Organismal Biology and Anatomy at the University of ChicagoAnd Steve Brusatte Professor of Palaeontology and Evolution at the University of EdinburghProducer: Simon Tillotson

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Spanning history, religion, culture, science and philosophy, In Our Time from BBC Radio 4 is essential listening for the intellectually curious. In each episode, host Melvyn Bragg and expert guests explore the characters, events and discoveries that have shaped our world. History fans can learn about pivotal wars and societal upheavals, such as the rise and fall of Napoleon, the Sack of Rome in 1527, and the political intrigue of the Russian Revolution. Those fascinated by the lives of kings and queens can journey to Versailles to meet Marie Antoinette and Louis XIV the Sun King, or to Ancient Egypt to meet Cleopatra and Nerfertiti. Or perhaps you’re looking to explore the history of religion, from Buddhism’s early teachings to the Protestant Reformation. If you’re interested in the stories behind iconic works of art, music and literature, dive in to discussions on the artistic genius of Michelangelo's Sistine Chapel and Van Gogh’s famous Sunflowers. From Gothic architecture to the works of Shakespeare, each episode of In Our Time offers new insight into humanity’s cultural achievements. Those looking to enrich their scientific knowledge can hear episodes on black holes, the Periodic Table, and classical theories of gravity, motion, evolution and relativity. Learn how the discovery of penicillin revolutionised medicine, and how the death of stars can lead to the formation of new planets. Lovers of philosophy will find episodes on the big issues that define existence, from free will and ethics, to liberty and justice. In what ways did celebrated philosophers such as Mary Wollstonecraft and Karl Marx push forward radical new ideas? How has the concept of karma evolved from the ancient Sanskrit texts of Hinduism to today? What was Plato’s concept of an ideal republic, and how did he explore this through the legend of the lost city of Atlantis? In Our Time celebrates the pursuit of knowledge and the enduring power of ideas.