Misha Glenny and guests discuss one of the most remarkable scientific discoveries of the 20th century: the archaea microorganisms. In the 1970s the American microbiologist Carl Woese (1928-2012) realised that the tiny bacteria-sized organisms he was studying were not actually bacteria but from an entirely different branch of the tree of life. It became clear that archaea, as he named them, share aspects of the cells in all plants and animals even if they often live in places where other life struggles including salty lakes, acidic pools, under the sea bed and in the gut. While aspects of what followed from Woese are still under debate, further discoveries suggest that life on Earth has been on a journey of separation and reunion: that the first cells developed into bacteria and archaea billions of years ago and that some of those later combined to form the complex cells from which we are made. With Christa Schleper Professor of Genetics and Microbiology at the University of Vienna Thorsten Allers Professor of Archaeal Genetics at the University of Nottingham And Buzz Baum Group leader at the MRC Laboratory of Molecular Biology in Cambridge Producer: Simon Tillotson Reading list: John Archibald, One Plus One Equals One: Symbiosis and the evolution of complex life (Oxford University Press, 2014) Buzz Baum, ‘I’: A Biography of the Biological Self (Allen Lane, forthcoming 2027) Franklin M. Harold, In Search of Cell History: The Evolution of Life's Building Blocks (University of Chicago Press, 2014) Nick Lane, Power, Sex, Suicide: Mitochondria and the Meaning of Life (Oxford University Press, 2005) David Quammen, The Tangled Tree: A Radical New History of Life (Simon & Schuster, 2018) Jan Sapp, Evolution by Association: A History of Symbiosis (Oxford University Press, 1994) In Our Time is a BBC Studios Production 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 Misha Glenny and expert guests explore the characters, events and discoveries that have shaped our world.