Sagan discusses the story of the Heike crab and artificial selection of crabs resembling samurai warriors, as an opening into a larger discussion of evolution through natural selection (and the pitfalls of intelligent design). Among the topics are the development of life on the Cosmic Calendar and the Cambrian explosion; the function of DNA in growth; genetic replication, repairs, and mutation; the common biochemistry of terrestrial organisms; the creation of the molecules of life in the Miller-Urey experiment; and speculation on alien life (such as life in Jupiter's clouds). In the Cosmos Update ten years later, Sagan remarks on RNA also controlling chemical reactions and reproducing itself and the different roles of comets (potentially carrying organic molecules or causing the Cretaceous–Paleogene extinction event).

Evolution tells us that all life exists for only one purpose: to reproduce. But is that all there is? How could such a simple imperative lead us to create great art and civilizations? A new theory suggests that instead of passing on genes, our ultimate purpose is to process and pass on information. We are the universe figuring itself out. Scientists dig deep into DNA, chemistry, technology and engineering to find the meaning of life. One thing is certain: living is easier if you find a reason for living.

(Click CC for English subtitles) Four Finnish cave divers face their worst nightmare when two of their friends drown deep inside an underwater cave in Norway. When the official recovery operation is called off by the Norwegian and British authorities after being deemed too risky, the friends set out on a secret mission to retrieve the bodies themselves. "Diving into the Unknown" isn’t just the dramatic story of a life-threatening mission. It is also a story about unconditional friendship that truly runs deep. While each member of the team has years of experience exploring dangerous deep-sea caves, together they are about to face the biggest challenge of their lives. To make it out alive, they will need to be able to rely on each other every second of the way. And the physical demands of this operation will pale in comparison to the psychological toll it will take on everyone involved. With footage from the actual accident and multiple cameras both above water and deep below the surface, this film follows the breathtaking recovery mission from beginning to end.

Dr Michael Scott examines the vital role played by the Romans in the preservation of Greek drama and in the history of theatre. He explores how the Romans absorbed Greek theatre and adapted it to their own, very Roman, ends and looks at how this famous empire provides one of the crucial connections between our modern drama and the great plays of the ancient Greeks.

The Dutch Golden Age saw map-making reach a fever pitch of creative and commercial ambition. This was the era of the first ever Atlases - elaborate, lavish and beautiful. This was the great age of discovery and marked an unprecedented opportunity for mapmakers who sought to record and categorise the newly acquired knowledge of the world. Rising above the many mapmakers in this period was Gerard Mercator, inventor of the Mercator projection, who changed mapmaking forever when he published his collection of world maps in 1598 and coined the term 'Atlas'. The programme looks at some of the largest and most elaborate maps ever produced, from the vast maps on the floor of the Royal Palace in Amsterdam, to the 24 volume atlas covering just the Netherlands, to the largest Atlas in the world, The Klencke Atlas. It was made for Charles II to mark his restoration in 1660. But whilst being one of the British Libraries most important items, it is also one of its most fragile so hardly ever opened. This is a unique opportunity to see inside this enormous and lavish work, and see the world through the eyes of a King.

Iain explores man's relationship with fire. He begins by embarking on an extraordinary encounter with this terrifying force of nature - a walk right through the heart of a raging fire. Fire has long been our main source of energy and Iain shows how this meant that the planet played a crucial role in Britain's industrial revolution, whilst holding China's development back. Along the way he dives in a mysterious lake in Oregon, climbs a glacier of salt, crawls through an extraordinary cave in Iran and takes a therapeutic bath in crude oil.