Discoveries of new planets have revealed countless worlds much stranger than Earth. Some of these strange worlds don’t have stars; others are made out of diamonds. Will we ever find a planet like Earth, or are these distant worlds stranger than fiction?

Moving on to the Late Eocene period 36 million years ago and mammals have prospered and are now the largest creatures on land and sea. This is an era of animals like andrewsarchus, the biggest mammal carnivore ever to walk on land, and the brontotheres, small-brained herbivores. It is in the sea, however, that the most monstrous mammals of all can be found. We follow the fate of a female basilosaurus, a huge serpent-like early whale, but nothing like the gentle filter feeding whales of the 21st century. Four times the length of the great white shark, with jaws to match, she is every inch a killer.

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.

Since Caesar's days, Germanic warriors and Roman legionaries had often met in battle. Rome's power seemed invincible. But then, in the year 9 AD, the Germans mounted a rebellion.

David Attenborough reveals the surprising truth about the cold-blooded lives of reptiles and amphibians. These animals are as dramatic in combat, as colourful in their communication and as tender in their parental care as any other animals. Join giant courting crocodiles, jousting tortoises and bright red sumo-wrestling frogs in their sophisticated, solar-powered lives.

The series explores the impact of racism on a global scale and chronicles the shifts in the perception of race and the history of racism in Europe, the Americas, Australia and Asia. The first episode begins by assessing the implications of the relationship between Europe, Africa and the Americas in the 15th century. It considers how racist ideas and practices developed in key religious and secular institutions, and how they showed up in writings by European philosophers Aristotle and Immanuel Kant.