Thanks to new technologies combining genetics, ethology, geology and even particle physics, paleontologists can now recreate the missing branches of the tree of life. Because of this, it has been discovered that prehistoric mammals were more varied and numerous than previously thought.
The first episode introduces the viewers to the continent of Antarctica and the surrounding sea and islands, its glaciers and the icebergs that form from it. It describes how the continent changes throughout the seasons, as it effectively doubles in size in winter when the surrounding sea freezes over, "the greatest seasonal change that takes place on this planet".
As the Ganges nears the sea, it joins its mightiest tributary the Brahmaputra, creating a vast flood-prone delta. Here the bustling cities of Calcutta and Dhaka meet the wetlands, home to giant lizards and snakes, huge mean-eating crocodiles and forests full of monkeys. This is a story of human life persisting in wildly variable conditions in a domain that is still the preserve of the royal Bengal tiger.