Professor Fortey looks at the Ice Age. 2.8 million years ago - triggered by slight changes in the Earth's orbit around the sun and shifts in its ocean currents - the world began to cool. Within a few thousand years much of the planet was shrouded in a dense cloak of ice that would come and go until only 10,000 years ago. We call this age of ice - the Pleistocene Age - and it transformed the hierarchy of nature. This is the story of how a few specialist species that evolved to live in the biting cold survived into the present day.

Professor Fortey focuses on the 'KT boundary'. 65 million years ago, a 10 km diameter asteroid collided with the Earth and saw the end of the long reign of the dinosaurs. He investigates the lucky breaks and evolutionary adaptations that allowed some species to survive the disastrous end of the Cretaceous Age when these giants did not.

Professor Fortey focuses on a series of cataclysms over a million-year period 250 million years ago.