BBC - How to Grow a Planet. Part 3: The Challenger (2012)

Stars: Iain Stewart

Geologist Ian Stewart explain in three stages of natural history the crucial interaction of our very planet's physiology and its unique wildlife. Biological evolution is largely driven bu adaptation to conditions such as climate, soil and irrigation, but biotopes were also shaped by wildlife changing earth's surface and climate significantly, even disregarding human activity.

Episode 3: In the third episode, Iain discovers the remarkable impact of just one plant: grass. On the savannah of South Africa he sees how grass unleashed a firestorm to fight its greatest enemy, the forests. He shows how cutting your finger on a blade of grass shows us how it transformed life in the oceans. In Senegal, he meets the cleverest chimps in the world. And, in the ruins of the oldest temple on Earth, he tells the extraordinary story of how grass triggered human civilisation.