The Goddess of the Earth
At this moment the plants in your garden are producing a gas which could set the planet on fire. Luckily, it won't happen - partly because of ancient bacteria in our guts! This idea forms part of a startlingly controversial theory put forward by Dr James Lovelock to explain how life on Earth has survived for three-and-a-half billion years. He argues that life itself actively manipulates the planet, ensuring that the oceans don't boil or freeze and that the atmosphere remains breathable. His name for this self-regulating system is
Gaia - the ancient Greeks' goddess of the Earth.
Narrator Paul Vaughan Film editor NICK RAYNER
Horizon editor GRAHAM MASSEY Written and produced by JOHN GROOM