This is the third and last of Sir David's great natural history books based on his TV series and competes his survey of the animal world that began with 'Life on Earth' and continues with 'Living Planet'. In 'Life on Earth', Sir David showed how each group of animals evolved. In 'Living Planet' he looked at the way they have adapted to the whole range of habitats in which they live. Now, in 'The Trials of Life', he completes the story by revealing how animals behave - and why.