"Nothing in the natural world makes sense - except when seen in the light of evolution" believes David Attenborough. Charles Darwin's theory of evolution was "the best idea anyone has ever had".

This personal insight into Darwin's 'dangerous idea' from the world's favourite naturalist explores why it is now more important than ever.

Darwin's theory – that life has evolved over millions of years by natural selection – has become so much a 'part of the furniture' in our scientific world that we're in danger of taking it for granted.

But it has never been more important to applaud Darwin's 'unsurpassingly brilliant' insight, or to re-affirm its importance to our entire understanding of how the world works.

David Attenborough is a passionate Darwinian. He sees evolution as the cornerstone of all his thinking; Charles Darwin's ideas have permeated everything David has ever filmed or written.

In this one-hour special, Tree of Life, David asks three key questions: How, and why, did Darwin come up with his theory? Why do we think he was right? And why is it more important now than ever before?

To answer these questions, David takes us on a journey through the last 200 years, tracking the changes in our understanding of the natural world. Even in David's own childhood, there were still many unanswered questions to the theory of evolution.

But since Darwin's time, major scientific discoveries in biology, geology, palaeontology and genetics have all served to underpin and strengthen the evidence for his revolutionary and controversial idea. Today, the pieces of the puzzle fit together so neatly, that there can be little doubt that Darwin was right.