Andrew Marr explores how Darwin's theory of evolution by natural selection has taken on a life of its own far beyond the world of science.

In the first episode of the three-part series, Andrew Marr explores how Darwin's theory of evolution by natural selection has taken on a life of its own far beyond the world of science.

He argues that Darwin's theory has transformed our understanding of what it means to be human. Over the last 150 years, Darwin's ideas have challenged the need for a creator, undermined religious authority, and provided new ways of looking at the origins of human morality.

Marr's journey begins following Darwin's footsteps in Tierra del Fuego at the southernmost tip of South America where Darwin first encountered an 'uncivilised' native tribe. This began to raise questions in his mind about the origins of the human race. The answers to these questions would emerge over the next 30 years, culminating in the publication of On The Origin of Species in 1859.

Marr then traces the development of Darwin's idea in the years since then and finds a range of influences that Darwin could never have imagined: from the existential philosophy of Friedrich Nietzsche to the battlefields of the First World War; from the Freudian psychoanalyst's couch to the Vatican; and from the genetic logic of kindness to an Islamic creationist's claim that Darwin is to blame for modern terrorism. Darwin's dangerous idea is as influential and challenging today as it was 150 years ago.