Dr Thomas Dixon presents a timely history of the changing meaning and experience of friendship over the centuries.

Charles Darwin loved his dog and praised her in letters to friends as "the beloved and beautiful Polly". He believed that dogs shared qualities such as a sense of shame, honour and affection with humans, and wrote about them in The Expression of the Emotions in Man and Animals.

It was in this era that dogs were, for the first time, given the title of "man's best friend".

Thomas Dixon traces the impact of Darwin's own relationship with animals on his theory of evolution, and compares it with his ideas about other, "savage" human beings, whom he encountered in Tierra Del Fuego, during his trip on the Beagle.

He also considers Darwin's deeply affectionate and intimate friendship with his fellow-scientist, Joseph Hooker, at a time when it is often believed men were disinclined towards displays of emotion.

With contributions from Emma Townshend, author of Darwin's Dogs, and Hooker expert Dr Jim Endersby.

Producer: Beaty Rubens

First broadcast on BBC Radio 4 in April 2014. Show less