Episode 2 of The Nerve asks the question why? Why did music evolve in the first place? Some people think music is merely an evolutionary frill, a by-product - delicious cheesecake for our ears that has no evolutionary purpose. Darwin himself was puzzled by music. Observing songbirds, he suggested music's role was in sexual selection (which may explain why rock stars from Franz Liszt to Tommy Lee have had such busy sex lives). Others believe music's origins may be found in the mother-infant interactions we call baby talk, and others consider the importance of the lullaby - a need to pacify infants. Others theorize that music developed in tandem with the social cohesion necessary to the survival of bands of early humans, critical to them through its power to strengthen social bonds.

Cheesecake? Or sex, baby talk, and social interaction? Set in the Key of DNA, The Nerve 2 examines what the purpose of music is and has been, yesterday and today.