As a tease for the soon-coming Bjork Meets Attenborough programme, they've released a bit of the pair's chat where David explains why pop is about sex*:
When asked by Bjork how music works in the modern day, Sir David said: “Well, one is absolutely clear, and that is the sexuality.* - This claim, explicitly, takes no account of the Johnny Borrell solo album
“And as it were classical times, troubadours singing up to their lady loves up on the balcony come and join me or let me come in.
“But in our own culture now, I mean pop music is hugely sexual, there can’t be any doubt about that. And that is why it is so popular amongst people between 15 and 30. That’s the peak of sexuality and it’s the peak of the passion about music.”