"[Matt] Ridley, author of The Rational Optimist, says the reason life gets better is that ideas have sex.

'Ideas spread through trade,' he told me. 'And when they meet, they can mate, and you can produce combinations of different ideas. I think a good example is a camera pill, which takes a picture of your insides on the way through. It came about (during) a conversation between a gastroenterologist and a guided missile designer ... a process very similar to sex in biology, because through sex, genes meet and recombine, and you get new combinations of genes. That’s what causes innovation in biology, and innovation in culture.'

And life improves."