The sale of sex in modern societies is not about spreading genes. Sex has been taken over by the memes.

All other species on this planet are gene machines only. They don't imitate at all well; we alone are gene machines and meme machines as well.

Science has, after all, made some colossal blunders in the past... Our current materialism and its rejection of the idea of a spirit or soul might be just another great falsity.

Finally, we might decide that civilisation itself is worth preserving. In that case we have to work out what to save and which people would be needed in a drastically reduced population - weighing the value of scientists and musicians against that of politicians, for example...

Take male strategies for success in the world. If you've got all the advantages, if you're attractive and clever and all of that, you will generally go for very high quality females.

In proportion to our body mass, our brain is three times as large as that of our nearest relatives. This huge organ is dangerous and painful to give birth to, expensive to build and, in a resting human, uses about 20 per cent of the body's energy even though it is just 2 per cent of the body's weight. There must be some reason for all this evolutionary expense.

You start by copying other people's paintings or music or whatever. You get all of those skills before you branch out. Really creative people have a fantastic ability to copy things and then combine them in new ways. And whether we're talking about genes or memes, recombination is the real heart of creativity.