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

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.

Just as the design of our bodies can be understood only in terms of natural selection, so the design of our minds can be understood only in terms of memetic selection.

Imagine a world full of brains, and far more memes than can possibly find homes. Which memes are more likely to find a safe home and get passed on again?

If everyone understood evolution, then the tyranny of religious memes would be weakened, and we little humans might find a better way to live in this pointless universe.

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.

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...