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.

Certainly almost everything we do and think is colored in some way by memes, but it is important to realize that not everything we experience is a meme. If I walk down the street and see a tree, the basic perception that's going on is not memetic.

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...

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

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.

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.

For the planet's sake, I hope we have bird flu or some other thing that will reduce the population, because otherwise we're doomed.