Thus the creationist's favourite question "What is the use of half an eye?" Actually, this is a lightweight question, a doddle to answer. Half an eye is just 1 per cent better than 49 per cent of an eye.

I doubt that religion can survive deep understanding. The shallows are its natural habitat. Cranks and fundamentalists are too often victimised as scapegoats for religion in general. It is only quite recently that Christianity reinvented itself in non-fundamentalist guise, and Islam has yet to do so.

Five per cent vision is better than no vision at all. Five per cent hearing is better than no hearing at all. Five per cent flight efficiency is better than no flight at all. It is thoroughly believable that every organ or apparatus that we actually see is the product of a smooth trajectory through animal space, a trajectory in which every intermediate stage assisted survival and reproduction.

The genetic code is not a binary code as in computers, nor an eight-level code as in some telephone systems, but a quaternary code with four symbols. The machine code of the genes is uncannily computerlike.

But, however many ways there may be of being alive, it is certain that there are vastly more ways of being dead, or rather not alive.

The replicators that exist tend to be the ones that are good at manipulating the world to their own advantage. But other replicators are also successful otherwise they would not be common. The world therefore tends to become populated by mutually compatible sets of successful replicators, replicators that get on well together

DNA is ROM. It can be read millions of times over, but only written to once - when it is first assembled the birth of the cell in which it resides.