If you go to the octopus, and if you're not too squeamish, dissect it. You'll find that it has a camera eye which is remarkable similar to our own. And yet we know that the octopus belongs to an invertebrate group called cephalopod mulluses, evolutionarily very distant indeed from the chordates to which we belong.

The tree of life was always there. Evolution just fills in the gaps.

The Burgess Shale is not unique, but for those who study evolution and fossils it has become something of an icon. It provides a reference point and a benchmark, a point of common discussion and an issue of universal scientific interest.

By obtaining a sense of its place in the unfolding drama of life, set in an ecological theatre, so we can understand why it has become one of the leading players.

If there were a clear prospect that such evils were part of a barbarian past, then at least we might find a small crumb of comfort. No such prospect exists: no scientific analysis can even remotely answer or account for past and present horrors of human behaviour.

Evolution is true, it happens, it is the way the world is, and we too are one of its products. This does not mean that evolution does not have metaphysical implications; I remain convinced that this is the case.