One of the things that is often said about the frankly catastrophic loss of biodiversity in the world today is that extinction is a natural process of the living world, and this is quite true. Extinction does not naturally occur at a constant rate, however. It ranges from near instantaneous (as when a 12-km-wide rock hits the planet, causing a Very Bad Day for most living things) to a slow background rate of extinction of species that have been reduced to a relic of past distributions and population numbers. So, when those who do not think we are in a catastrophic situation say, ‘Extinction is natural’, point out to them that the present scale of extinction is in global terms worse than a 12-km bolide, at least in geological terms, for the geological record doesn’t distinguish easily between a one-day catastrophe and a four-century one. Both are ‘sudden’ events in Deep Time. As E. O. Wilson wrote, in his book The Diversity of Life (1992)