Yet the earth is still here, unscathed.

There have been mass extinctions associated with some of these events, while other mass extinctions may well have been triggered by subtler internal changes to the biosphere. But none of them seem to have done longterm harm. The first ten million years of the Triassic may have been a little dull by comparison to the late Palaeozoic, what with a large number of the more interesting species being killed in the great mass extinction at the end of the Permian, but there is no evidence that any fundamentally important earth processes did not eventually recover. I strongly suspect that not a single basic biogeochemical innovation — the sorts of thing that underlie photosynthesis and the carbon cycle, the nitrogen cycle, the sulphur cycle and so on — has been lost in the past 4 billion years.