I'm reading Rare Earth: Why Complex Life is Uncommon in the Universe by Peter D. Ward and Donald Brownlee, which talks about the Cambrian explosion as well, in

I'm reading Rare Earth: Why Complex Life is Uncommon in the Universe by Peter D. Ward and Donald Brownlee, which talks about the Cambrian explosion as well, in the context of the search for extraterrestrial life. It's perhaps a little dated, but a good read.