Woodpecker

I was stimulated by Chris Packham's programme about 'Snowball Earth'. He describes how, when life was in its very early stages, for much of the 80 million years between 720 million years ago (Ma) and 640Ma all, or almost all, of the planet was encased by ice, shutting down photosynthesis and cutting off most options for life to survive. There are a range of theories (of course) about how it clung on - the one presented by the programme was that single-celled communities persisted in 'dirty puddles', at or near the surface of the ice, where sunlight still penetrated

Several times, the script mentioned the "explosion of life" that took place when the snowball finally melted. A small lightbulb lit in the back of my head with the phrase 'Cambrian explosion' above it - dredged from reluctant studies 50 years ago. Not yet having energy to do anything useful, I looked it up. The Cambrian explosion was the moment (and it geological terms it really was little more than a moment - less than 25 million years) when multicellular life expanded dramatically, and the first animals in almost all of the major taxonomic groups that we recognise today appeared for the first time. If you are looking for a place in history to put the finger of the gods, or the first visit by extraterrestrial intelligence, that was it! 

But I stumbled across something I've never heard of, that the programme also glossed over: the 'Ediacaran period'. This lit no bulbs whatsoever. It was a period that lasted 100 million years, after snowball earth, but before the Cambrian period. In its final 40 million years earth had a sort of dry run for the Cambrian explosion that was to follow. Multi-cellular organisms developed, diverse forms proliferated, evolved, adapted. They got larger and more complex, ecosystems developed. Life, it seemed, was on its way. However, none of these organisms are familiar or similar to anything we see today. For reasons that are unclear, after 40 million years of development, they vanished from the face of the earth, to be replaced by the Cambrian species that are the root of almost everything we see today, 550 million years later

There is something comforting in reading about this stuff. For me it acts as an antidote to politics, immoral corporations, the risk we pose to ourselves, banal daily inhumanity - all the daily noise 

We think of the age of the dinosaurs as a lost world, but the reptiles and birds are still with us (one in the main, 21 in the extra - it's that time of year!). The next time someone says "lost world", my lightbulb is going to illuminate "Ediacaran"