[LINK] "The Paleo Recipe for Complex Life on Earth"

[rfmcdonald]

At The Dragon's Tales, Will Baird has a thought-provoking essay noting the evidence that complex life might have first evolved on Earth in Paleoproterozoic era, more than two billion years before the present and one billion years before commonly thought.

The Earth is racked by global glaciations. Ones which have been called the Snowball Earth. They stretch over the entire planet from the poles through the equator. There is some dispute whether or not the oceans were completely frozen over (a slushball earth vs snowball), but the glaciations are acknowledged as real.

The monstrous glaciation is understood to have been triggered by a sudden drop in the atmospheric carbon dioxide levels. This, in turn, is believed to have been caused by photosynthetic organisms drawing down the CO2 levels while spiking the oxygen levels (relatively speaking). Yes, the snowball earth events are, like in the Eocene's Azolla Event, examples of biogenic climate change.

Within 100 million years of the end of the Snowball Earth complex life arose. Except it would vanish from the fossil record, probably having gone extinct and changing the biological fate of the Earth.

Wait. You thought I was talking about the Cryogenian and Ediacaran?

After all, the Cryogenian's Marinoan Glaciation (or maybe Sturtian or Kaigas), NeoProterozoic Oxygenation Event, Ediacaran with its biota and then Cambrian do parallel all of the above. Except that complex life is obviously still around and the Phanerozoic is quite biologically diverse, to say the least.