User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-5460283-20130921175439/@comment-5043481-20130924160127

Early in it's life earth was a scorched lava covered rock, with an atmosphere made of mostly carbon dioxide, with no oxygen. For a billion years nothing alive grew on the surface. It was only until 580 million years ago that complex animals arrived. This is the earliest time we have fossils from animals.

My point is that life took about 3 billion years from the creation of the planet for it to start getting interesting. Complex life when the planet is forming? I dought it.