over a billion years The crazy thing is... it was maybe half that maybe even less. The earth is ~4.5 billion years old. There is perhaps-evidence of microbial

over a billion years The crazy thing is... it was maybe half that maybe even less. The earth is ~4.5 billion years old. There is perhaps-evidence of microbial life could be ~4.1 billion years old. More certainly, at ~3.7 billion. The earth is life and life is earth.