Life Arose Rapidly After Heavy Bombardment

Because the early Earth's surface was too hot during the period of heavy bombardment for complex molecular bonds to survive, the clock for life should start around 4 billion years ago, not 4.6; from that point Earth went from organic molecules to self-replicating life within 100 to 200 million years, a stupefyingly fast emergence using native ingredients that leads researchers to conclude we are probably not alone.