FYI -- Possible evidence that life may not have started on Earth, after all... http://www.nytimes.com/2016/07/26/science/last-universal-ancestor.html Meet Luca, the Ancestor of All Living Things "This venerable ancestor was a single-cell, bacterium-like organism. But it has a grand name, or at least an acronym. It is known as Luca, the Last Universal Common Ancestor, and is estimated to have lived some four billion years ago, when Earth was a mere 560 million years old." "Life could have originated anywhere and later been confined to a deep sea environment because of some catastrophic event like the Late Heavy Bombardment, which occurred 4 billion to 3.8 billion years ago. This was a rain of meteorites that crashed into Earth with such force that the oceans were boiled off into an incandescent mist. ... Life is so complex it seems to need many millions of years to evolve. Yet evidence for the earliest life dates to 3.8 billion years ago, as if it emerged almost the minute the bombardment ceased." (Perhaps Luca arrived *with* the Late Heavy Bombardment?)