Origin of life on earth, part two

Yesterday we asked when and how life on earth began. We didn't answer that question. We offered a scenario for a proto-life, but also noted that much more would have to happen for that to become cellular life as we generally understand the term.

It is possible that life -- considered as something DISTINCT from the proto-life I discussed yesterday, had two origins. There were two paths forward, so to speak, bacteria and archaea. The bacteria developed first. Muh later, the archaea developed and absorbed the bacteria so the later became the energy producing part (the mitochondria) of larger cells.

As to the timing? The best guess sets the early RNA replication (proto-life) at about 4 billion years ago. There were complicated cells, leaving a fossil record, by 3.5 billion years ago, so each of the two paths described above had been executed by then.

IF any of this is right. Science proceeds by falsification, and this all may be falsified as new evidence arises. But I think it is encouraging that serious scientists are working on this problem. It may help us in the search for exobiology. If it is right, this hypothesis tells us where to look for life on other planets-- look for planets with deep oceans and possible thermal activity down below.

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