02 March 2017

Oldest fossil evidence for life ever found announced

In the news this week is a truly important scientific finding. (Trump is not truly important). 

Researchers (link below for more info) have eliminated other possible explanations for fossils that reliably date to 3.75 b.y. old. These are microfossils of what are essentially bacteria or bacteria like organisms. What is so significant about this is that it pushes back, right to the actual time when life first became physically possible on this planet, after the period of Solar System history referred to as the Late Heavy Bombardment (when asteroids collided with the inner planets regularly... they're the origin of the giant maria, actually craters, on the Moon). Before that, the surface was regularly literally melted, so that life could not have obtained a foothold. This suggests that either of two broad historical contingencies must have occurred: 1. A spectacularly unlikely event, the origin of life, just happened to occur almost immediately after it first became physically possible. Or, as is at least suggestibly more likely, 2. The origin of life itself is NOT spectacularly unlikely, and, in fact, is likely to occur relatively readily once conditions favorable to it are in place.

As a comment: Indeed, recent investigations have suggested that several other contingencies in the history of life leading to the complex biosphere Earth now has may have been much LESS likely (in that they took a long time to manifest and occurred only once). These would include the evolution of a truly efficient system of photosynthesis and the emergence of eukaryotes, which resulted from the merger of cells belonging to entirely different kingdoms, bacteria and archaea, to form cells with interior organelles that emerged as a whole new form of life, the Eukaryota. (Almost all life visible to naked eye is Eukaryotic).

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