Re “Evidence of life 3.95 billion years ago found in Canada,” Michael Marshall notes at New Scientist:
His [spokesman Komiya’s] only evidence for the existence of life is the unusual ratio of carbon isotopes, and this may not be definitive. “There are many ways in which abiotic processes can produce such an imbalance, so to conclude that it is evidence for life is simply not justified,” says Sutherland.
Sutherland says a set of chemical reactions known as the Fischer-Tropsch process could be responsible. This process makes organic compounds from hydrogen and carbon monoxide, and show a similar bias towards carbon-12. It is known to occur naturally, for instance in meteorites.
Komiya’s team assumed these reactions were not responsible for their results, on the grounds that there cannot have been hydrogen in Earth’s atmosphere. But Sutherland says there could well have been. If there was water and carbon monoxide in the air, and hot iron from meteorite impacts to act as a catalyst, “hydrogen can easily be generated”. More.
Marshall acknowledges, however, that “Nevertheless, evidence is mounting that life was present earlier than 3.5 billion years ago.” Yes indeed, but don’t wait up for any serious discussion of the consequences for traditional naturalist evolution.
From CBC:
What makes the Labrador rocks particularly special is that they are the oldest known metasedimentary rocks in the world. That is, they were originally formed from sediments deposited by water — the type of environment that decaying organic remains often end up in, said Bell.
The “meta” part of the word indicates that the rocks have been “metamorphosed” or transformed by heat and pressure over time: “They’ve been cooked pretty well,” Bell explains.
That makes them harder to analyze, but not impossible. More.
See also: Tim Standish: Cyanobacteria wouldn’t really work as first life
Rob Sheldon responds to “no life on molten Earth”
But could there really be life at Earth’s molten rock stage?(Tim Standish)
Researchers: Evidence of life 3.95 billion years ago
and
What we know and don’t know about the origin of life