But how is half a billion years a “precise estimate”?:
Now, MIT scientists have a precise estimate for when cyanobacteria, and oxygenic photosynthesis, first originated. Their results were published on September 29, 2021, in the Proceedings of the Royal Society B.
They developed a new gene-analyzing technique that shows that all the species of cyanobacteria living today can be traced back to a common ancestor that evolved around 2.9 billion years ago. They also found that the ancestors of cyanobacteria branched off from other bacteria around 3.4 billion years ago, with oxygenic photosynthesis likely evolving during the intervening half-billion years, during the Archean Eon.
Jennifer Chu, Massachusetts Institute of Technology, “MIT Scientists Zero In on the Origins of Earth’s “Single Most Important Evolutionary Innovation”” at SciTechDaily (September 30, 2021)
One maven points out that the only thing the researchers actually did was estimate the assumed timing of the origin of photosynthesis via molecular clock techniques.
The really remarkable thing is that, if they are right, photosynthesis, despite its complexity, began in the first billion years that there was any kind of life.
Botanist Margaret Helder writes to comment “The point to reflect on is what all those heterotrophs did for food prior to the appearance of the autotrophs. Any organic molecules in the environment would be quickly digested if there were only organisms around with no capacity to reduce carbon.”
Hmmm. Were some of them metabolizing compounds and elements directly?
The paper is open access.