An article published in the journal “Proceedings of the Royal Society B: Biological Sciences” reports the results of a study on the origin of oxygenic photosynthesis. A team of researchers developed a new gene analysis technique to estimate the origin of cyanobacteria capable of oxygenic photosynthesis. The conclusion is that all the species of these cyanobacteria existing today have a common ancestor that dates back to about 2.9 billion years ago and that the ancestors of cyanobacteria branched off from other bacteria about 3.4 billion years ago. Oxygenic photosynthesis probably evolved during that time interval.