From at ScienceDaily:
Ancient microbes may have been producing oxygen through photosynthesis a billion years earlier than we thought, which means oxygen was available for living organisms very close to the origin of life on earth. In a new article in Heliyon, a researcher from Imperial College London studied the molecular machines responsible for photosynthesis and found the process may have evolved as long as 3.6 billion years ago.
One surprising finding was that the evolution of the photosystem was not linear. Photosystems are known to evolve very slowly — they have done so since cyanobacteria appeared at least 2.4 billion years ago. But when Dr. Cardona used that slow rate of evolution to calculate the origin of photosynthesis, he came up with a date that was older than the earth itself. This means the photosystem must have evolved much faster at the beginning — something recent research suggests was due to the planet being hotter.
“There is still a lot we don’t know about why life is the way it is and how most biological process originated,” said Dr. Cardona. “Sometimes our best educated guesses don’t even come close to representing what really happened so long ago.” Paper. (public access) – Tanai Cardona. Early Archean origin of heterodimeric Photosystem I. Heliyon, 2018; 4 (3): e00548 DOI: 10.1016/j.heliyon.2018.e00548 More.
See also: Researchers: Plants colonized Earth 100 mya earlier than thought
Hat tip: Philip Cunningham