Virtually all oxygen on Earth was and is produced by photosynthesis, which was invented by tiny organisms, the cyanobacteria, when our planet was still a rather uninhabitable place.
Cyanobacteria evolved more than 2.4 billion years ago, but Earth only slowly transformed to the oxygen-rich planet we know today.
“We do not fully understand why it took so long and what factors controlled Earth’s oxygenation,“ said geomicrobiologist Judith Klatt. “But when studying mats of cyanobacteria in the Middle Island Sinkhole in Lake Huron in Michigan, which live under conditions resembling early Earth, I had an idea.” [Read more…] about A long day for microbes, and the rise of oxygen on Earth