Researchers at the Massachusetts Institute of Technology, or MIT, discovered that oxygen may have been laying low in undersea "oxygen oases" before making contact with the atmosphere.
The researchers said this was long before the Great Oxidation Event, or GOE, as they have found evidence that small aerobic organisms may have evolved to survive on extremely low levels of oxygen in undersea oases.
Jacob Waldbauer, a former MIT graduate student, conducted laboratory experiments along with Professor of Geobiology Roger Summons and Dianne Newman, on yeast, which can survive with or without oxygen.
The scientists found that even with a little bit of oxygen, yeast is able to produce key oxygen-dependent compounds, and therefore, indicated that early ancestors of yeast could've worked tiny amounts of oxygen that may have been in the oceans before it was detectable in the atmosphere.
"The time at which oxygen became an integral factor in cellular metabolism was a pivotal point in Earth history," Summons said in a press release. "The fact that you could have oxygen-dependent biosynthesis very early on in the Earth's history has significant implications."
The finding is published in the Proceedings of the National Academy of Sciences.