14 DAY TRIAL // About 2.3 billion years ago, vast amounts of molecular oxygen (O2) made their way into Earth's atmosphere, during an time known as the Great Oxygenation Event (GOE). New data suggest that the molecules existed before that time, trapped in oceanic “oxygen oases.”
At this time, the gas makes up for more than 21 percent of the entire atmosphere, but things weren't always so. Before 2.3 billion years ago, the air was extremely toxic, filled with nitrogen, sulfur, carbon dioxide and other harmful gases.
When GOE occurred, oxygen changed the characteristics of our planet's atmosphere, enabling early life to start developing at high speed. Experts widely agree that the event was largely responsible for the development of complex life on our planet.
In the new study, researchers at the Massachusetts Institute of Technology (MIT), in Cambridge, found that molecular oxygen in fact existed before GOE, but that it kept what the team refers to as a low profile, hiding in oxygenated oases inside the planet's sprawling oceans.
Tiny aerobic organisms that the scientists studied showed signs that they adapted to surviving in very low concentrations of oxygen. Microorganisms such as yeast were found to be able to produce key oxygen-dependent compounds even in minute O2 concentrations.
Former MIT graduate student Jacob Waldbauer, geobiology professor Roger Summons and former MIT Department of Biology expert Dianne Newman – now at Caltech – conducted the lab experiments that revealed the connection.
What this implies is that yeast's ancestors were capable of the same performances millions of years before GOE occurred. Details of the new study appear in the latest issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS).
“The time at which oxygen became an integral factor in cellular metabolism was a pivotal point in Earth history. The fact that you could have oxygen-dependent biosynthesis very early on in the Earth's history has significant implications,” Summons explains.
What the team concluded from available data is that oxygen existed in very low concentrations inside Earth's oceans some 300 million years ahead of the Great Oxygenation Event. The scarcity of the element could explain why no records of this were kept in the geological record.