CAMBRIDGE, Mass. -- Today, oxygen takes up a hefty portion of Earth's atmosphere: Life-sustaining O2 molecules make up 21 percent of the air we breathe. However, very early in Earth's history, O2 was a rare if not completely absent player in the turbulent mix of primordial gases. It wasn't until the "Great Oxidation Event" (GOE), nearly 2.3 billion years ago, when oxygen made any measurable dent in the atmosphere, stimulating the evolution of air-breathing organisms and, ultimately, complex life as we know it today.
Now, new research from MIT suggests O2 may have been made on Earth hundreds of millions of years before its debut in the atmosphere, keeping a low profile in "oxygen oases" in the oceans. The MIT researchers found evidence that tiny aerobic organisms may have evolved to survive on extremely low levels of the gas in these undersea oases.
In laboratory experiments, former MIT graduate student Jacob Waldbauer, working with Professor of Geobiology Roger Summons and Dianne Newman, formerly of MIT's Department of Biology and now at the California Institute of Technology, found that yeast an organism that can survive with or without oxygen is able to produce key oxygen-dependent compounds, even with only miniscule puffs of the gas.
The findings suggest that early ancestors of yeast could have been similarly resourceful, working with whatever small amounts of O2 may have been circulating in the oceans before the gas was detectable in the atmosphere. The team published its findings last week in the Proceedings of the National Academy of Sciences.
"The time at which oxygen became an integral factor in cellular metabolism was a pivotal point in Earth history," Summons says. "The fact that you could have oxygen-dependent biosynthesis very early on in the Earth's history has significant implications."
The group's results may help reconcile a debate within the earth sciences community: About a decade ago, ge
|Contact: Caroline McCall|
Massachusetts Institute of Technology