Oxygen ‘Oases’ Led to All Life on Earth

2396165921_06c6657f18 Two and a half billion years ago the atmosphere contained almost no oxygen, Arizona State University scientists say, and life as we know it was not possible in an environment devoid of oxygen. The presence of oxygen in Earth's atmosphere came from ancient microbes inhabiting "oxygen oases" in the oceans billions of years ago, when microbes known as cyanobacteria appeared that could capture sunlight to create energy through photosynthesis, and in the process altered Earth's atmosphere by the production of oxygen, a waste product to cyanobacteria but essential for later life.

"Our research shows that oxygen accumulation on Earth first began to occur in surface ocean regions near the continents where the nutrient supply would have been the highest," Brian Kendall, a research associate at ASU's School of Earth and Space Exploration, said. "The evidence suggests that oxygen production in the oceans was vigorous in some locations at least 100 million years before it accumulated in the atmosphere."

Although focused on Earth's atmosphere, its findings could have relevance for the search for microbial life on other planets. "One of the ways we will look for life on planets orbiting other stars is to look for oxygen in their atmospheres," Professor Ariel Anbar, director of the Astrobiology Program at ASU, said. "So we want to know how the rise of oxygen relates to the emergence of photosynthesis."

Casey Kazan via Arizona State University.


"The Galaxy" in Your Inbox, Free, Daily