Life on Earth as we know it may have had an earlier start than previously thought. New research indicates that oxygen, a key component in the formation of complex organisms, was present in the Earth's atmosphere 700 million years before previous estimates.
"We've always known that oxygen production by photosynthesis led to the eventual oxygenation of the atmosphere and the evolution of aerobic life," says Sean Crowe, an assistant professor in at the University of British Columbia.
"This study now suggests that the process began very early in Earth's history, supporting a much greater antiquity for oxygen producing photosynthesis and aerobic life."
Most scientists chalk up the arrival of significant amounts of atmospheric oxygen to an event 2.3 billion years ago known as the "Great Oxygenation Event." It was during this time that the Earth underwent a period of great oxygen accumulation, leading to the 20-percent-oxygen-infused atmosphere we have today.
Researchers looking at 3-billion-year-old soil samples from South Africa, however, found trace amounts of atmospheric oxygen, indicating the Earth's oxygenation process had already started. Oxygen began seeping into the Earth's atmosphere thanks to early photosynthetic bacteria that take carbon dioxide and turn it into oxygen. The larger and larger amounts of oxygen allowed for more complex organisms than bacteria, such as ourselves, to form.
"These findings imply that it took a very long time for geological and biological processes to conspire and produce the oxygen rich atmosphere we now enjoy," says Lasse Døssing, the other lead scientist on the study, from the University of Copenhagen.
You can read the full published study detailing the findings in the journal Nature.