Spark of evolution found in ancient African soil
The Earth was formed 4.6 billion years ago and, until now, scientists believed that oxygen began accumulating in the planet's atmosphere about 2.3 billion years ago. (Image: NASA)
Thursday, September 26, 2013, 8:01 AM -
A new study is rewriting the history of the very origins of life on Earth.
Sean Crowe, an assistant professor in Earth, Ocean and Atmospheric Sciences at the University of British Columbia, and researchers from the University of Copenhagen's Nordic Centre for Earth Evolution, looked at three-billion-year-old soil from South Africa -- the oldest soil left in the world today.
The Earth was formed 4.6 billion years ago and, until now, scientists believed that oxygen began accumulating in the planet's atmosphere about 2.3 billion years ago.
Using advanced technology, Crowe and the other scientists studied the chemical composition of the soil and used mathematical models to determine that trace amounts of oxygen began to appear three billion years ago -- 700 million years earlier than believed.
Crowe, the co-lead author of the study, was not available for an interview Wednesday but said in a statement that this event permanently altered the planet.
"This evolutionary event forever changed the composition of the atmosphere, supported the expansion of aerobic life, and charted a course for the ultimate evolution of animals including humans,'' said Crowe, who is currently in Indonesia.
That formative event is referred to by scientists as the Great Oxygenation Event. The oxygenation of Earth -- the spark for evolution -- is believed to be owed to cyanobacteria, microbes that consume carbon dioxide and release oxygen, or photosynthesize.
Oxygen built up in the atmosphere, and today is comprised of 20 per cent oxygen.
Lasse Dossing, the other lead author of the study published Wednesday in the journal Nature, said advances in technology that allowed them to explore the planet's geological history are "truly remarkable.''
"Technology similar to that used in our study, could provide a powerful tool to search for oxygen and signs of life on planets such as Mars,'' Dossing said.
