Evidence of Photosynthesis from 4.1 Billion Years Ago
Scientist from two universities based in the California (University of California, Los Angeles and Stanford University) have published a report that proposes that life on Earth may have evolved much earlier than previously thought. The team conclude that life could have existed as far back as 4.1 billion years ago, a remarkable statement as it is believed Earth was formed just a few hundred million years before. Our planet is approximately 4.54 billion years old. To claim that life existed 4.1 billion years ago, puts the origins of life some 300 million years earlier than previously claimed.
Publishing in the on line edition of the journal entitled “Proceedings of the National Academy of Sciences”, the team suggest that graphite identified within ancient zircon crystals found in Western Australia, is evidence of a biological process having taken place. Analysis of the transition of uranium to lead isotopes preserved inside the zircon indicate that the zircon is at least 4.1 billion years old. Therefore the graphite, which must have been older than 4.1 billion years to have become trapped inside, may suggest that biological processes that produced pure carbon were taking place on our planet that far back in deep time.
The Team Identified Dark Spots inside Ancient Zircons
Picture Credit: University of California (Los Angeles)
When Did Life on Earth Begin?
The zircons were formed as a result of volcanism. The Jack Hills region of Western Australia preserves some of the oldest rocks known. Analysis of dark spots found trapped inside the zircon suggests graphite (a form of pure carbon), one that is associated with the process of photosynthesis, a by-product of an ancient biological process.
The co-author of the study, Professor Mark Harrison (University of California, Los Angeles) stated:
“Twenty years ago, this would have been heretical, finding evidence of life 3.8 billion years ago was shocking. Life on Earth may have started almost instantaneously, with the right ingredients life seems to form very quickly.”
This work has implications for understanding how life on our planet started. This research is significant as it suggests that life in the universe may be much more abundant than previously thought.