According to new researches, life as we know it didn't start 2.7 billion years ago, as first speculated. The process that is fundamental to sustaining life on this planet actually started developing some 2.15 billion years ago, argue researchers at the California Institute of Technology in Pasadena, following a thorough analysis of fossilized plants and oil deposits.
 

Photosynthesis is the main oxygen generating process on Earth. It allows plants and trees to directly convert carbon dioxide and water into essential byproducts, such as carbohydrates and oxygen. The latter is released back into the atmosphere. This ability vegetation has was mainly responsible for "the great oxidation" event, which occurred some 2.4 billion years ago. At that time, the proportions of gases in Earth's atmosphere changed sufficiently enough to give simple unicellular organisms the chance to grow and develop.
 

Previous studies, dating back as far as a decade ago, uncovered several traces of oxygen-consuming organisms in 2.7 billion-year-old deposits, which led scientists conducting them to believe that they had found the exact period when our planet started producing massive amounts of oxygen. The late Archaean period is now under scrutiny, as the new survey sheds some doubt over what many people thought happened at that time.
 

Birger Rasmussen at the Curtin University of Technology in Perth, Australia, leader of the latest study, said that, in fact, the discoveries made by other scientists some years ago were flawed because the traces the other guys found were newer than 2.7 billion years. According to Rasmussen, those molecules were simply contaminants in the fossilized oil deposit. The two were not formed at the same time, showed a new device, called a NanoSIMS ion probe, which determines the types of carbon isotopes in such deposits.
 

Western Australia's Pilbara region was home to these new finds. "The oil had to have formed in the rock, but its isotopic signature was completely different to that of the microbial fossils, so we concluded that the microbial fossils were more recent contaminants. We suspect that those studies [done a decade ago] will turn out to be flawed, too," concluded Rasmussen.