Our planet is estimated to be 4.5 billion years old. Life on Earth might have appeared an estimated 3.83 billion years ago. However, groundbreaking research pinpoints the start of life at 4.1 billion years ago.
The staggering difference was revealed after analysis of just one fragment of zircon-trapped graphite, the purest form of carbon. In 2008 another research suggested a similar hypothesis, according to which life on Earth has evolved fairly rapidly after the formation of the planet, only 440 million years after the event.
However, it was proven that the samples under analysis had been contaminated and the results were dismissed. Nonetheless, the 2008 research opened the door to a number of questions relating to the origin of life on our home planet and the time of its emergence.
For the new groundbreaking research, scientists with the University of California at Los Angeles collected over 10,000 zircons from nowadays western Australia. Originating in the molten rock of the region, zircons are durable minerals that often preserve pieces of material surrounding them as they formed.
Geophysicists have often turned to zircons to find clues of life. From the over 10,000 zircons, only 656 were suitable for further analysis as they showed some dark spots under the microscope.
Of them, only two were found fit for the research. And only one zircon was the final choice, as the second was found to have fine cracks. The graphite encapsulated in the zircon was the basis of the research. Carbon isotopes found in ancient graphite reveals clues on the origins of life. This groundbreaking research pinpoints the start of life at 4.1 billion years ago.
After thorough analysis, the geophysicists found that the graphite in the zircon presented a high ratio of carbon-12 to carbon-12. It is this ratio that suggests that the biological origin of the carbon found in the zircon is around 4.1 billion years old.
The study is published in the Proceedings of the National Academy of Sciences journal.
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