Reuters  
Sydney
An ancient zircon crystal unearthed in Western Australia may hold evidence that life appeared on the planet 4.1 billion years ago, or about 300 million years earlier than previously thought, according to a team of U.S. researchers.
Scientists from Stanford University and the University of California, Los Angeles said they recently collected some 10,000 multibillion year-old zircons in Jack Hills, Australia, including one believed to contain a carbon deposit that is 4.1 billion years old, give or take 10 million years.
“Its complete encasement in crack-free, undisturbed zircon demonstrates that it is not contamination from more recent geologic processes ... (and) may be evidence for the origin of life on Earth by 4.1 (billion years ago),” according to a paper published by the team in the Proceedings of the National Academy of Sciences on Monday.
Scientists have used the fossil record to assert that the history of life on Earth began about 3.8 billion years ago, in the form of single-celled creatures. Humans are believed to have first appeared on Earth only about 200,000 years ago. The study was authored by Elizabeth Bell, Patrick Boehnke, and T. Mark Harrison of the University of California, Los Angeles along with Wendy Lao of Stanford.