Earliest Evidence of Oxygen Producers Is Found in 2.5-Billion-Year-Old Rock

Australian scientists have unearthed the earliest direct evidence of when the world’s microorganisms began to produce oxygen, shedding more light on the mystery surrounding the start of life as we know it. Roger Summons and colleagues at the Australian Geological Survey Organization in Canberra report in today’s Nature that they found “molecular fossils” in 2.5-billion-year-old sedimentary rocks from the Mount McRae shale in western Australia. Molecular fossils are organic compounds derived from living organisms and found in sedimentary rock. The team found 2-methylhopane, an unmistakable molecular fossil of cyanobacteria.

--Compiled by Times medical writer Thomas H. Maugh II