While much of the history of life on Earth is written, the opening chapters are murky at best. On our ever-changing world, the older a rock is, the more it has changed, obscuring or even erasing evidence of ancient life. Beyond a hazy boundary of circa two billion years, in fact, this interference is so total that no pristine, unaltered Earth rocks are known to exist, making any potential sign of biology as clear as mud.
At least until now. In a study published on November 17 in the Proceedings of the National Academy of Sciences, a group of researchers say they’ve leveraged artificial intelligence to follow life’s trail further back in time than ever before, using machine learning to distinguish the echoes of biology from mere abiotic organic molecules in rocks as old as 3.3 billion years.
The results could more than double how far back in time scientists can convincingly claim to discern molecular signs of life in ancient rocks, the study authors say, citing previous record-setting measurements involving 1.6-billion-year-old rocks.
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