World’s oldest rocks show signs of life on Earth 3.2 billion years ago

3.2 billion year old sedimentary rock samples from Australia contain chemical evidence for nitrogen fixation by microbes.

Recent findings from Earth and Space Sciences‘ Roger Buick, Eva Stüeken, and Matt Koehler, with Bradley Guy from the University of Johannesburg, suggest that life on Earth may have flourished more than a billion years earlier than previously thought. Nitrogen is a building block of amino and nucleic acids, both essential for life on Earth. By studying some of the planet’s oldest rocks, which contain preserved chemical clues and are free of chemical irregularities, the team concluded that life was pulling nitrogen out of the air and converting it into a form that could support larger communities 3.2 billion years ago.