Life Twice Over: Earth's Origins May Trace To One Lifeless Forebear

Analysis of chemical reactions in single-celled organisms suggests that life on Earth may have emerged twice. Researchers propose that bacteria and archaea evolved independently from a common non-living precursor rather than descending from a single shared living cell. This hypothesis challenges the traditional theory of a Last Universal Common Ancestor (LUCA) for all existing life forms. Methodology of Evolutionary Reconstruction The study is based on an analysis of metabolic processes in unicellular organisms. Researchers examined internal cellular chemical reactions to trace the evolutionary trajectories of bacteria and archaea, the two largest groups of microorganisms. The method involves identifying common and unique biochemical signatures. The researchers posit that if fundamental cellular mechanisms differ significantly between these groups, it indicates parallel formation rather than a split from a single ancestral living organism.