Düsseldorf study suggests life arose twice in bacteria and archaea

A study in Science Advances proposes that bacteria and archaea independently acquired free-living metabolism, suggesting life may have originated twice rather than once. Researchers led by William Martin analyzed enzyme structures in genomes. The last common ancestor lacked enzymes for half its metabolic reactions, relying on hydrothermal metals; after splitting, bacteria and archaea evolved distinct solutions. The study also found phosphite with palladium can perform phosphorylation without ATP, supporting protocell viability. If confirmed, the tree of life may have two roots, raising questions about life's possible origins elsewhere.