Science Advances Study Says Life Began Twice After 420-Reaction Ancestor Split

3 articles · Updated · spacedaily.com · Aug 14

A 7 August Science Advances paper argues bacteria and archaea became free-living cells independently after diverging from LUCA, reframing “life began twice” as two separate completions of metabolism rather than two origins from scratch.
401 archaeal and 552 bacterial genomes, mapped across a roughly 420-reaction metabolic network, led researchers to place only about half the enzymes in LUCA and infer the rest were initially supplied by environmental chemistry.
Five core reactions are central to the claim: bacteria and archaea use structurally unrelated enzymes for the same jobs, which the authors interpret as convergent evolution after the two lineages split.
Native iron, cobalt, nickel and palladium in serpentinising hydrothermal systems could have catalysed missing reactions, and the study reports phosphite can help form energy-rich phosphate bonds in water under such metal-catalysed conditions.
The model challenges fuller LUCA reconstructions, including a 2024 study proposing a 2.75 million-base, 2,657-protein ancestor, and remains contested pending more archaeal genomes, protein structures and lab tests.