Study suggests Earth’s first cells arose twice from separate lineages
Researchers say the earliest free-living bacteria and archaea likely originated independently, pointing to two distinct births of life on Earth.
Scientists from the Institute of Molecular Evolution at Heinrich-Heine University Düsseldorf reported evidence that free-living bacteria and archaea each made the transition to independent cellular life in separate events. By reconstructing a 420-reaction metabolic network and tracing enzyme origins, they discovered that the last universal common ancestor possessed enzymes for only half of these reactions, the rest being driven by environmental metals.
Subsequent evolutionary paths saw bacteria and archaea independently invent distinct enzymes for the same essential reactions, reducing reliance on vent chemistry. The team also identified palladium-catalyzed phosphorylation of phosphite as a plausible pre-ATP energy source. Their findings, published in Science Advances, suggest a single genetic code but two origins of cellular life.
Why it matters
Understanding whether life began once or twice reshapes theories about early evolution and the conditions needed for life elsewhere.
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