When Could Life Have Appeared on Earth? Scientists' Answer

Scientists have proposed a hypothesis that bacteria and archaea may have independently developed complex cellular mechanisms despite a shared genetic code. A study that reconstructed about 420 metabolic reactions showed different origins for some enzymes in the two groups. The authors suggest that the common ancestor LUCA did not have a fully independent metabolism and depended on metals in hydrothermal vents. The model remains a hypothesis requiring verification.

Researchers have proposed a new hypothesis about the origin of life on Earth, according to which bacteria and archaea may have independently developed complex cellular mechanisms despite a shared ancient genetic code. This implies two separate paths to cellular organization, but not two separate instances of life arising from non-living matter. The scientists reconstructed about 420 metabolic reactions and compared the genomes of bacteria and archaea, finding that some enzymes responsible for the same processes have different origins. This indicates that after the split of the common ancestor LUCA, the two lineages independently developed their own enzyme systems. Likely, LUCA did not yet have a fully independent metabolism and relied on environmental metals, especially in hydrothermal vent areas. Over time, both lineages replaced this external support with their own enzymes. One of the authors, William Martin, explained: "We are dealing with one origin of the genetic code, but two origins of life." The authors emphasize that their findings do not indicate two independent cases of abiogenesis, but rather separate evolution toward autonomy. The model remains a hypothesis and requires further verification. If confirmed, the view of life's formation would change: the common foundation might not be a ancestral cell, but an ancient genetic system.

When Could Life Have Appeared on Earth? Scientists' Answer