Did life on Earth only arise once? Perhaps not

A recent study published in Science Advances suggests that life on Earth may have arisen twice rather than once. According to the research, the last common ancestor of all living organisms, referred to as LUCA, was not fully alive but instead depended on metals from hydrothermal vents for its metabolism. This challenges the conventional belief that LUCA was a complex cell with a primitive immune system.

The study, conducted by William Martin at Heinrich Heine University in Düsseldorf, employed a metabolic lens to analyze the genes required to convert early earth elements into the essential components of cells, such as amino acids, nucleotide bases, and cofactors. The findings indicate that bacteria and archaea, the first two branches of the tree of life, independently developed the ability to create their own enzymes for essential chemical reactions.

This led to the possibility that LUCA was a cluster of RNA, DNA, and enzymes within a hydrothermal vent, relying on metals to produce amino acids. The researchers found that palladium can catalyze a crucial reaction, converting phosphite to phosphate, which releases energy that could have powered LUCA. While modern life's last common ancestor is not the same as the origin of life, the study highlights the potential role of geochemistry in facilitating the transition from chemistry to biology.

Further experiments are necessary to test these theories and deepen our understanding of the nature of LUCA and the role of bacteria and archaea in the evolution of life.