Life on Earth may have originated twice – new study
A new study suggests that life on Earth may have originated twice, independently in bacteria and archaea. Scientists analyzed 420 key chemical reactions and found that LUCA used enzymes for only half of them, while the rest proceeded thanks to natural metals near hydrothermal vents. The authors identify three stages in early life development and argue that bacteria and archaea independently transitioned to a free-living state.
A new study, reported by Popular Mechanics, suggests that life on Earth may have originated twice, independently in bacteria and archaea. Scientists analyzed 420 key chemical reactions responsible for the synthesis of amino acids, vitamins, and RNA bases, and found that the last universal common ancestor (LUCA) used enzymes for only half of these processes, while the other half proceeded thanks to natural metals that were abundant near oceanic hydrothermal vents. Senior author, biologist William Martin, stated: "The new data allow only one conclusion. The lineages of bacteria and archaea independently made the transition to a free-living state. Only free-living cells are alive. Let's call things by their names: we are dealing with one origin of the genetic code, but two origins of life." Co-author, inorganic chemist Harun Tüysüz, explained that natural metals from hydrothermal vents can replace an impressive number of enzymes in metabolic processes. The researchers identified three key stages in early life development: metallic, hybrid, and divergent. According to Martin, the main surprise was that the enzymes used by bacteria and archaea for the same reactions are fundamentally different, proving the independent discovery by nature of ways to control the same chemical processes.