New scientific study rearranges hypotheses about the origin of life on Earth

A recent international study has reignited debate on one of science's oldest questions: how did life begin on Earth? The findings suggest that the two primary branches of the tree of life, bacteria and archaea, may have independently transitioned to a free-living state after diverging from a common ancestor approximately four billion years ago.

Published in "Science Advances," the study was led by researchers from Heinrich Heine University Düsseldorf in Germany. It concludes that the last universal common ancestor of all living organisms, known as LUCA, was likely not a fully functional independent cell as we understand them today. Instead, LUCA was probably bound to the environment of deep-ocean hydrothermal vents, where minerals and gases facilitated its essential chemical processes for survival.

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The new data leads to the conclusion that the bacterial and archaeal lineages independently transitioned to a free-living state.

Archaea are single-celled microorganisms that resemble bacteria but differ in their chemical composition and genetic mechanisms, leading scientists to classify them as a distinct group. Some archaea are known for thriving in extreme environments like highly saline waters, hot springs, and the deep ocean.

The study clarifies that life did not originate twice independently from non-living matter. Rather, it proposes that the genetic code traces back to a single origin, but the transition to independent cellular life occurred twice, once for the lineage leading to bacteria and once for the lineage leading to archaea. William Martin, a lead researcher, stated that the new data suggests these two lineages independently adopted a free-living existence, indicating "one origin for the genetic code, but two origins for life" if life is defined by a cell's ability to become independent of its environment.

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one origin for the genetic code, but two origins for life