New study suggests life on Earth began 4.2 billion years ago

A groundbreaking study by an international team of researchers proposes that life on Earth may have started around 4.2 billion years ago, soon after the planet’s formation. Published in Nature Ecology & Evolution, the research focuses on the Last Universal Common Ancestor (LUCA), from which all modern cellular life is believed to have descended. “We did not expect LUCA to be so old,” said Dr. Sandra Alvarez-Carretero from the University of Bristol’s School of Earth Sciences.

Tracing the Genetic History of Life on Earth

The team traced LUCA’s genetic history by comparing genes across various living species and aligning these timelines with fossil records. They concluded that LUCA existed around 4.2 billion years ago. “Our results fit with modern views on the habitability of early Earth,” Alvarez-Carretero stated. The study also discovered that genetic fingerprints of LUCA are still present in a wide range of species, including those seemingly unrelated.

Modeling LUCA’s Biology

Researchers examined the physiological properties of modern species to model LUCA’s biology. Lead author Dr. Edmund Moody explained that their exchange between lineages complicates the evolutionary history of genes, requiring complex models to reconcile gene history with species genealogy. The study revealed that LUCA was a complex organism similar to modern prokaryotes and had an early immune system, indicating an ancient battle with viruses.

The research suggests that LUCA was not just a passive organism but actively exploited and changed its environment. Co-author Tim Lenton from the University of Exeter noted that this indicates the existence of an early recycling ecosystem, where LUCA’s waste served as food for other microbes. This finding provides further insight into the complex interactions and dependencies within ancient ecosystems on Earth.

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