Life on earth was flourishing within a few hundred million years of the planet being formed, new research has revealed.
A research team led by the University of Bristol said all of today’s life derived from a single common ancestor known as LUCA (Last Universal Common Ancestor).
“LUCA is the hypothesised common ancestor from which all modern cellular life, from single celled organisms like bacteria to the gigantic redwood trees (as well as us humans) descend,” the study report said.
“LUCA represents the root of the tree of life before it splits into the groups, recognised today – bacteria, archaea and ekarya.”
The team compared all the genes in the genomes of living species, counting the mutations that have occurred within their sequences “over time since they shared an ancestor in LUCA”.
The data was then used to calculate when LUCA existed. The answer was 4.2 billion years ago, about four hundred million years after the formation of Earth and our solar system.
Co-author Dr Sandra Álvarez-Carretero of Bristol’s School of Earth Sciences said the team had not expected LUCA to have existed so soon after the Earth’s formation but the findings were consistent with contemporary views on the habitability of early Earth.
The study also revealed that early life already possessed an immune system and was “engaging in an arms race with viruses”.
Co-author Tim Lenton (University of Exeter, School of Geography) said it was clear that LUCA was exploiting and changing its environment, but it is unlikely to have lived alone.
“Its waste would have been food for other microbes, like methanogens, that would have helped to create a recycling ecosystem,” he said.
Another co-author Professor Philip Donoghue said the research pulled together data from multiple disciplines to achieve results that could not be achieved alone.
“It (the study) demonstrates just how quickly an ecosystem was established on early Earth,” he said. “This suggests that life may be flourishing on Earth-like biospheres elsewhere in the universe.”
The full report is on the University of Bristol website.
