All life on Earth can trace its origin to LUCA, the last universal common ancestor – and now it seems this organism may have lived a few hundred million years after the planet formed
By Michael Le Page
12 July 2024
An illustration showing how LUCA may have been attacked by viruses
Science Graphic Design
The organism that gave rise to all life present on Earth may have evolved much earlier than once thought, just a few hundred million years after the planet formed, and been more sophisticated than previous assessments have suggested.
The DNA inside all organisms alive today, from E. coli to blue whales, has many similarities, which suggests it can all be traced back billions of years to a last universal common ancestor – LUCA. Many efforts have been made to understand LUCA, but now a study taking a broader approach has turned up some surprising results.
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“What we’ve been trying to do is bring people representative of different disciplines together to come up with a holistic understanding of when LUCA existed and what its biology was,” says Philip Donoghue at the University of Bristol in the UK.
Genes that today are found in all the main branches of life may have been passed down in an unbroken line all the way from LUCA, allowing us to work out what genes the ancient ancestor possessed. By looking at how those genes have changed over time, it should be possible to estimate when LUCA was alive.
In practice, this is much trickier than it sounds, because genes have been lost, gained and swapped between branches. Donoghue says the team has created a complex model that takes account of this to work out which genes were present in LUCA. “We come out with an organism which was much more sophisticated than many people have argued in the past,” he says.