The organism that scientists refer to as the “last universal common ancestor of the universe” lived 4.2 billion years ago.
According to Sci-News, a group of scientists from the University of Bristol (UK) has successfully sought out the “last universal common ancestor” (LUCA), a hypothetical ancestor of all life on Earth and possibly many other planets.
LUCA is at the top of the Earth’s ecological hierarchy, from which early life forms, including bacteria and archaea, diverged.
A strange germ of life, more complex than we thought, arrived on Earth and became the common ancestor of all species? – (Image AI: ANH THƯ).
As widely accepted theories about the origin of life on Earth suggest, after our planet formed, the first life forms “traveled” from space via meteors and comets.
Over billions of years, these life forms evolved into the entire biological world we see today.
What did that first life form look like? Was it a single organism or merely primitive prebiotic materials? LUCA may very well be that life form.
In the recent study, scientist Edmund Moody from the University of Bristol and colleagues compared all the genes in the genomes of living species, counting the mutations that occurred in their sequences over time.
The divergence time of certain species is known from the fossil record, allowing researchers to use a genetic equation similar to familiar physical equations to calculate the time LUCA existed.
The results indicate that LUCA lived approximately 4.2 billion years ago, about 400 million years after Earth formed.
Dr. Sandra Álvarez-Carretero, a co-author, stated they did not expect this common ancestor to be so ancient.
However, this result aligns with modern views on the habitability of early Earth.
Previously, it was believed that until the end of the Hadean eon around 3.8 billion years ago, Earth was not a fiery sphere and that life only began to emerge afterward.
However, some recent evidence from Australia shows signs of organic material likely originating from microorganisms, “sealed” in rocks aged 3.8 to 4.1 billion years.
The research process by the Bristol team also indicates that LUCA was a complex organism, not too different from modern prokaryotes, but what is truly interesting is that it clearly possessed an early immune system.
LUCA exploited and modified its habitat but was unable to live in isolation. It depended on the very organisms that evolved from it. Its waste would also serve as food for other bacteria, helping to create a recycling ecosystem.
According to Professor Philip Donoghue, a co-author, LUCA illustrates how quickly ecosystems could form on early Earth.
This also suggests that life could thrive in Earth-like biospheres elsewhere in the vast universe.
The study was recently published in the scientific journal Nature Ecology & Evolution.
