Once upon a time, the Earth was a barren wasteland. But all that changed when something began to move from the chemicals that were present early in Earth’s history and began to process the available materials to survive, reproduce, and thrive.
What that something was, and when it first stirred, has been a burning question that has haunted humanity perhaps ever since we were able to ask, “What am I?”
Now, new research provides some answers, revealing that life emerged surprisingly quickly.
By studying the genomes of currently living organisms, scientists have determined that the Last Universal Common Ancestor (LUCA), the first organism that gave rise to all life on Earth today, emerged as early as 4.2 billion years ago.
For comparison, the Earth is about 4.5 billion years old, meaning life first emerged when the planet was still in its infancy.
“We did not expect LUCA to be so old, within just a few hundred million years of Earth’s formation.” “It’s a very interesting story,” says evolutionary biologist Sandra Alvarez Carretero. “However, our findings are consistent with modern views of the habitability of the early Earth,” say researchers from the University of Bristol in the UK.
When the Earth was first created, it was a very different place than it is today, and the atmosphere is very toxic. The amount of oxygen needed for life today is Relatively late in the Earth’s evolutionary historyIt began about 3 billion years ago.
But life began before that, and we Microbial fossils from 3.48 billion years agoAnd scientists think that the environment on Earth may have been stable enough to support life. About 4.3 billion years ago.
However, our planet has been subject to erosive, geological and organic processes that make it nearly impossible to find evidence of life at that time.
So a team of scientists, led by systematist Edmund Moody of the University of Bristol, started looking elsewhere: into the genomes of living organisms and the fossil record.
Their work is based on something called a molecular clock: essentially, by estimating the rate at which mutations occur and counting them, they can determine how much time has passed since the organisms in question diverged from a common ancestor.
All living things, from the tiniest microorganisms The strongest fungusAll living organisms have a few things in common: They have a universal genetic code. They make proteins in the same way, with 20 nearly universal amino acids that all point in the same direction. And all living organisms use adenosine triphosphate (ATP). As an energy source within cells.
Based on these similarities and differences, Moody and his colleagues were able to calculate how long it had been since LUCA’s successors began to diverge. Then, using complex evolutionary models, they were able to learn more about LUCA itself, what it was, and how it managed to survive on an Earth that was so inhospitable to its descendants.
According to their research, LUCA is probably ProkaryotesIt is a single-celled organism that does not have a nucleus. Oxygen independentThis is not unexpected for microbes, since there was very little oxygen, so their metabolic processes Probably produced acetic acid.
But there was something else interesting: it seems LUCA wasn’t alone.
“Our study shows that LUCA is a complex organism not very different from modern prokaryotes.” “We’re not sure what the genome is made of,” says phylogenetic scientist Davide Pisani. From the University of Bristol.
“But what’s really interesting is that it’s clear that humans had an early immune system, and that by 4.2 billion years ago our ancestors virus“
Its metabolic processes produced waste products that other life forms could use, so it is possible that it emerged not long after LUCA.
This means that it would take a relatively short time in the planet’s evolutionary history for a complete ecosystem to emerge — a discovery that has implications far beyond our own small history. Pale blue dot.
“Our research integrates data and methods from multiple disciplines to reveal insights about the early Earth and life that could not be achieved by any single discipline alone.” Paleontologist Philip Donoghue explains. From the University of Bristol.
“It also shows how quickly ecosystems were established on the early Earth, suggesting that life could thrive in an Earth-like biosphere somewhere in the universe.”
This study Natural Ecology and Evolution.
