How did life begin on Earth? It's one of science's greatest mysteries. Today, researchers at the UK's MRC Laboratory of Molecular Biology published findings in the journal Science that bring us closer than ever to an answer.

They've discovered QT45 — a tiny RNA molecule that can copy both itself and its complementary strand. This is the first time scientists have found an RNA molecule small enough to have appeared spontaneously in Earth's primordial soup, yet capable of self-replication.

🧬 Why This Changes Everything

For decades, one leading theory has suggested that RNA molecules spontaneously formed billions of years ago and began replicating and evolving — eventually giving rise to all life on Earth.

The problem? Scientists had previously only found RNA strands capable of copying other RNA. These molecules were far too long and complex to have appeared by chance. They couldn't copy themselves.

"Everyone in this field had been working on the same ribozyme lineage for over 30 years," said lead author Edoardo Gianni, "and believed that finding a new one would be very difficult, and that it had to be a long RNA sequence to carry out its function."

QT45 shatters that assumption.

🔬 Small But Mighty

Copying RNA is a complicated process involving a cascade of sophisticated molecular interactions. Scientists assumed only large, complex RNA molecules could manage it.

QT45 proved them wrong.

Its remarkably small size means two revolutionary things:

1. It's much easier for QT45 to copy itself than larger molecules
2. It could plausibly have appeared spontaneously in Earth's early oceans

"By identifying a small RNA, it makes the whole idea that self-replicating RNA emerged spontaneously much more likely," Gianni explained. "And thanks to its size, it managed to copy all of itself and its template — unlike previous work where only small parts were copied."

⚗️ How They Found It

The MRC team's breakthrough came through a clever experimental approach:

• Generated vast pools of random RNA sequences
• Selected those with RNA-copying activity
• Ran repeated rounds of laboratory evolution
• QT45 emerged as a highly efficient ribozyme

Researchers confirmed QT45's ability to copy diverse RNA sequences and, critically, to synthesize itself and its complementary strand — the two key reactions needed for self-replication.

🪐 Are We Alone?

The discovery has profound implications beyond Earth.

"Beyond its scientific significance, the discovery also has implications with regards to how likely life is to emerge spontaneously and whether similar processes could occur on other planets," Gianni said.

If a small, self-replicating RNA molecule like QT45 can appear spontaneously from simple chemicals, the conditions needed for life's emergence may be more common in the universe than previously thought.

🧪 What's Next

The team has now successfully demonstrated experimentally the two key reactions needed for self-replication:

1. Copying the template strand
2. Copying itself

Their next goal? Combining these two reactions to kickstart a complete self-replication cycle — essentially creating synthetic life in a test tube.

If they succeed, it would be the first time scientists have recreated the spark of life from scratch.

💡 A Piece of the Puzzle

Dr. Glenn Wells, Deputy Executive Chair at the Medical Research Council (MRC), captured the significance:

"I think we should take a moment to appreciate how weird and wonderful our jobs are, when our colleagues may have discovered a piece of the puzzle of how life began on earth!"

"This remarkable breakthrough showcases how our MRC LMB researchers are continually resetting the boundaries, merging physics, chemistry and biology to understand the building blocks of life."

🌍 From Primordial Soup to You

Think about it: Every living thing on Earth — from bacteria to blue whales, from mushrooms to humans — may trace its ancestry back to a moment 3.5 billion years ago when a tiny RNA molecule, not unlike QT45, started copying itself in a warm ocean pool.

That first self-replicating molecule made mistakes. Those mistakes became mutations. Mutations became evolution. Evolution became life in all its staggering diversity.

And today, scientists in Cambridge have found a molecule that shows us how it all might have begun.

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