Origin-of-Life Study Points to Chemical Chimeras, Not RNA

Image credit: NAUTILUS

Origin-of-life researchers have usually studied the potential of pure starting materials, but messy chemical composites may kick-start life more effectively.

Jordana Cepelewicz | NAUTILUS

Scientists studying how life arose from the primordial soup have been too eager to clean up the clutter.

Four billion years ago, the prebiotic Earth was a messy place, a chaotic mélange of diverse starting materials. Even so, certain key molecules still somehow managed to emerge from that chemical mayhem—RNA, DNA and proteins among them. But in the quest to understand how that happened, according to Ramanarayanan Krishnamurthy, a chemist at the Scripps Research Institute in California, researchers have been so myopic in their focus on reactions that generate molecules relevant to the planet’s current inhabitants that they’ve overlooked other possibilities.

“They are trying to impose biology today on prebiotic chemistry,” he said. “But trying to make the final product right from the raw material—it misleads us.”

“We forget the mixture,” he added—and with it, the more circuitous chemical routes that could have potentially led to the same biological outcome, the intermediate stages on the path to life that have since faded without a trace.

It makes sense that experimentalists preferred to keep things clean and direct—to synthesize important compounds like amino acids or nucleotides in bits and pieces, and to think of life as bubbling out of more pristine beginnings. “The feeling was that if you tried to incorporate too much into your system,” said John Sutherland, a chemist at the MRC Laboratory of Molecular Biology in England, “everything would start to degrade and you’d just get a mess.”

But research is beginning to show that starting with the right kind of mess is not only more realistic, but more effective at generating the materials vital to life, while also doing away with problems that have plagued purer systems. “There are times when we have mixtures, rather than just the isolated reactants that people typically use, and we get better results,” said Nicholas Hud, a chemist at the Georgia Institute of Technology. When mixtures are taken into consideration, the emergence of life on Earth in some ways “is not as hard as we might think it is.”

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