Life on Earth might not have started with a dramatic lightning strike, but rather through thousands of microlightning exchanges among water droplets. Stanford University researchers discovered this reaction forms vital organic molecules, challenging long-held theories about life’s inception.
The origins of life on Earth may trace back not to a grand lightning strike into the primordial ocean but to countless tiny bolts of “microlightning” occurring within water droplets from crashing waves or waterfalls, new research from Stanford University suggests.
Published in the journal Science Advances, the study demonstrates that these microelectric discharges can produce organic molecules with carbon-nitrogen bonds, including uracil — a fundamental component of DNA and RNA. This revelation adds depth to the Miller-Urey hypothesis, which has long postulated that life’s building blocks were created by lightning strikes.
“Microelectric discharges between oppositely charged water microdroplets make all the organic molecules observed previously in the Miller-Urey experiment, and we propose that this is a new mechanism for the prebiotic synthesis of molecules that constitute the building blocks of life,” senior author Richard Zare, the Marguerite Blake Wilbur Professor of Natural Science and professor of chemistry in Stanford’s School of Humanities and Sciences, said in a news release.
For over 2 billion years after Earth’s formation, the planet had a mixture of chemicals but lacked organic molecules with carbon-nitrogen bonds, essential for proteins, enzymes and other biological compounds.
The Miller-Urey experiment offered one explanation for how these molecules formed, suggesting that lightning striking the ocean interacted with atmospheric gases like methane, ammonia and hydrogen. However, critics argue that lightning was too sporadic and the ocean too vast for this solution to be practical.
The Stanford team — including postdoctoral scholars Yifan Meng and Yu Xia, and graduate student Jinheng Xu — proposes an alternative.
They investigated how water droplets develop different charges when dispersed through sprays or splashes. Larger droplets often carry positive charges, while smaller ones carry negative. When these oppositely charged droplets collide, they create sparks or “microlightning.”
Using high-speed cameras, the researchers captured these tiny yet potent flashes of light. They demonstrated the energy produced by spraying room-temperature water into a gas mixture reminiscent of early Earth’s atmosphere. This mixture included nitrogen, methane, carbon dioxide and ammonia, and the results confirmed the formation of organic molecules like hydrogen cyanide, the amino acid glycine and uracil.
“On early Earth, there were water sprays all over the place — into crevices or against rocks, and they can accumulate and create this chemical reaction,” added Zare. “I think this overcomes many of the problems people have with the Miller-Urey hypothesis.”
Beyond this groundbreaking discovery, Zare’s team is also examining the potential of water microdroplets in other chemical reactions, such as the production of ammonia and hydrogen peroxide.
“We usually think of water as so benign, but when it’s divided in the form of little droplets, water is highly reactive,” Zare added.
This study received support from the Air Force Office of Scientific Research and the National Natural Science Foundation of China.
Source: Stanford University