New research out of Stanford University adds a “striking” new twist to an existing theory about how life may have began on our planet, involving the occurrence of microlightning in tiny water droplets.
Known as the Miller-Urey hypothesis, the theory stems from a classic 1952 experiment that demonstrated how life’s building blocks could form when electricity similar to lightning interacts with a mix of water and gases. Now, Stanford scientists believe nature’s sparks may have been much smaller, occurring in tiny water droplets from waterfalls and ocean waves.
In the recently released study from Stanford, researchers showed that when water is sprayed into a mix of gases like Earth’s early atmosphere, it can create important building blocks of life like uracil, a key component of DNA and RNA.
“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,” said senior author Richard Zare, the Marguerite Blake Wilbur Professor of Natural Science and professor of chemistry in Stanford’s School of Humanities and Sciences.
Scientists theorize that after Earth’s formation, a swirl of chemicals surrounded the planet, but initially lacked life’s essential building blocks. The Miller-Urey experiment offered one possible explanation: lightning striking the ocean and interacting with early atmospheric gases—such as methane, ammonia, and hydrogen—could generate organic molecules. However, critics argue that lightning is too infrequent and the ocean too vast for this to be a likely mechanism.
Researchers found that when water droplets are divided by spray or splash, they develop different electrical charges. Larger droplets become positively charged, while smaller ones are negatively charged. Sparks, or “micro lightning,” occur between droplets with opposite charges.
“Little droplets bud off (split from) bigger droplets. Electrons are lighter than positively charged ions, Electrons preferentially jump on to the smaller droplets making them negatively charged. The bigger droplet, which starts off as neutral, becomes increasingly positively charged as little droplets leave the bigger droplets,” says Zare in an email to The Debrief.
“The separation of positive and negative charges is what causes an electric field to develop. When the strength of the electric field becomes sufficiently large, you get electrical breakdown in the gas separating two droplets of opposite charge,” Zare explained. “This electrical breakdown produces a spark as electrons jump from the negatively charged water droplet to the positively charged water droplet. I call this spark microlightning.”
“There is enough energy in the spark to dissociate, excite, and ionize the surrounding gas molecules, which leads to chemical reactions,” Zare said.
High-speed cameras captured the flashes, which are too small for the human eye to detect. Despite their size, these flashes carried energy. Researchers demonstrated this by spraying water into a gas mixture believed to resemble early Earth’s atmosphere. The team suggests that microlightning from crashing waves or waterfalls may have sparked the earliest stages of life—not just lightning strikes from the sky.
“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,” Zare said. “I think this overcomes many of the problems people have with the Miller-Urey hypothesis.”
Zare’s research team focuses on investigating the potential power of small bits of water, including how water vapor may help produce ammonia, a key ingredient in fertilizer, and how water droplets spontaneously produce 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,” he said.
Zare told The Debrief that microlightning also has the potential to revolutionize modern chemistry, with implications for industrial applications and green energy production.
“We are using water microdroplet sprays to make fertilizers, such as ammonia, urea, and nitrate,” Zare said. “This is done at room temperature without applying any external voltage or external radiation. The nitrogen in the fertilizer comes from air and the hydrogen from water. The challenge is whether this process can be scaled up economically,” says Zare.
Looking beyond Earth, could similar conditions exist on other planets? Could this process work under simulated extraterrestrial environments—such as on Mars, Titan, or Europa—where water and atmospheric gases also interact?
“To make this process happen, we need liquid water that is sprayed into droplets,” Zare said. “Thus, I expect that the small building block of life, that is, small molecules containing carbon-nitrogen bonds, can be found elsewhere than just on Earth. Of course, small building blocks are not the full solution to making life from nonlife.”
“These building blocks need to combine with one another in a process we call polymerization to form larger building blocks, and we propose that wet-dry cycles promote polymerization,” Zare added.
“Many more experiments need to be done to better understand how all this might happen,” he concluded.
Chrissy Newton is a PR professional and founder of VOCAB Communications. She currently appears on The Discovery Channel and Max and hosts the Rebelliously Curious podcast, which can be found on The Debrief’s YouTube Channel on all audio podcast streaming platforms. Follow her on X: @ChrissyNewton and at chrissynewton.com.