A new study adds another angle to the much-disputed Miller-Urey hypothesis, which argues that life on the planet emerged from a lightning strike. The analysis says that water sprays are sufficient for generating organic compounds, without requiring electricity from external sources
How life began on Earth has been a long-standing mystery, but according to a study the process could have been kicked off simply with crashing waterfalls and breaking waves that would have thrown up mists of water.
The findings add another angle to the much-disputed Miller-Urey hypothesis, which argues that life on the planet emerged from a lightning strike. They were described in the study, ‘Spraying of water microdroplets forms luminescence and causes chemical reactions in surrounding gas’, which was published in the journal Science Advances last week.
What is the Miller-Urey hypothesis?
The Earth formed around 4.6 billion years ago. For a few billion years afterwards, it had a rich mixture of chemicals but almost no organic molecules with carbon-nitrogen bonds. These bonds are crucial for proteins, enzymes, nucleic acids, chlorophyll, and other compounds that makeup living beings today.
In 1952, American chemist Stanley Miller and physicist Harold Urey performed an experiment in which they successfully demonstrated that the organic compounds (such as amino acids) needed for life could form with the application of electricity to a mixture of water and inorganic gases. Put simply, the two scientists showed that a lightning bolt struck the ocean, triggering chemical interaction with gases such as methane, ammonia, and hydrogen that created organic molecules.
The experiment was considered a landmark at the time as it gave one of the possible explanations for how life could have found its first foothold on Earth. However, in the following years, many scientists raised doubts about the experiment, saying “real lightning would have struck infrequently — and mostly in open ocean, where organic compounds would have quickly dispersed,” according to a report by Scientific American.
And what did the new study find?
According to the new study, water spray is sufficient to generate organic compounds without the requirement of external electricity. Stanford University chemist Richard Zare, who led the analysis, told Scientific American, “Unlike lightning… water sprays are everywhere”. Zare and his team showed that when water droplets divide, they develop opposing charges. While larger droplets have positive charges, smaller ones carry negative ones. When these oppositely charged droplets move close together, tiny sparks leap between them. This process, called “microlightning” by the researchers, imitates how lightning forms in clouds. As a result, when Zare and his team sprayed water into a mixture of nitrogen, methane, carbon dioxide and ammonia, it led to the formation of organic compounds, including hydrogen cyanide, glycine, and uracil. According to the researchers, the findings showed that it was not necessarily that lightning strikes may have kick-started life on Earth. Tiny sparks due to crashing waves or waterfalls may have done the job. “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… I think this overcomes many of the problems people have with the Miller-Urey hypothesis,” said Zare in a statement.
Source: Indian Express, 18/03/25
