Scientists have revisited a famous experiment that explored how life may have begun on Earth, uncovering a new potential pathway, CNN reports.
Their research suggests that tiny, nearly invisible bursts of “microlightning” occurring within water droplets could have played a crucial role in forming the building blocks of life.
In 1953, chemists Stanley Miller and Harold Urey conducted an experiment simulating early Earth’s atmosphere. They combined gases like ammonia, methane, and hydrogen inside a sealed glass sphere and zapped it with electricity. The result? The formation of amino acids—essential components of proteins, which are fundamental to life. This experiment supported the theory of abiogenesis: the idea that life arose from nonliving chemical compounds.
Now, scientists have taken this idea a step further. Instead of large electrical discharges, they investigated the role of small-scale electrical interactions within misty water droplets. Their findings, published in Science Advances on March 14, suggest that these tiny sparks of energy could have generated the same amino acids found in the original Miller-Urey experiment.
The new study, led by Dr. Richard Zare of Stanford University, explored how electrical charges form and interact within microscopic water droplets. When water mist forms, the larger droplets tend to carry a positive charge while the smaller ones carry a negative charge. When these oppositely charged droplets come close together, electrons jump between them, producing flashes of microlightning.
To test this concept, researchers recreated early Earth’s atmospheric conditions by mixing ammonia, methane, carbon dioxide, and nitrogen in a glass bulb. They then sprayed the gases with water mist and observed tiny flashes of electrical discharge. When they analyzed the contents, they discovered amino acids and other organic molecules—just like in the Miller-Urey experiment.
“We discovered no new chemistry; we have actually reproduced all the chemistry that Miller and Urey did in 1953,” Zare explained. “But what we have done, for the first time, is observed that tiny water droplets can emit light and generate sparks that drive these chemical transformations.”
While traditional lightning has long been considered a possible catalyst for life’s formation, some scientists have questioned whether it occurred frequently enough to produce amino acids in the necessary quantities. Microlightning, on the other hand, could have been much more common.
Since mist and water spray were abundant on early Earth, these tiny electrical discharges might have continuously sparked chemical reactions in pools and puddles. Over time, this could have led to the formation of increasingly complex molecules, eventually resulting in the emergence of life.
While this study presents a new perspective on how life’s building blocks may have formed, the origins of life remain a mystery. Other competing theories suggest that life’s first molecules may have been formed around deep-sea hydrothermal vents or even arrived from space via comets or meteorites.
Dr. Amy J. Williams, an astrobiologist at the University of Florida who was not involved in the study, noted that while the findings don’t provide a definitive answer, they contribute valuable insight.
“This study provides another avenue for the formation of molecules crucial to the origin of life,” she said.
