In the 1931 movie “Frankenstein,” Dr. Henry Frankenstein howling his triumph was an electrifying moment in more ways than one. As massive bolts of lightning and energy crackled, Frankenstein’s monster stirred on a laboratory table, its corpse brought to life by the power of electricity.
Electrical energy may also have sparked the beginnings of life on Earth billions of years ago, though with a bit less scenery-chewing than that classic film scene.
Earth is around 4.5 billion years old, and the oldest direct fossil evidence of ancient life — stromatolites, or microscopic organisms preserved in layers known as microbial mats — is about 3.5 billion years old. However, some scientists suspect life originated even earlier, emerging from accumulated organic molecules in primitive bodies of water, a mixture sometimes referred to as primordial soup.
But where did that organic material come from in the first place? Researchers decades ago proposed that lightning caused chemical reactions in ancient Earth’s oceans and spontaneously produced the organic molecules.
Now, new research published March 14 in the journal Science Advances suggests that fizzes of barely visible “microlightning,” generated between charged droplets of water mist, could have been potent enough to cook up amino acids from inorganic material. Amino acids — organic molecules that combine to form proteins — are life’s most basic building blocks and would have been the first step toward the evolution of life.
“It’s recognized that an energetic catalyst was almost certainly required to facilitate some of the reactions on early Earth that led to the origin of life,” said astrobiologist and geobiologist Dr. Amy J. Williams, an associate professor in the department of geosciences at the University of Florida. For animo acids to form, they need nitrogen atoms that can bond with carbon. Freeing up atoms from nitrogen gas requires severing powerful molecular bonds and takes an enormous amount of energy, according to Williams, who was not involved in the research.
“Lightning, or in this case, microlightning, has the energy to break molecular bonds and therefore facilitate the generation of new molecules that are critical to the origin of life on Earth,”
Mist and microlightning
To recreate a scenario that may have produced Earth’s first organic molecules, researchers built upon experiments from 1953 when American chemists Stanley Miller and Harold Urey concocted a gas mixture mimicking the atmosphere of ancient Earth. Miller and Urey combined ammonia (NH3), methane (CH4), hydrogen (H2) and water, enclosed their “atmosphere” inside a glass sphere and jolted it with electricity, producing simple amino acids containing carbon and nitrogen. The Miller-Urey experiment, as it is now known, supported the scientific theory of abiogenesis: that life could emerge from nonliving molecules.
For the new study, scientists revisited the 1953 experiments but directed their attention toward electrical activity on a smaller scale, said senior study author Dr. Richard Zare, the Marguerite Blake Wilbur Professor of Natural Science and professor of chemistry at Stanford University in California. Zare and his colleagues looked at electricity exchange between charged water droplets measuring between 1 micron and 20 microns in diameter. (The width of a human hair is 100 microns.)
“The big droplets are positively charged. The little droplets are negatively charged,” Zare told CNN. “When droplets that have opposite charges are close together, electrons can jump from the negatively charged droplet to the positively charged droplet.”
