2023 Hackaday Prize: The Primordial Soup’s On With This Modified Miller-Urey Experiment

It’s a pretty sure bet that anyone who survived high school biology has heard about the Miller-Urey experiment that supported the hypothesis that the chemistry of life could arise from Earth’s primordial atmosphere. It was literally “lightning in a bottle,” with a mix of gases like methane, ammonia, hydrogen, and water in a closed-loop glass apparatus and a pair of electrodes to provide a spark to simulate lightning lancing across the early prebiotic sky. [Miller] and [Urey] showed that amino acids, the building blocks of protein, could be cooked up under conditions that existed before life began.

Fast forward 70 years, and Miller-Urey is still relevant, perhaps more so as we’ve extended our reach into space and found places with conditions similar to those on early Earth. This modified version of Miller-Urey is a citizen science effort to update the classic experiment to keep up with those observations, plus perhaps just enjoy the fact that it’s possible to whip up the chemistry of life from practically nothing, right in your own garage. Continue reading “2023 Hackaday Prize: The Primordial Soup’s On With This Modified Miller-Urey Experiment”

A Fascinating Plot Twist As Researchers Recreate Classic “Primordial Soup” Experiment

Science is built on reproducibility; if someone else can replicate your results, chances are pretty good that you’re looking at the truth. And there’s no statute of limitations on reproducibility; even experiments from 70 years ago are fair game for a fresh look. A great example is this recent reboot of the 1952 Miller-Urey “primordial soup” experiment which ended up with some fascinating results.

At the heart of the Miller-Urey experiment was a classic chicken-and-the-egg paradox: complex organic molecules like amino acids and nucleic acids are the necessary building blocks of life, but how did they arise on Earth before there was life? To answer that, Stanley Miller, who in 1952 was a graduate student of Harold Urey,  devised an experiment to see if complex molecules could be formed from simpler substances under conditions assumed to have been present early in the planet’s life. Miller assembled a complicated glass apparatus, filled it with water vapor and gasses such as ammonia, hydrogen, and methane, and zapped it with an electric arc to simulate lightning. He found that a rich broth of amino acids accumulated in the reaction vessel; when analyzed, the sludge was found to contain five of the 20 amino acids.

The Miller-Urey experiment has been repeated over and over again with similar results, but a recent reboot took a different tack and looked at how the laboratory apparatus itself may have influenced the results. Joaquin Criado-Reyes and colleagues found that when run in a Teflon flask, the experiment produced far fewer organic compounds. Interestingly, adding chips of borosilicate glass to the Teflon reaction chamber restored the richness of the resulting broth, suggesting that the silicates in the glassware may have played a catalytic role in creating the organic soup. They also hypothesize that the highly alkaline reaction conditions could create microscopic pits in the walls of the glassware, which would serve as reaction centers to speed up the formation of organics.

This is a great example of a finding that seems to knock a hole in a theory but actually ends up supporting it. On the face of it, one could argue that Miller and Urey were wrong since they only produced organics thanks to contamination from their glassware. And it appears to be true that silicates are necessary for the abiotic generation of organic molecules. But if there was one thing that the early Earth was rich in, it was silicates, in the form of clay, silt, sand, rocks, and dust. So this experiment lends support to the abiotic origin of organic molecules on Earth, and perhaps on other rocky worlds as well.

[Featured image credit: Roger Ressmeyer/CORBIS, via Science History Institute]