Sarah Vitak: This is the science of Scientific American’s 60 seconds. I am Sarah Vitak.
The question of how life came to be has captivated humans for millennia. The theory that prevails now is that on a very volatile primitive earth, lightning struck waters rich in minerals. And that the energy of lightning transformed these minerals into the building blocks of life: organic compounds like amino acids. Something we often call the âprimordial soupâ.
The wide acceptance of this theory is largely due to the very famous Miller-Urey experiment. Surely you’ve come across this in a science textbook at some point – but to jog your memory: in 1952, Stanley Miller and Harold Urey simulated the conditions of the early earth by sealing in water, methane, gas, water. ammonia and hydrogen in a glass vial. Then they applied electric sparks to the mixture. Miraculously, amino acids sprang up in the midst of the bubbling mixture. It was a big deal.
But recently, a team of researchers realized that, just like that first primordial soup sitting in a bowl of Earth, the vessel of the experiment played an underestimated role. Perhaps it was also essential to creating organic building blocks inside their Lab Life Soup.
I spoke to someone on the team.
Saladin: I am Raffaele Saladino from the University of Tuscia in Italy.
Vitak: Then, just like today, when a researcher is going to start an experiment, often one of the first things he does is pick up his glassware. Well, today we also use a lot of plastic
Saladin: But 20 years ago in the lab, there were only glass containers because in the mind of the researcher glass is inert.
Vitak: He said inert, which means it doesn’t react with any chemicals you put in it. But in reality this is not necessarily always the case.
Mostly glass is quite inert. When cooking with pyrex (which is made from borosilicate glass, the same type of glass that most lab utensils are made from), the cookware doesn’t go into your brownies. But when you cook, everything in the pot is usually mostly water, so it has a pH of around 7 or so.
But the pH of the Miller-Urey experiment is much higher. In the original experiments, they used a pH of 8.7 which is more alkaline or basic.
Saladin: Why is the alkaline environment an important topic? Since under alkaline conditions the borosilicate can be impacted through the blinds in the reaction menu, it is not inert, it has become a reactant.
Vitak: In fact, this was noted by Miller in his original experiments – that the alkaline conditions caused the silica to dissolve. But he was eclipsed by the discovery of the synthesis of organic compounds. And as future researchers continued, they missed that point in Miller’s notes.
Saladin: Attention was focused on modifying the atmosphere, modifying energy, intensity, and modifying analysis tools.
Vitak: And the role of silica has been completely forgotten.
Dr. Saladino’s team wanted to see if the glass was doing something in the reaction. To test this, they put together three different versions of the original experience where everything was the same except for the containers. For comparison, they chose Teflon which does not dissolve when it has an alkaline solution, like glass does.
Saladin: There is the glass only experiment, the Teflon only experiment, and in the middle there is the Teflon experiment with a few pieces of glass added inside.
Vitak: Then they used a technique called mass spectrometry to analyze what each reaction produced. Mass spectrometry is ideal for determining what types of molecules are found in a complex mixture.
They found that Teflon produced very few organic compounds. There were more compounds in the Teflon with pieces of glass. But the glass container, by far, has created the greatest number and variety of organic molecules.
The exact mechanism of how silica helps catalyze the reaction is not yet clear, but it is very clear.
The obvious question then is: was there silica available in the early earth environment?
Saladin: Water is not suspended in a vacuum. No? Water is in geochemistry, it is surrounded by minerals. Borosilicate and silica are the most abundant minerals that surround water.
Vitak: The team has two major next goals in mind. First, try to update the experiment to more closely model the amount of silica that would have been available at the start of Earth.
Second, they want to try and replace silica with extraterrestrial minerals like pieces of meteorite or rocks from other planets. Besides being very cool, it might give a more concrete idea of ââhow to seek life in space.
But here on Earth, taking one more step to fully understand why we exist is all the more satisfying. Even after nearly 70 years, a key discovery in our complex origin story still bears new revelations. As the authors say in the article: âThe role of rocks was hidden in the walls of the reactors.
Thanks for listening. For 60 Second Science from Scientific American, I’m Sarah Vitak.
[The above text is a transcript of this podcast.]