A safer recipe for primordial soup

Feb 03, 2014 by Johnny Bontemps
Stanley Miller performs his famous experiment in issue 1 of "Astrobiology: The story of our search for life in the Universe." Credit: NASA Astrobiology/artwork by Aaron Gronstal.

Researchers have published a simpler, safer method for conducting Miller-Urey origin of life experiments—which may still yield new insight about how life began on Earth.

Back in 1953, Stanley Miller, working at the University of Chicago with Harold Urey, showed how easily one could cook up life's building blocks by simulating the conditions on early Earth.

The famous recipe went as follow:

  • Boil some water to mimic evaporation of the early ocean.
  • Add a few gases thought to be present in the early atmosphere.
  • Apply a jolt of electricity to simulate lightning.
  • Let run for a few days—and you're left with a brownish soup of , the for everything alive on Earth.

But while the success of the Miller-Urey experiment kicked off an entire field of research, Miller had one basic piece of advice for anyone who'd want to try it out: "Don't do it."

"Stanley was always afraid it might lead to a disaster," explains Jeffrey Bada, who was a student of Miller in the 1960s. "If you were not careful to let all the atmospheric air out, the setup could explode. So unless they were highly trained, he'd always advise people against repeating the experiment."

But now a team including scientists from the Georgia Institute of Technology, NASA (including Dr. Bada), and the Tokyo Institute of Technology have recreated a simpler and safer way of conducting Miller-Urey type experiments.

Along with written instructions, the new version was published this month in a step-by-step video format in the Journal of Visualized Experiment.

This video is not supported by your browser at this time.

"In addition to being simpler and safer, the new configuration provides a better representation of Earth's early condition," says Eric Parker, a graduate student at GIT and a lead researcher for the study.

For instance, Miller's original mixture included methane, ammonia, and hydrogen. The new protocol uses nitrogen instead of hydrogen, which we now know is a more accurate representation of the early Earth atmosphere. The likelihood of the experiment exploding is also greatly reduced, since hydrogen is very ignitable in the presence of an electric discharge.

Also, Miller would spark a charge of 60,000 V through the mixture continuously for a week. In the new procedure the charge is set to 30,000 V, and is turned on and off cyclically to mimic the intermittent nature of lightening more accurately.

"There's still a risk since methane is present and also ignitable. But we spell out the inherent risks—and how to avoid them—in clear detail in the new protocol," Parker says.

What's Next?

The researchers hope the new protocol will generate even more interest in the field. "There's still a lot to learn from these experiments," says Bada. "We're barely scratching the surface."

"Some people feel that synthesis of simple compounds has already been done, and so why continue?" he adds. "But I think that's a misrepresentation of the importance of this experiment."

"The next step is figuring out how to go from small molecules (like amino acids) to larger ones (like peptides)—things that have a greater biological functionality," explains Parker. "That's where the next phase of research is kicking in."

What's more, while we know a lot about what's happening in the water phase—where the amino acids are synthesized, we don't know as much about the chemistry going on in the gas phase, explains Bada. "That's an area ripe for research," he says. "From that we can still learn a lot about the chemistry of the early Earth atmosphere, and perhaps even about the atmosphere of other planets."

Explore further: A 21st century adaptation of the Miller-Urey origin of life experiments

More information: See issue 1 of "Astrobiology: The story of our search for life in the Universe" here: www.astrobio.net/index.php?option=com_content&id=7

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User comments : 5

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adam_russell_9615
5 / 5 (1) Feb 03, 2014
But if methane and oxygen were present in the primordial time then maybe explosions are part of the process you are seeking to replicate.
shavera
4.7 / 5 (3) Feb 03, 2014
oxygen was only really added to the atmosphere in significant quantities when photosynthesis began freeing oxygen to exist on its own. Oxygen is too reactive to really have been present in significant amounts back then.
shavera
5 / 5 (2) Feb 03, 2014
Also, I'm really glad to see this happening. I've always wondered why there weren't more repetitions and new results from lab experiments similar to Miller-Urey. And we've come to understand the early Earth environment much better since then as well...
Torbjorn_Larsson_OM
5 / 5 (2) Feb 03, 2014
@shavera: Miller et al did a lot of replications and variations AFAIK, and in later days he himself were interested in ice/water interface chemistry (since it, non-intuitively, does some things faster). But mainly people were elaborating on what they envisioned happened next with soup theories, at lower temperatures and more complex compounds.

Since soup theories now have a lot of (phylogenically and geochemistry motivated) competition from metabolic theories, there's what things happens fastest. E.g. Russell et al vent experiments on protocells, membranes, import chemiosmosis and even nucleotide polymerization since these hot flow reactors are exhibiting thermophoresis & convection. [cf "Thermal trap for DBA Replication", Mast & Braun, Phys Rev Lttrs 2010]
baudrunner
not rated yet Feb 03, 2014
The next step is to apply pressure in a water environment. Earliest bi-lateral nucleated lifeforms, now extinct, massed on the ocean floors. It seems logical that a pressurized environment in an analog of early ocean conditions would force the assembly of amino acids into peptides. Furthermore, Carl Sagan has described the conditions on the moon Titan as being similar to that of a pre-biotic Earth. Tholins would therefore factor into the evolution of that laboratory's product.