How did life begin on Earth? Munich researchers find important clues

A study by researchers in Munich takes it a step further in answering the question of how life originated on Earth.

In a pioneering experiment in the early 1950s, a scientist attempted to recreate early Earth conditions in a test tube. Stanley Miller put some simple components that he believed were circulating in the young planet's atmosphere and oceans into connected flasks, heated them, and applied electricity to them to simulate lightning. the results It quickly became famous: amino acids, the chemical building blocks of life, came from this primordial soup.

This discovery sparked a search in chemistry and biology for experiments that could help answer one of humanity's greatest scientific questions: How did life begin on Earth? Now scientists at Ludwig Maximilians University in Munich have taken an exciting step forward by showing how more complex molecules essential for life can be manufactured from the building blocks of the early Earth.

In their studies, In the magazine nature published Scientists replaced test tubes with small networks of branching cracks similar to those that form in rocks in nature. They flowed water with key chemical building blocks through the cracks and then used heat to mimic a process that might occur near hydrothermal vents in the ocean or in porous rock near a geothermal pool.

They discovered that heat flowing through these geological networks sorted and filtered molecules, helping them form longer chains called biopolymers, which are essential for life. “This is amazing evidence that simple physical processes can do something like this,” said Matthew Pasek, a professor of geosciences at the University of South Florida, who was not involved in the research.

Because the question of how life arises is so large, it transcends the traditional boundaries that divide science into different disciplines. Chemists, biologists, astrophysicists, and geologists are all at the table trying to answer this question. Going beyond these limits is what Christoph Mast, a biophysicist at Ludwig Maximilian University in Munich, is interested in. His laboratory has designed an experimental setup that comes a little closer to the conditions under which the “biochemistry” from which life arose.

How did the Earth create enough building blocks for life to arise?

For decades, scientists have faced the problem that early Earth was not a pristine laboratory with beakers, perfectly timed purification steps, and a concentrated supply of ingredients. Recreating the chemistry of life in the laboratory is one thing, but the experiments possible in a glass beaker are improbable at best in the chaotic conditions of the real world. “You can imagine the prebiotic soil, this prebiotic soup that's been created that's been very diluted, and all these different things interacting in a way that's completely out of control,” Mast said.

One problem so far is that chemical reactions in the laboratory often produce byproducts that can lead to unwanted reactions, leaving scientists with only trace amounts of the base material. So, how did the early Earth create enough of these building blocks to eventually give rise to life?

To find out, the researchers cut branching networks of interconnecting slits in a small piece of an inert Teflon-like material called FEP and sandwiched it between two sapphire sheets. The rubies were brought to precise but different temperatures to create a flow of heat through the geological network between them, simulating the way heat likely flowed on early Earth – perhaps near volcanoes or hydrothermal vents. They then allowed water and chemicals to flow through the network of cracks and watched what happened.

Amino acids are important, but they are still far from life

In a proof-of-concept experiment, they used glycine, the simplest amino acid, along with a substance called TMP, which can react to join two glycine molecules. Such interactions are difficult in water, and TMP was very rare on early Earth, Mast said. When they simply mixed these ingredients together in a cup or in geological fissures without heat, the amount of more complex biopolymer they produced was “quite small,” the researchers reported.

However, when they introduced a thermal gradient into the cracks, biopolymer production increased dramatically. This is important because amino acids, although important, are far from essential to life. For example, the same basic building blocks are found in lifeless meteorites. “To get to the next level, you have to start making polymers — that's an essential step on the way to the next stage of life,” says Pasek.

The crucial question about how life arose cannot be answered with this setup: Was it in a pool, as it might exist on Earth's surface, or near a hydrothermal vent, as found in the deep ocean? Heat flows through rocks can occur in a variety of geological environments, and were likely “ubiquitous” on the early Earth, Mast says.

The experimental setup can also be used to investigate other questions about early chemistry on the planet. Mast hopes to create a network of cracks in geological materials and build larger networks of interconnected chambers.

“The pot is important for cooking “primal soup.”

This study is another reminder that elegant chemical experiments can ignore an essential part of the primordial soup: the bowl. And in 2021, a team of scientists found that in a famous 1950s experiment, the test tube itself – or rather the borosilicate glass from which it was made – played a role in the results. When the scientists repeated the experiment in a glass beaker, then a Teflon beaker, then a Teflon beaker with a little borosilicate glass, they found that the glass played a crucial role in catalyzing the reactions.

“In other words, to cook the ‘primordial soup,’ the pot is important,” Juan Manuel García Ruiz, a research professor at the Donostia International Physics Center in Spain who participated in the experiment, wrote in an email. He praised the new work for its imaginative approach and, perhaps more importantly, for being “geologically plausible.”

“This may not be the only mechanism, but it is effective, ingenious, and above all it is an experimental demonstration,” García Ruiz said. “I think we need more experimental methods to explore the geochemical context of the planet when life arose.”

We are currently testing machine translations. This article was automatically translated from English to German.

This article was first published in English on April 16, 2024 on “washingtonpost.com” was published as part of the collaboration, and is now also available in translation for readers of the IPPEN.MEDIA portals.