Life’s Building Blocks May Have Formed in the Cracks of Volcanoes

The flowing of molten rocks through small cracks in the heart of volcanoes may have been a perfect environment to forge the building blocks of life on Earth.

Heat flows moving through cracks in volcanic rocks can result in the purification of molecules from complex mixtures of materials, which may have resulted in the creation of specific chemicals needed for life to evolve, according to a new paper in the journal Nature.

These chemicals—called biopolymers—are an essential building block for the origins of life, and until now, their formation was something of a mystery to scientists.

Previously, it had been hard to replicate the conditions of ancient Earth in order to test how these biopolymers could have been made, due to the amount of other by-products also generated at the same time and the difficulty in filtering them out. However, in this new study, the authors explain how they used specially built chambers with tiny cracks to isolate and purify these molecules, mimicking the cracks that would have existed in ancient rocks.

They describe how they created chambers inspired by geological magma chambers, each with tiny cracks measuring only 170 micrometers across. These cracks enabled them to separate out over 50 molecules that are considered among the most important to prebiotic life, ranging from amino acids to nucleotides.

“Here we show that heat flows through thin, crack-like geo-compartments could have provided a widely available yet selective mechanism that separates more than 50 prebiotically relevant building blocks from complex mixtures of amino acids, nucleobases, nucleotides, polyphosphates and 2-aminoazoles,” the authors wrote in the paper.

“Using measured thermophoretic properties, we numerically model and experimentally prove the advantageous effects of geological networks of interconnected cracks that purify the previously mixed compounds, boosting their concentration ratios by up to three orders of magnitude.”

They also found that this filtration system was powered by a temperature gradient through the cracks, with even a minor temperature difference on either side allowing for certain molecules like 2-aminozoles and amino acids to increase in concentration by a factor of 10 and three orders of magnitude, respectively.

These concentrations could be further increased by making the crack network bigger. Additionally, these cracks were found to aid in the reaction of two glycine molecules—as a result of increased concentrations of the molecule—which is one of the major starting points for the synthesis of peptides, required for the existence of proteins.

“The universal availability of heat fluxes on the early Earth, either from the geological setting or as a waste product of one of many exothermic reactions, makes this mechanism conceivable in various environments,” they wrote.

As cracks like these were likely very common on the early Earth, the researchers suggest that they may have played a major role in the origins of life’s building block chemicals.

“Systems of interconnected thin fractures and cracks or comparable permeable pathways are thought to be ubiquitous in volcanic and geothermal environments. Connected to the surface, such systems can potentially feed spatially separated ponds or pools, whose role in the origin of life has been extensively studied,” they wrote.

“Given the wide availability of heat flows and fractures in rocks, the observed applicability to even small prebiotic compounds and the overall robustness of the process, thermophoretic enrichment of organics could have provided a steady driving force for a natural origins-of-life laboratory,” the researchers said.

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