None of us would be around if the organisms hadn’t been provoked billions of years ago. The question of fair how this spark appeared still fascinating scientists.
New research into how primordial Earth conditions could have produced life has identified a mixture of salts that, mixed with the heat flows from the molten rock, could have contributed to the formation of self-replicating biomolecules.
This self-replication is a key part of the “RNA world” hypothesis: the idea that ribonucleic acids (RNA) can store biological information and perform the folding of the structure necessary for life to grow and evolve toward current status.
In this case, the scientists examined the mixture of magnesium (Mg) and sodium (Na) as it might have been on Earth in its early years: for RNA folding to work, a relatively high concentration of ions doubly charged magnesium and a lower concentration of individually charged sodium is required.
“Consequently, the question arises of which early Earth environments could have provided suitable salt conditions for these prebiotic processes. A geologically likely process that produces saline environments is the leaching of salts from basalt,” the team writes. international group of researchers in their study. .
“As the primary partial melting of the Earth’s mantle, basalt is one of the most abundant rock types that can be expected in the Earth’s initial crust, as well as the crust of other terrestrial planets in our solar system.”
The team synthesized basaltic glass, which occurs naturally on Earth when molten basalt cools rapidly (by contact with ocean water, for example), and characterized it in its various forms, including the rock and the glass.
An analysis of the amount of magnesium and sodium extracted from the glass, under various temperatures and with a wide variety of grains, always showed significantly more sodium than magnesium.
In addition, magnesium levels were always significantly lower than necessary for prebiotic RNA folding to function properly. The researchers found that the missing part of the process was convective heat fluxes.
“This situation changed considerably when heat currents were added – which are likely to be present, due to the high levels of geological activity expected in prebiotic environments -” says biophysicist Christof Mast of Ludwig Maximilians University. Munich to Germany.
“We have shown that a combination of basaltic rocks and simple convection currents can lead to the optimal ratio between Mg and Na ions under natural conditions.”
The temperature gradients that appear in the cracks and narrow pores of the basalt glass create the convective fluxes needed for salt optimization and also move more ions against the current, creating what is known as thermophoresis.
Together, convection and thermophoresis increase the number of magnesium ions in the mixture, creating conditions where self-replicating RNA can be produced, according to the study. The same type of chemical reactions may have occurred on Earth 4 billion years ago.
This leaching of basalt salts, which is found in abundance in the Earth’s mantle, adapts to the template for the RNA world hypothesis to work, according to research. In addition, it expands the possibilities in terms of salt mixtures that may have helped bring about life.
“The principle demonstrated here is applicable to a wide range of salt concentrations and compositions and, as such, is highly relevant to various life-origin scenarios,” the researchers write in their published article.
The research has been published in Nature chemistry.