According to science, none of us would have existed on Earth if the first organisms had not been brought back to life billions of years ago. The question of how it came about has fascinated scientists to this day.
New research examining ancient Earth conditions has identified a mixture of salts that fused with heat flows from molten rock. This unique blend has the potential to contribute to the formation of self-replicating biomolecules.
This self-replication is an important part of the 'RNA world' hypothesis, namely the idea that ribonucleic acid (RNA) can store biological information and carry out the folding of structures necessary for life to grow and develop into the state it is today.
In this case, as quoted from Science Alert, scientists see a mixture of magnesium (Mg) and sodium (Na) as may have happened on Earth in the early years of its appearance, triggering RNA folding to work. In addition, a relatively high concentration of double-charged magnesium ion and a lower concentration of single-charged sodium ions are required.
"Therefore, the question arises as to which early Earth environment might have provided suitable saline conditions for such a prebiotic process. One of the processes that may geologically produce saline environments is the leaching of salt from basalt," the researchers wrote in their study report.
"As a major part of the melting of Earth's mantle, basalt is one of the most abundant rock types present in the Earth's early crust, as well as the crust of other terrestrial planets in our Solar System," the researchers said.
The team of scientists synthesized basaltic glass that naturally occurs on Earth when molten basalt is rapidly cooled (through contact with seawater, for example), and characterized it in its various forms, including rock and glass.
Analysis of the amount of magnesium and sodium extracted from glass, under various temperatures and with various grain sizes, always shows more sodium than magnesium.
What's more, magnesium levels are always significantly lower than necessary for prebiotic RNA folding to function properly. Researchers found that the missing part of the process is convective heat flow.
"This situation changed greatly when a very likely heat flow, due to the high level of geological activity within the prebiotic environment, was added," said biophysicist Christof Mast of Ludwig Maximilians University of Munich in Germany.
"We have shown that the combination of basaltic rock and simple convection currents can give rise to the optimal relationship between Mg and Na ions under natural conditions," he added.
The prominent temperature gradient in the narrow slits and pores of the basaltic glass creates the convective flow required for salt optimization and also moves more ions against the current. This process creates what is known as thermophoresis.
Studies show that the processes of convection and thermophoresis increase the amount of magnesium ions in the mixture thereby creating conditions in which self-replicating RNA can occur. Scientists think a similar type of chemical reaction may have occurred on Earth 4 billion years ago.
Salt leaching from this basalt, is found abundantly in the Earth's mantle. This information fits into the template for the "RNA world" hypothesis to work. What's more, this fact expands the possibilities in terms of the salt mixture that may have helped give rise to life.
"The principles shown here apply to a wide range of salt concentrations and compositions, and as such, are highly relevant to various scenarios of the origin of life," conclude the researchers.
