Without the spark that ignited organisms billions of years ago, none of us would still be here. Scientists continue to be fascinated by the mystery of how this spark was created.
Research that looked at the origins of life on the Earth has revealed that a mix of salts and heat from molten rocks could have led to self-replicating biomolecules.
This self-replication is a crucial part of the RNA world hypothesis. It is the idea that ribonucleic acid (RNA) can store biological information as well as perform necessary structure folding to allow life to grow and evolve to the present state.
Scientists looked at the magnesium (Mg), and sodium (Na), as they might have been in Earth's earliest years. RNA folding requires a high concentration of doubly charged magnesium and a lower level of singly charged sodium.
"Accordingly, it begs the question of which environments might have provided suitable conditions for prebiotic processes in early Earth." The leaching of salts form basalt is one possibility that could lead to saline environments, according to an international research team.
Basalt, which is a primary partial melting of the Earth’s mantle, is one of the most common rock types in the Earth's early-crust, as well the crust of other terrestrial worlds in the Solar System.
Basaltic glass is a form of basalt that naturally occurs on Earth. The team synthesized it by using melted basalt and quickly cooling it (by contact with sea water for instance). They then characterized it in all its forms, including rock and glass.
Analyses of the amounts of sodium and magnesium extracted from glass under various temperatures and with different grain sizes always revealed significantly more sodium than magnesium.
Furthermore, prebiotic RNA folding was not functioning properly if magnesium levels were significantly lower than they should have been. Researchers discovered that convective heat flows were the missing piece of this process.
"The situation changed significantly when heat currents that are very likely have been present, due to the high levels of geoological activity expected to be found in prebiotic environments, were added," said Christof Mast, biophysicist at the Ludwig Maximilians University of Munich, Germany.
"We have demonstrated that simple convection currents and basaltic rocks can create the ideal relationship between Mg ions and Na ions in natural conditions."
The temperature gradients found in the basaltic glasses' narrow cracks, pores and pores create convective flows that are necessary for salt optimization. They also move more ions against currents creating what is known as thermophoresis.
The study found that convection and the thermophoresis both increase the magnesium ions in the mixture, which creates conditions for self-replicating DNA. Similar chemical reactions could have occurred on Earth four billion years ago.
The research indicates that the template for the RNA-world hypothesis to work is fulfilled by the leaching of basalt salts. It also opens up new possibilities for salt mixtures that could have contributed to the sparking of life.
The researchers wrote in a published paper that the principle they have demonstrated is applicable to many salt compositions and concentrations.
Nature Chemistry published the research.
