RNA can form spontaneously as component molecules filter through basalt glass, which could explain the origins of life on Earth – and tell us where to look for it on other worlds, according to new research. The researchers admit the discovery leaves some questions unanswered, but say it provides a clear and surprisingly simple answer to one of science’s biggest questions.
The theory of evolution and genetics combine to beautifully explain how the simplest forms of life could evolve into the world we see today. However, they did not resolve how these early life forms might appear, a point repeatedly made by creationists scoffing at the idea of ”something out of nothing”. Even non-creationists see a problem, with the structure of RNA described as; “A Prebiotic Chemist’s Nightmare”
The nucleotides that form the basis of DNA and RNA have been found in meteorites, but explaining how they come together has proven to be much more difficult. A paper in the journal Astrobiology claims to fill this most vital gap, showing that basalt glass causes nucleoside triphosphates to fuse into RNA chains.
One thing that the Earth did not lack at the time when life appeared was basalt glass. “For several hundred million years after the formation of the Moon, frequent impacts coupled with abundant volcanism on the young planet formed molten basalt lava, the source of basalt glass,” said the co- author, Professor Stephen Mojzsis of the University of Colorado at Boulder, in a statement. “The impacts also evaporated water to dry land, providing aquifers where RNA could have formed.”
No extreme conditions are required – the authors demonstrated an impressive rate of synthesis for RNA molecules 90-150 nucleotides long at 25°C (77°F) and pH 7.5, with some lengths up to 300 nucleotides.
Given enough raw materials; “A small impact region on the Hadean surface containing only a few tons of fractured, water-soaked glass could have had the capacity to produce nearly one gram of RNA per day,” the authors write. Therefore, they conclude; “Polyribonucleotides were available for Hadean environments if triphosphates were.”
Meanwhile, evidence for the presence of nucleotide bases in some meteorites continues to grow, suggesting that these could have been delivered to early Earth from space. These bases are transformed into nucleosides in reduced atmospheres, such as they existed on the primitive Earth after impacts of asteroids. The team members have previously demonstrated that nickel, abundant in some meteorites, catalyzes nucleosides and phosphate to form triphosphates.
This leaves the question of whether these RNA molecules were sufficient to trigger life. Biologists have long postulated a “world of RNA” where RNA precedes DNA and the proteins it forms. There remains debate over how long RNA needs to last before it can sustain Darwinian evolution, with estimates ranging from 50 to 5,000 nucleotides. Even though the minimum is longer than the strings demonstrated here, it’s easy to imagine that slightly different circumstances could result in longer strings.
“The beauty of this model is its simplicity. It can be tested by high school students in chemistry class,” said Dr. Jan Špaček of Firebird Biomolecular Science, who was not directly involved in this study.
If the paper is accurate, we really have basalt to thank for our existence. Other materials found on early Earth, such as quartz, did not cause nucleotides to bond in the same way.
Mars was also rich in basalt glass at the equivalent point in the history of the two planets. Unlike Earth, much of this remains near the surface, available for verification by future missions.