A group of researchers from the Foundation for Applied Molecular Evolution has discovered a possible mechanism for the appearance of a key element for life: RNA. Its appearance would be due to natural processes caused by basaltic lava glass, a material that was widespread on Earth 4,350 million years ago. The study not only gives us clues as to how life could have appeared on Earth, but also on Mars.
The key to the study.
The team, led by Elisa Biondi, has released the results of their study in a article in the magazine Astrobiology. In it, they explain that RNA chains of between 100 and 300 nucleotides can form naturally when nucleoside triphosphates, the individual molecules that link together to give RNA structure, percolate through basaltic lava glass. These nucleosides are themselves composed of a nucleobase linked to a sugar (ribose in the case of RNA, hence the name) and three linked phosphate groups.
Basaltic lava glass would have been a common compound on the Earth’s surface in the stages prior to the appearance of life, which would give free rein to these interactions and therefore to the appearance of RNA chains.
Stephen Mojzsis, co-author of the study, points out that this rock was “everywhere”. A mixture of asteroid impacts and volcanic activity laid the foundations for the appearance of basaltic lava, which after crystallizing would leave behind large amounts of basaltic glass.
The simplest explanation.
There are other theories about the appearance of complex molecular structures such as RNA, but the authors of the study highlight this one for its simplicity. A simplicity that is always preferred when explaining natural phenomena. Simple to the point of being replicable in an institute lab, explains Jan Špaček, a colleague of some of the authors at Firebird Biomolecular Sciences.
Prebiotic evolution, abiogenesis.
The evolution between inanimate compounds on the early Earth and the appearance of life is riddled with gaps and mysteries. We know that our planet cooled enough to allow the appearance of basic chemical compounds about 4.5 billion years ago, and the first signs of life that we have date back to 3.7 billion years ago. This process between the inert and the living is known as abiogenesis.
The study sheds light on a part of this process, but neither its conclusions are definitive nor does it allow conclusions to be drawn about other stages of this process. In steven benner wordsco-author of the study, there are pending questions, “we still do not know how it is that all the RNA bricks had the same overall structure.”
RNA and DNA.
There is some consensus that RNA preceded DNA as an elementary molecule, but the matter is far from settled. DNA is considered too complex a molecule to have been the first to appear, since it requires proteins that only it can generate. A chicken-and-egg problem, according to explains Ester Lázaro, of the National Institute of Aerospace Technology. This is the so-called RNA world, although the situation was most likely more complex, with various compounds coexisting on that early Earth.
Life on Mars.
One of the striking points of this study is that it can be applied beyond Earth. We have long suspected that Mars has hosted life at some point in its history. The appearance of life on the red planet would be consistent with what is proposed in this analysis, since it is a planet with abundant basaltic lava glass. Of course, there is a difference with respect to the earth, since these formations are still on the Martian surface, while on Earth they were buried by tectonic movement.
“If life emerged on Earth through this pathway, then it probably did on Mars as well,” adds Benner. He further concludes that “This makes it even more important to search for life on Mars as soon as possible.”
Image | NASA