You might be asking, “Where’s the RNA’s involvement?” Well, no one is really sure yet. It is accepted that RNA predated DNA. However, scientists have been unable to synthesize RNA in conditions similar to the hypothesized environment of early Earth. One interesting theory that came out of our inability to synthesize RNA is that there was a pre-RNA, an intermediary between life beginning and the presence of RNA.
RNA has a role in abiogenesis, but RNA is not responsible for the origination of life. RNA is responsible for the evolution of life, however. It is the theory of the RNA World. The rationale behind this theory is that RNA is capable of being a genetic information storage molecule, and a catalytic compound. The ability of RNA to act as a catalyst is, perhaps, one of the most exciting discoveries in the field of abiogenesis. The rationale for this is that in order for RNA to be synthesized, the components have to be joined together. This is infinitely more challenging if this process has to be done without any catalytic support. In addition, the process of replication requires catalytic energy. So, it was determined that RNA could be an ideal first molecule due to the ability to preform vital functions (evolution and replication) on its own, independent of other molecules.
However, the idea of the RNA World as the first prebiotic system of life has been replaced with a predecessor of the RNA World, aptly named the pre-RNA World. This theory came about with the discovery of molecules such as pyransosyl RNA (pRNA), threose nucleic acid (TNA), and peptide nucleic acid (PNA). These molecules are structurally similar to RNA, but simpler. The implications of these simpler molecules as predecessors of RNA is that the potential precursors would be easier to synthesize than RNA in an abiotic world.
When hypothesizing the conditions of the early Earth, four elements are thought to be dominant – methane (giving the carbon necessary for life), ammonia (giving the nitrogen necessary for life), hydrogen gas, and water. Life is thought to begin with the correct mixture of these gases as well as a “life spark.” What is interesting is that, as validated by multiple scientists, the probability of the correct combination of gases combining with the proper “life spark” is practically nil.
We all know we are stardust. But did we know we are also improbable miracles?
