One of the basic properties of life is its ability to reproduce itself. Despite all the diversity that we observe, at the molecular level the reproduction of all organisms follows the same plan: a certain type of polymer – a nucleic acid – in the shape of a double helix, DNA, governs the process through a mechanism printed’. It is he who preserves and transmits biological information. But there is another type of nucleic acid, RNA, which is responsible for articulating the instructions contained in DNA , such as protein synthesis.
DNA duplication requires the presence of proteins, but protein synthesis requires DNA. So how did DNA first appear? How to get out of this vicious circle? The most plausible hypothesis suggests that RNA was the first carrier of genetic information. This is so because RNA molecules have been shown to have the ability to do double duty: as primitive DNA and as protein. In this way, in an initial phase, instead of the DNA-protein duo, the RNA would carry out both the storage and the manipulation of the information. This initial step is called “the RNA world.”
A cosmologist has calculated the probability that there is life outside of Earth
Now, how did RNA appear? Could it appear by chance, by simple trial and error? What is the probability of that happening? It is believed that a viable RNA, valid for life, must have at least 40 to 100 nucleotides (the molecules with which both DNA and RNA are built). It is here where the work published by Tomonori Totani in the Scientific Reports magazine takes place. According to Totani, “current estimates suggest that it could not appear in the volume of space that we consider that the observable Universe occupies.” If the observable universe contains about 10 to the 22nd stars, by sheer chance only an RNA of about 20 nucleotides could appear.
But Totani argues that the real universe is larger than the observable one due to inflation, a period of rapid growth of the universe on the first shelves of its birth. Hence Totani concludes that the real universe must contain more than 10 to 100 stars “and if this is the case, the most complex RNA structures that support life are more than probable, they are practically inevitable”.
This is not the first time that a scientist has thrown himself into the arena of mathematics to ‘prove’ the inevitability of the existence of life outside our planet. In 1998, the mathematician Amir C. Aczel published the book Probability 1 where, using basic concepts of probability theory (and a series of assumptions about what the universe is like), he reached the conclusion that life is, as the biochemist said. and Nobel Prize winner Christian De Duve, a cosmic imperative.
Referencia: Totani, T. Emergence of life in an inflationary universe. Sci Rep 10, 1671 (2020). https://doi.org/10.1038/s41598-020-58060-0
