Investigating the question as to how life could emerge long ago on the early Earth is one of the most fascinating challenges for science. Which conditions must have prevailed for the basic building blocks of more complex life to form? One of the main answers is based upon the so-called RNA world idea, which molecular biology pioneer Walter Gilbert formulated in 1986. The hypothesis holds that nucleotides—the basic building blocks of the nucleic acids A, C, G, and U—emerged out of the primordial soup, and that short RNA molecules then formed out of the nucleotides. These so-called oligonucleotides were already capable of encoding small amounts of genetic information.
According to the new theory, a decisive element at the beginning was the presence of RNA molecules that could adorn themselves with amino acids and peptides and so join them into larger peptide structures. “RNA developed slowly into a constantly improving amino acid linking catalyst,” says Carell. This relationship between RNA and peptides or proteins has remained to this day. The most important RNA catalyst is the ribosome, which still links amino acids into long peptide chains today. One of the most complicated RNA machines, it is responsible in every cell for translating genetic information into functional proteins. “The RNA-peptide world thus solves the chicken-and-egg problem,” says Carell. “The new idea creates a foundation upon which the origin of life gradually becomes explicable.”