11. Protein World Hypothesis

It is not known whether metabolism or genetics came first. The main hypothesis which supports genetics first is the RNA World hypothesis and the one which supports the metabolism first is the Protein World hypothesis or otherwise known as Protein Interaction World hypothesis or GADV- Protein world; which is a hypothetical stage of abiogenesis which assumes that life emerged as a self-reproducing and expanding system of protein interactions. The GADV- Protein World hypothesis was first proposed by Kenji Ikahara in 1985. GADV stands for the one letter codes of four amino acids, namely, glycine (G), alanine (A), aspartic acid (D) and valvine (V), the main components of GADV proteins. In this hypothesis, it is argued that the prebiotic chemistry before the emergence of genes involved a stage where GADV- proteins were able to pseudo-replicate. This idea also suggests that proteins worked as enzymes first, producing metabolism. After that DNA and RNA began to work as container of genes.

Kenji Ikahara

Proteins act as enzyme which is essential for today's lives and some amino acids are formed from more basic chemicals in the Miller-Urey experiment are some of the evidences which supports the Protein World hypothesis which make this hypothesis more evolutionarily plausible and contrary to the mainstream RNA World hypothesis and also has greater explanatory power.