Fig. 21. [GADV]-protein world hypothesis on the origin of life. The hypothesis anticipates that life could be originated from [GADV]-protein world, where [GADV]-proteins were amplified by themselves through pseudo-replication. It is supposed that the simple amino acid composition of [GADV]-proteins composed of only four amino acids (Gly [G], Ala [A], Asp [D] and Val [V]) made it possible to pseudo-replicate [GADV]-proteins in the absence of genetic function.