Charles Darwin was a scientific giant who explained how evolution of organisms have taken place by natural selection. However, he never gave any insight into how life originated. Although a number of studies have been done and are still now going on, none studied how genes and genomes were originated except the late Dr. Susumu Ohno. Since successful publication of his epoch-making book entitled “Evolution by Gene Duplication” in 1970, Dr. Ohno had gradually developed not only his view of the origin of genes but also his own view of evolution. Regarding repetition as the “order”, he believed that evolution took place in a direction from the “order” to the “disorder”. He speculated that a small number of nucleotides formed an oligo-nucleotide fragment and the following repeating processes of this fragment created a prototype of gene at the origin of life. The subsequent mutations led eventually to emergence of a particular gene, which acquired an encoding capability of a protein function associating with amino acids and RNAs. He had proved it by examining nucleotide sequences of immunoglobulin genes. Moreover, the gene music was not his indulgence, but rather his scientific conduct of showing how repetition was dominated over the whole region of nucleotide sequences of a gene.
Actually, evolution by gene duplication was an excellent idea that while the original gene can retain its original function, the other copy duplicated can have a freedom of obtaining new function (neofunctionalization), modifying the original function (sub-functionalization) or even losing the function (non-functionalization). It clearly explained how the gene can evolve by increasing the number of genes. He extended this idea to genome evolution, suggesting that the ancestor of vertebrates experienced at least two-round genome duplications. Such a huge reservoir of freely changeable genes obtained from genome duplication in the vertebrate genomes, enabled them to enjoy creation of various body plans as well as high-ordered control systems including the central nervous system. He also coined the term “Junk DNA”, which has been misunderstood by many scientists, because “Junk DNA” can be reusable sometime in the future while ”rubbish DNA” is merely discarded.
Dr. Ohno’s view was different from the late Dr. Motoo Kimura’s neutral theory of molecular evolution in which stochastic nature such as random genetic drift dominates the evolutionary destiny of organismic populations.
Dr. Ohno was a scientist who pursued unique ideas and innovative concepts through his entire scientific life. He was, indeed, a genius from whom we still learn a lot.