Theory and Reality of Evolutionary Biology
Abstract of the lecture
I was a normal boy when I was young and had no particular interest in becoming a scientist. This situation suddenly changed in 1946 when I lost my left eyesight by explosion of an ignition equipment of a war-time bomb. This accident forced me to stay in a clinic for about one month, and during this period I thought about my future life seriously for the first time. My interest for studying population genetics and evolution occurred in the first college year mainly because I discovered that I could use my talent of mathematics in this field. At that time evolutionary biology was largely speculative and based on the study of morphological characters, which are strongly affected by environmental factors. In my judgment this was not a serious scientific discipline. However, population genetics was more solid and dealt with the theoretical basis of evolution, animal and plant breeding, and medical genetics at the gene level. I therefore decided to study mathematical population genetics and tried to make it useful for understanding long-term evolution of organisms. Fortunately, around 1960 the molecular approach of evolutionary study was introduced, and we could develop new evolutionary theories by taking into account molecular data. One of my first studies at this time was concerned with the effect of gene duplication on phenotypic evolution. This study predicted that vertebrate organisms contain a large number of duplicate genes and pseudogenes (nonfunctional genes). Thirty years later, study of genomic sequences proved that this was indeed the case. I also developed the theory of genetic distance for measuring the extent of genetic divergence between populations. I then applied this theory to human populations and concluded that the first splitting of human populations occurred between Africans and non-Africans about 100,000 years ago and that non-African populations later migrated to occupy the rest of the world. Recent genomic data again support the major aspects of this conclusion. This genetic distance theory is now widely used in evolutionary biology and conservation biology of various organisms. I also developed a neighbor-joining method of phylogenetic analysis, which has been cited more than 33,000 times by now. Furthermore, I developed a method for measuring the extent of natural selection at the DNA sequence level, which is now used as a standard method of studying evolution. I also analyzed the evolutionary pattern of many immunological and non-immunological genes controlling phenotypic characters. On the basis of these studies, I developed a new evolutionary theory called “Mutation-Driven Evolution” (Oxford University Press, 2013).