Masatoshi Nei

Masatoshi Nei is Evan Pugh Professor of Biology at Pennsylvania State University and Director of the Institute of Molecular Evolutionary Genetics since 1990. He was born in 1931 in Miyazaki Prefecture, in Kyushu Island, Japan. He became an associate professor at Brown University in 1969, and Professor of Population Genetics at Center for Demographic and Population Genetics, University of Texas at Houston in 1972.

He founded the journal Molecular Biology and Evolution in 1983 and the Society for Molecular Biology and Evolution in 1993, together with Walter M. Fitch.

He made important contributions to the fields of the evolutionary genetics and molecular evolution, and developed a number of statistical methods used in the field of molecular evolution. Among them, the best known and most widely used are the statistic to measure the genetic distance between populations (Nei's genetic distance), GST or FST statistic to measure the extent of population subdivision, and the neighbor-joining method to reconstruct phylogenetic trees (in collaboration with Naruya Saitou).

He proposed neomutationism for the mechanism of phenotypic evolution. In his theory, though it is still controversial, new phenotypic characters or genotypes are generated by mutation and natural selection merely weeds out the genotypes that are less fit to the environment. In other words, natural selection has no creative power. It is a modern version of Thomas Morgan's idea and is based on recent studies of molecular basis of phenotypic evolution. It is a theory competing with neo-Darwinism developed by Fisher, Haldane,  Wright, and  Mayr. Recently, studying the evolution of multigene families controlling olfaction, immune system, etc., he obtained results that support his theory.

He is a member of the National Academy of Sciences since 1997. He was awarded the International Prize for Biology in 2002, and the Thomas Hunt Morgan Medal from the Genetics Society of America in 2006. He is an honorary member of the Genetics Society of Japan and the Japan Society of Human Genetics.

Dr. Nei is still active, studying mainly the evolution of multigene families.