Masatoshi Nei

Masatoshi Nei (1931-2023) was a Japanese-born American evolutionary biologist who built many of the statistical tools of molecular evolution. Born in Miyazaki Prefecture, he took his first degree at the University of Miyazaki and his doctorate at Kyoto University in 1959 before moving to the United States in 1969, where he held posts at Brown University, the University of Texas Health Science Center at Houston and, from 1990 to 2015, Pennsylvania State University. He proposed Nei genetic distance and nucleotide diversity, helped develop the neighbor-joining and minimum-evolution methods for building phylogenetic trees, and was a developer of the MEGA software package. He argued for a theory of mutation-driven evolution and for a birth-and-death model of multigene family evolution. With Walter Fitch he founded the journal Molecular Biology and Evolution in 1983.