[4] In 1979 Tajima became a graduate student at the University of Texas in Houston, where he was supervised by Masatoshi Nei.
[7] As a graduate student, Tajima was one of several researchers working independently on coalescence theory, which seeks to describe the evolutionary history of a single locus.
His training in phylogenetics and population genetics put him in a good position to explore evolutionary trees with respect to single loci.
[5] In a 1983 paper, published in the journal Genetics, Tajima laid out findings that have since been described as among the "most important results in coalescence theory".
In his paper, Tajima showed that well-known results of "classical" population genetics could be reproduced by using coalescence theory.