Ochman was originally trained as a population geneticist at the University of Rochester, where he received his Ph.D. in 1984. Technical advances in molecular biology prompted his switch to studying the organization and evolution of bacterial genomes and for the past three decades he has been investigating molecular evolution and the diversity of interactions among microbes. After a postdoctoral stint in the Department of Biochemistry at the University of California, Berkeley, he worked as a research scientist on the Human Genome Project and in 1987 moved to Washington University to study the evolution of bacterial pathogenesis. Prior to joining the faculty at The University of Texas at Austin, Ochman held faculty appointments at the University of Rochester (1991-1998), the University of Arizona (1998-2010), and Yale University (2010-2013).