Thomas Guy Hallam received his doctorate in mathematics from the University of Missouri in 1965. He began his career as a faculty member in the Department of Mathematics at Florida State University, working in the area of comparison theorems for ordinary differential equations. While at Florida State, he initiated a mathematical modeling course. As his interest in applying mathematics to environmental problems took off, he began taking courses in oceanography and ecology. In 1977, Hallam accepted a joint professorship in the
Mathematics Department and the Graduate Program in Ecology
at the University of Tennessee, Knoxville. During the 1980s and 1990s, Hallam's research group integrated ecotoxicology and population dynamics into a watershed quality assessment tool for the U.S. Environmental Protection Agency. His research in using mathematical models to solve problems in ecotoxicology and ecology inspired him to begin an interdisciplinary program at the university that combines mathematics and biology.