He is a professor emeritus at the University of Washington and a former senior fellow at Howard Hughes Medical Institution Janelia Research Campus.
[1] As a graduate student, he continued to study hormonal control of insect behavior at Harvard University where he received his PhD in 1970.
On his second sabbatical in 1993, Truman traveled to the Australian National University in Canberra, Australia, to research grasshopper metamorphosis hormones with Eldon Ball.
[1] In 2016, he retired from the Howard Hughes Medical Institute and returned to the University of Washington to pursue research at Friday Harbor Laboratories.
[2] While still in graduate school at Harvard, Truman identified an insect neurohormone now known as the eclosion hormone, which mediates moth ecdysis.
These results confirmed Truman's previous findings that the circadian clock is located within the brain and that the factor mediating eclosion behavior is hormonal.
Some of Truman's most influential work outside of chronobiology involves how hormones alter the nervous system to influence behavior in insect models.
Their model organism, the hornworm moth (Manduca sexta), was chosen because it has a well-studied endocrinology and its large size allows for the use of standard electrophysiological and neuroanatomical techniques.
Among many changes was the finding that upon onset of metamorphosis, vast cell death sweeps through nests of larvae that are at the end of larval life.