When insect biologist James Truman arrived at University of Notre Dame in the 1960s, all he knew about his future journey was that he wanted to major in biology.
He had no inkling that it would lead to 50 years of research following a passion for metamorphosis, a National Academy of Sciences membership, and a paper that invited intense media interest years after he became an emeritus professor.
“When I came to Notre Dame, I had no idea what biologists did,” joked Truman B.S.’67, who was elected to the National Academy of Sciences in 2022. “Maybe work for a national park? Work in a zoo? Other than that, I didn’t have a clue.”
Truman, professor emeritus of biology at the University of Washington in Seattle, studies growth and molting in insects, as well as their metamorphosis — the process that is best known in butterflies, where the caterpillar eventually transforms into a chrysalis, and then finally emerges as an adult with wings.
His research revealed the hormones that cause the shedding of the old exoskeleton at the end of each molt, and established how steroid hormones act at metamorphosis to recycle larval neurons for adult insects to reuse.
His 2023 study, published in the journal eLife, followed the fates of dozens of neurons in a fruit fly’s brain as the insect went through metamorphosis. The research showed that while many neurons from the larval stage persist into the adult stage, they “rewire” in a different fashion. The result? The insects have no memory of their lives as larvae. The work has been applauded by scientists worldwide, and was featured in The New Yorker and Wired, among other publications. It is a culmination of his years of research, some completed in tandem with his wife, Lynn Riddiford, who was inducted into the National Academy of Sciences in 2010.
Truman’s first mentor was George B. Craig, Clark Professor of Biology at Notre Dame, whose work with mosquitoes during the mid- and late-20th century changed the direction of vector biology. Truman met Craig and joined his laboratory as an undergraduate at the end of his freshman year, and “that’s when I knew what I wanted to do,” Truman said.
Not only was Craig an excellent mentor, but when Truman saw Craig working in the laboratory on a Saturday, wearing a casual shirt in place of his white shirt and tie, the idea to become a researcher and professor clicked.
“He would be at the bench playing with the mosquitoes,” Truman described. “And it was this, just this joy in research! And I suddenly realized that was academics, and involved more than just what occurred in the classroom.
“I used to think that professors were like glorified high school teachers, but then I realized there was this whole other area, where universities generated knowledge as well as conveying knowledge.”
After leaving the tutelage of Craig’s lab at Notre Dame, Truman landed at Harvard University where his doctoral thesis demonstrated that “body clocks” could be located in the brain and transplanted between species. He started with moths, because different moth species emerge from their cocoons at different times of the day.
“I took two moths that emerged at different times, one in the morning and one at night, and swapped the brains between the two,” Truman described. “And the species that should emerge in the morning then emerged at night, and vice versa. It was the first demonstration that a biological clock could be transplanted from one individual to another.”
Also, since the transplanted brains did not reconnect with the nervous system of the host, it had to be initiating the emergence behavior by a substance released into the circulation. This eventually led to the discovery of a new family of insect hormones.
“My second interest was in metamorphosis itself,” said Truman, who spoke on Zoom from his office that features an oversized print of a moth on the wall behind him. “You know, how do insects undergo this dramatic change? How do organ systems of the larva transform to function in the completely different body of the adult?
His interests in the field eventually focused on the nervous system. He wanted to understand how the brain changes as a caterpillar transforms into an adult, or a maggot becomes a fly. In more primitive insects like crickets and grasshoppers, an individual that hatches from the egg is a miniature version of the adult and its brain is wired the same as an adult’s. However, insects that goes through complete metamorphosis, like a fruit fly, the issue is quite different — the larva that hatches looks nothing like a fly, and its brain is built to control the body of a maggot, not a fly.
“I have become intrigued with trying to understand how a larval stage evolved in the first place, and how embryonic development was diverted to make a reduced, rewired larval brain, rather that a mini adult brain as is seen in crickets and grasshoppers,” Truman said.
Originally from Akron, Ohio, Truman earned his doctoral degree in biology from Harvard University in 1970. He remained at Harvard as a junior fellow until joining the faculty at the University of Washington in 1973. He retired from there in 2007 and became a group leader at the Janelia Research Campus of the Howard Hughes Medical Institute.
Truman returned to Seattle in 2016 and worked in Washington’s Friday Harbor Laboratories and continues to do the research he enjoys.
Though his inspiration began with working in Craig’s lab, that decision came after some discovery — and Truman felt his varied background as an undergraduate student at Notre Dame came in handy once he got to Harvard.
“There was no problem getting a project together and doing the work, because the courses I took at Notre Dame prepared me for anything,” he said.
And he had words of advice for students in the College of Science.
“You don’t want to specialize too much as an undergraduate — You want to keep that breadth,” he said.
After all, it could lead to a job at a zoo, in a national park … or to the National Academy of Sciences.