In April 2016, Tony Stretton’s lecture to undergraduate biology students began on an ordinary note, until members of the UW Varsity Band marched into the room with a surprise salute in honor of his 80th birthday. Stretton wiped away tears of joy as the class clapped and cheered, a wide grin on his face.

At an age when most professors have the word emeritus attached to their titles, Stretton, a professor of zoology, still relishes his work with students both in and out of the classroom. “I’m very lucky to have the job I have, and it’s tremendous fun,” he says.

This fall, Stretton is starting his 47th year of teaching at UW–Madison, using science as a vehicle to impart his unflagging love of learning and discovery. Yet he finds as much meaning in the people he encounters as in the pursuit of knowledge itself.

Stretton trained in his native England during the advent of molecular biology, and his list of colleagues is a Who’s Who of the biologists enshrined in textbooks. As a young scientist, he started working in the same lab as Francis Crick just a few years after Crick and James Watson reported the structure of DNA, work that would earn them a Nobel Prize.

Now Stretton is teaching students two to three generations his junior in one of the hottest undergraduate programs on campus — brain science. Student interest in neurobiology at the UW has steadily grown since it was introduced as an option for biology majors nearly 20 years ago. That interest supported the launch of a new neurobiology major last fall, which has seen rapid growth. More than 450 students enrolled in the first year.

The brain represents a worthy challenge for anyone looking to push the boundaries of human understanding. And with technological advances in recent decades, “you’re able to ask questions that were inconceivable when I was a kid,” Stretton says.

His own research focuses on how tiny but abundant bits of protein, called neuropeptides, work in the nervous system to drive behavior. He is spurred on by the puzzle of figuring out how many complex pieces fit together to add up to the wonder that is a living creature, even a simple worm.

“He’s just so curious about everything,” says Jennifer Knickelbine ’10, PhD’17. She joined his lab as an undergrad to help prepare for medical school, but was so taken with the process of inquiry — and Stretton’s contagious excitement about it — that she ended up staying after graduation. This spring she earned her doctorate, likely as Stretton’s final graduate student.

His lab has at times become a refuge for students struggling to find their place. Joanne Yew PhD’03 joined Stretton’s research group midway through graduate school, when she faced serious doubts about her future in research. “I thought about quitting science,” she says.

Stretton was on Yew’s graduate committee and offered her space in his lab to regain her footing. “I said I’ll try it out, but I might quit after a year,” Yew recalls. “But he had this great humanity about it: life is complicated, people change, and he was willing to deal with that complication. I always felt like he wanted the best for me.”

Yew now runs her own lab at the University of Hawaii at Mānoa.

“He believes in the best possible version of each person,” she says. “And that makes the person live up to that version.”

That genuine, compassionate interest in people shines through in all his interactions. “All of his mentoring extends beyond the lab and beyond coursework,” Knickelbine says. But his guidance is powerfully nonjudgmental and always based on “you could” rather than “you should.”

“It’s tremendous in a mentor, that whatever you say, you know you’re not going to disappoint him,” she says.

For students willing to put in the effort, Stretton creates opportunities to succeed, from extensive office hours in campus cafés to “second chance” exams that offer opportunities to boost grades. He received an Undergraduate Mentoring Award in 2016, bolstered by more than a dozen glowing letters from alumni.

Yet Stretton would say he has gained as much from his students as they have from him. He estimates that he’s taught some 20,000 undergraduates, in addition to a couple dozen graduate students and several postdoctoral trainees.

“In science, you always have to be ready to abandon what you think you know,” Stretton says, before launching into a story about witnessing Crick become ecstatic upon learning his pet theory had just been disproven by another scientist, and how powerfully it influenced him as Crick’s young colleague. “You have to have an open mind and be prepared to entertain all sorts of things. And that’s certainly true of my interactions with people. I love interacting with people who have all different backgrounds and assumptions.”

Reflecting on his days as a young researcher, he chuckles at his own naïveté. “I’m probably still immature, but I feel I’m more mature than I was then,” muses the 81-year-old. “I think I have a little bit more perspective. And I thank my students for that.”

Story originally published in the Fall 2017 issue of On Wisconsin Magazine.