This spring, the School of Arts and Sciences bids farewell to four faculty members whose combined contributions span more than a century of service to Dartmouth.
“These four colleagues represent what Dartmouth hopes for in its faculty: serious scholars and artists who are also dedicated, inspiring teachers,” says Interim Dean of Faculty John Carey. “Their contributions to this institution, to the students they taught, and to their fields will be felt on campus and beyond for years to come.”
The four retiring faculty—Jamie Horton, associate professor of theater; Thomas Jack, professor of biological sciences; Leslie Sonder, associate professor of Earth sciences; and Jeffrey Taube, professor of psychological and brain sciences—represent the range of intellectual life in Arts and Sciences, from the neural mechanics of navigation and the molecular biology of flowers to the geology of the American Southwest and the art of theater.
“One of the things I love most about Arts and Sciences is the intellectual breadth of what we do here,” says Nina Pavcnik, inaugural dean of the School of Arts and Sciences. “These four colleagues capture that breadth beautifully, and each of them brought the depth of commitment to their work, their students, and this community. Dartmouth has been very lucky to have them.”
Jamie Horton: A life in theater
Before Jamie Horton set foot in a Dartmouth classroom as a professor, he had already been part of its theater world. In 1972, just after graduation from Hanover High School, he appeared with the Dartmouth Summer Repertory Company. He went on to spend more than 20 years as a principal actor and director with the Tony Award-winning Denver Center Theatre Company, playing more than 80 leading roles and helping develop new work for the American stage.
He returned to Hanover in 2006, and stayed for two decades.
As associate professor of theater, Horton taught acting and directing and served for more than 13 years as the department's director of theater, responsible for producing the yearly repertoire of main stage and student productions. His directing credits at Dartmouth range from Shakespeare to musicals: Julius Caesar, Spring Awakening, Urinetown, and most recently The School for Lies, a David Ives comedy of manners that served as his final Dartmouth production in February 2025.
Horton’s connection to the professional stage never went dormant. In 2011, he appeared in a Department of Theater production of Eurydice—and was spotted by someone who encouraged him to submit an audition tape for Lincoln, directed by Steven Spielberg. Eight months later, he was on set in Richmond, Va., playing U.S. Rep. Giles Stuart in a cast that included Daniel Day-Lewis, Sally Field, and Tommy Lee Jones. He also played George Orwell in the world premiere of Orwell in America at Northern Stage, a production written and directed by Dartmouth colleagues Joe Sutton ’76 and Peter Hackett ’75 that later moved to an Off-Broadway run in New York. Other Northern Stage appearances include Scrooge in A Christmas Carol, Lloyd Dallas in Noises Off!, and the title role in King Lear.
But it is his teaching that students and colleagues return to when they describe what Horton leaves behind. “While Jamie’s talent and intelligence are undeniable, it’s his character that looms largest for me,” said Max Samuels ’15, who studied under Horton and later became a colleague. “When I’m at my best—as an actor and a person—you can be sure that Jamie’s influence is a key ingredient."
Horton has been consistent about what draws him to the work. “Like most theater artists, I’ve always believed in the power of theater to make change—change in those who create it as well as those who make up its audience,” he said. “The greatest joy as a teacher of theater is to see growth in one's students, to witness their talents take shape and flourish, regardless of their level of previous theater experience and ultimate career path.”
Horton looks forward to continuing his acting career following his retirement from Dartmouth and will be performing next season in The Weir at Northern Stage.
Thomas Jack: From the lab to the classroom
How does a single fertilized cell become a complex organism with hundreds of different cell types? That question drove Thomas Jack’s research from the start of his career. He had spent his graduate years at Yale studying fruit flies, and by the time he joined Dartmouth’s Department of Biological Sciences in 1993, he had made the switch to addressing this question in plants.
Arabidopsis thaliana is a small weed in the mustard family that was just emerging as a model organism for genetic research. Jack’s lab focused on flower development, specifically the genes that give each floral organ its identity—the molecular instructions that distinguish a petal from a stamen. When those genes are inactivated, the results are striking: for example, petals become sepals, stamens become carpals. These mutations fascinated developmental biologists for their precision and their strangeness, and they anchored Jack’s research program for more than two decades.
In 2012, Jack was recruited as an inaugural fellow of PULSE, the Partnership for Undergraduate Life Sciences Education, a program whose mission is to close the gap between what education research says about student learning in STEM and what actually happens in classrooms. Dartmouth benefited from the work directly. In 2015, Jack and two biological sciences colleagues redesigned Biology 13, Gene Expression and Inheritance, converting it from a lecture-based course into a “flipped” classroom: students watch lecture material as videos before class, with class time devoted to group problem-solving. The course has been taught in this format for 10 years.
Jack also served as department chair for 12 years, during which time he helped shepherd the planning and construction of the Life Sciences Center, which opened in 2011. His involvement was hands-on enough that architect Natalie Gentile named a stairwell in the building after him.
Colleagues say his door has always been open. “Whether in his office or in a queue outside of his office, there is a constant stream of faculty, students, and staff seeking him out for help, guidance, or just a few minutes of his good company,” says department chair Magdalena Bezanilla.
In retirement, Jack plans to stay in the area and continue the PULSE work, with site visits to biology departments planned through at least 2028. Looking back, he appreciates a career that evolved far beyond where it began. “That’s the nice thing about academia,” he says. “You have the flexibility to make those changes.”
Leslie Sonder: The physics of mountains
“How does the Earth work? And why?” Those two questions have anchored Leslie Sonder’s research across nearly four decades in Dartmouth’s Department of Earth Sciences.
Sonder earned her PhD at Harvard studying the forces that stretched and widened the American West over millions of years, and arrived at Dartmouth in 1988. Her early work focused on large-scale continental extension and strike-slip deformation, including a highly cited 1999 paper, “Western United States Extension: How the West Was Widened.” In later years, she expanded into collaborations tracing the movement of water through soils, plants, and the atmosphere, bringing the same modeling tools to bear on an entirely different set of physical systems.
Answering the big questions, she says, almost always requires mathematics. “Most of the time, answers to these sorts of ‘why’ questions require mathematical modeling—developing and solving the mathematics that describes the physics of natural processes.”
Teaching gave Sonder another way to make that work matter. She developed EARS 5, Natural Disasters and Catastrophes, and taught it for more than 20 years to classes of up to 300 students per term. For a certain generation of Earth Sciences undergraduates, she is perhaps best known for her segment of the department’s field program, the Stretch, where she led students through the Basin and Range province of the southwestern United States, teaching them to use gravimeters and magnetometers in the field. As undergraduate major advisor since 2004, she has kept her door open to any curious student. “I have heard undergraduates remarking about how welcoming the department is,” says department chair Meredith Kelly, “and in large part, I thank Leslie for establishing and maintaining that model.”
Sonder also chaired the department from 2001 to 2004 and helped establish the Joseph P. Obering Fellowship, the department's first dedicated source of postdoctoral funding. “The expertise and energy that postdocs bring to the Earth Sciences department is unmistakable,” she says, “and I’m proud to have contributed to the beginning of our ability to bring them to Dartmouth."
Outside the classroom and lab, Sonder has been a longtime member of the Dartmouth Symphony Orchestra, serving as its librarian since the early 2000s. In retirement, she plans to lean further into music—she plays viola in both orchestral and chamber settings—alongside travel, rowing, reading, and volunteering.
Jeffrey Taube: The brain’s internal compass
The brain keeps track of which direction you’re facing, constantly and automatically, below the level of conscious thought. Jeffrey Taube has spent his career figuring out how.
In 1990, the year he joined the Department of Psychological and Brain Sciences, Taube published a pair of papers that would define a field. Working with rats, he was the first to describe head-direction cells—neurons that fire only when an animal faces a particular direction, functioning as the brain’s internal compass. The discovery established Taube as the world’s foremost authority on how the sense of direction is constructed in neural circuits.
“My research has focused on the neural mechanisms that underlie our abilities to navigate—how we find our way from one place to another,” Taube says. Over the following decades, his lab systematically characterized how head-direction cells work, how they are wired together, and what they mean for behavior—a body of work spanning more than 114 peer-reviewed articles cited over 18,000 times, supported by continuous federal funding for more than 30 years. The work was co-authored by many of his trainees, a number of whom went on to establish their own research programs. “He put Dartmouth on the map in systems neuroscience,” says department chair and professor Brad Duchaine.
Among his proudest moments as a mentor: graduate student Patrick LaChance was awarded the Lindsley Prize from the Society for Neuroscience—the field’s top recognition for a PhD thesis in behavioral neuroscience, presented at the society’s annual meeting. “Seeing my student awarded this prize was quite the honor,” Taube says.
In the classroom, Taube directed the department’s undergraduate systems neuroscience course for many years, introducing students to the neural mechanisms underlying behavior—and to actual brain specimens. He was known for breaking the ice on the first day by juggling, and for giving undergraduates the chance to record head-direction cells themselves. The research itself took him beyond Hanover. As a co-investigator on a NASA-funded project, he conducted experiments aboard the agency’s reduced-gravity aircraft—nicknamed the “vomit comet” for the weightlessness it simulates—to study how the brain’s directional system responds when gravity disappears.
Taube was also a driving force behind two of the department’s most significant programs. He helped develop and launch Dartmouth’s neuroscience major in the early 2000s, which now enrolls around 40 students a year, and played a key role in establishing the Integrative Neuroscience graduate program. He also co-founded iNAV, a biennial international gathering that brings together researchers using both human and animal models to study navigation. The conference has run for 12 years and draws more than 200 attendees each time.
In retirement, Taube plans to pick up where he left off before graduate school, when he spent four years traveling through Europe and Asia. He has already begun, with photography workshops in Namibia and Patagonia behind him and trips to eastern Greenland and the Galapagos planned for 2027.