Naked mole-rats (?) kept Sarah Toll in the dark

Sarah Toll displays the experimental apparatus she designed to test mole-rats' vision, in Mudd Hall. Charles Harrington/University Photography

By Roger Segelken

Searching for an undergraduate research topic at Cornell, Sarah Toll could have done the astrophysics of naked singularities. Or the psychology of naked aggression. Instead the senior, who is graduating with honors from the College of Agriculture and Life Sciences, chose a topic guaranteed to elicit the "huh?" response from friends and family -- biology of the naked mole-rat.

"It gave me a chance to tell people what fascinating animals they really are," Toll said. "Naked mole-rats are the most insect-like of all the social mammals. They live in vast, subterranean colonies in Africa where just one female, the 'queen,' is responsible for reproduction and all the others cooperate in foraging for food and raising the young."

Perhaps the joke on the wall, in the Mudd Hall laboratory where biology Professor Paul Sherman keeps one of the world's few scientific colonies of the bizarre creatures and where Toll conducted her research, explains their appeal: "The good thing about being a mole-rat queen is you get all the guys. The bad thing is ... all the guys look like saber-tooth Vienna sausages."

"Actually, mole-rat pups are kind of cute, before they get all wrinkly," Toll said.

"Sarah had the perseverance and scientific creativity to tackle one of the unresolved questions about naked mole-rats -- can they see or are they blind?" said Sherman, who has written several popular and scientific books on Heterocephalus glaber.

But meaningful results don't come easily in ground-breaking science, Toll discovered. The first part was simple enough, demonstrating that H. glaber can perceive light. Naked mole-rats, whose keen sense of smell substitutes for vision in the lightless natural tunnels and darkened laboratory tunnels, conduct 99 percent of their daily activities with their eyes closed. Yet they opened their eyelids when Toll shined a flashlight on them. They also responded when she opened sections of their plastic-tube lab tunnels, simulating a break in their natural tunnel system where predators might enter.

Toll had proved that naked mole-rats look. But do they see?

Two possible proofs of vision, Toll learned from biology Professor Howard Howland, are accommodation (Do eyes attempt to focus?) and acuity (Can eyes track a moving object?). Using a photoretinoscope, Toll took dozens of pictures of infrared light reflecting off the mole-rats' retinas. And with an apparatus she built from a lampshade, covered with black-and-white stripes and spun by an electric motor, Toll watched as mole-rat heads turned -- as if to follow the moving pattern.

The problem was, mole-rats responded similarly to a blank, white revolving drum. Her carefully planned test had failed to prove acuity. Or disprove it, either. Equally frustrating, the mole-rats' tiny eyes are almost too small for the photoretinoscope, which is designed for humans. So it's back to the lab for more accommodation tests, in hopes of completing the vision experiment and publishing her first scientific article, along with the professor.

Not that Toll spent a whole Cornell career in the dark with social animals. She proved her hospitality again and again, beginning as a freshman volunteer host for high school students visiting campus during Cornell Days and culminating this year as chair of the Red Carpet Society. She successfully mustered hundreds of other volunteers to share their Cornell experiences -- and their dorm rooms for a night -- with applicants who are "on the fence" about attending Cornell or other schools that accepted them.

Toll began the hosting duties to help fulfill the public-service requirement for her Cornell Tradition scholarship, she said. The volunteer work went above and beyond -- way beyond -- because she wanted to share her affection for this university with prospective students.

"My first impression, as a visitor, was: 'Wow, this place is big ... but friendly.'" First impressions proved accurate, she says now: "Big place. Lots to learn. Lots to do. Lots of friendly people."

The biology major's undergraduate research and academic record ("Three-point-nine-ish," she estimates for her grade point average) earned a place in graduate school and two fellowships the first year to work toward a Ph.D. in animal behavior at University of Maryland.

"I just realized," she said, "I'll be working with another animal that no one ever heard of." The well-dressed mole-rat? "No, the stalk-eyed fly. Really. They're fascinating creatures. We even have them around Ithaca. You just have to know where to look."