Senior studies how mole-rats make their Zagat guides

By Kate Becker

When trendy urbanites are in search of a tasty meal, they pick up their Zagat guides and hop on the subway. But naked mole-rats, the most famous (and most nearly hairless) subterranean denizens of East Africa, don't have the luxury of a guidebook when it comes to finding food. So how do these all-but-blind creatures unearth their next meal?

Senior biology major Dara Neuman goes eyeball-to-eyeball with a 26-year-old naked mole-rat from Professor Paul Sherman's lab. Nicola Kountoupes/University Photography

Senior Dara Neuman is working with Paul Sherman, professor of neurobiology and behavior, to find out. A biology major, Neuman had never seen a naked mole-rat (Heterocephalus glaber) when she joined Sherman's lab in the second semester of her junior year. Now her work is culminating in an honors thesis and in a scientific journal article, co-authored with Sherman, that the pair will complete this summer.

She delights in describing the 3-inch-long, sparsely whiskered animals encased in wrinkly pink skin and equipped with sharp claws and teeth for digging underground tunnels. While their appearance -- something like a cross between a gerbil and a steamed dumpling -- charms zoo-goers, it is their behavior that fascinates evolutionary biologists, including Neuman and Sherman.

Neuman says mole-rats are generally regarded as the world's most social mammals -- after humans, of course --and their subterranean social structure resembles that of bees in many respects. For example, colonies of about 75 non-reproductive workers cooperate in serving a single queen and king, the only breeding members of the group. Naked mole-rats dine on roots that intersect their tunnel systems, Neuman says. A single large tuber can sustain a colony for months, but when the rainy season softens the desert's baked clay soil, food scouts must quickly begin extending tunnels in search of new food sources.

Bringing the food back to the colony's nest means traversing tunnels that can be 3 kilometers long, so the food scout needs help from other workers, or "recruits," to harvest the tubers efficiently, according to Neuman. But to a mole-rat's discriminating palate, a tasteless tuber might not be worth the trouble.

So, Neuman set out to discover how the scout communicates food quality to potential recruits. She and Sherman wondered if the scout might inform recruits of the location, quantity and quality of food by doing a "waggle dance," such as bees use to direct hive-mates to high-quality flowers. But after observing mole-rats' behavior in a simulated habitat (a labyrinth of clear plastic tubes in Sherman's climate-controlled laboratory), Neuman concluded that the scout wasn't doing anything special. Instead, the other workers were sniffing the scout to determine what it had eaten.

Neuman observed that this sniffing was concentrated around the scout's mouth and hypothesized that the workers were smelling the scout's breath to assess the appeal of its food find. To test this idea, she is now feeding scouts the blandest thing she can think of: matzo balls made from her grandmother's special recipe, minus the seasonings. After they taste the matzo, some of the scouts are given a squirt of apple-scented "mouthwash." She is currently investigating whether mole-rats with "apple breath" are able to recruit more workers than their unscented colleagues.

At Cornell, Neuman is also active in the Alpha Phi sorority, sings with the Chai Notes, a Jewish a cappella group, and tutors students in biology and genetics. She has spent the last two years as a medical assistant for Gannett Health Services, gaining experience for a future career as a doctor.

When she leaves Cornell -- she plans to enter medical school -- Neuman will take with her not only outstanding academic credentials, including a 4.0-plus GPA and Phi Beta Kappa membership, but the confidence, she says, "to discover on my own instead of just having information handed to me." This, above all, is what Sherman hopes to teach the undergraduates that he invites into his small research group. When students first begin their research, he says, "You have to convince them that they really have the intelligence and the drive to do it. And once they get it -- they're just terrific."