Web Exclusives:Features

April 24, 2002:

Alumni Spotlight:
Sensing is believing
Emily Liman '85 studies missing genetic link in humans

Catpion: Liman is a leading researcher in the field of pheromones.

Taped to the door of Emily Liman '85's laboratory at the University of Southern California is a New Yorker cartoon depicting a couple at a cocktail party. The underlying caption reads: "There's no, no in your eyes, but yes, yes in your pheromones."

Ironically, Liman's research as a molecular biologist suggests that the organ dedicated to sensing pheromones in many mammals — the vomeronasal organ (VNO) — is, like the appendix, nonfunctioning in humans. Her papers on the topic have made headlines in scientific and pop-culture publications alike, from Wired magazine to the Boston Globe.

Pheromones are a chemical substance produced by humans and animals that serve as a stimulus to other individuals of the same species. They are responsible for regulating the mating patterns in a host of animals, from mice to bees to moths. It's not that humans don't emit pheromones, says Liman. Rather, our VNO, located in the nasal passage, lacks the necessary gene to communicate these signals to the brain.

Prior to joining the USC faculty in 1999, Liman served as a post doc at Massachusetts General Hospital and was the first to pinpoint the TRP2 molecule as an important player in transmitting pheromone signals in mice. She also found that humans lack this gene, rendering the VNO inoperative.

When and why did we lose the ability to sense pheromones using the VNO?

Together with a colleague at USC, Liman is currently exploring this very question. For her latest study, funded by the National Institutes of Health, Liman is focusing on the DNA of primate species. Her findings suggest that the loss of pheromone detection may coincide with an increased dependence on vision.

Liman has always been drawn to the field of sensory perception, a topic that first inspired her to study biology at Princeton. "There is a direct link between the sensory system and our behavior and experience," she says. As an undergraduate, Liman devoted her independent research to the study of animal behavior. For her senior thesis, she devised a series of experiments to determine the methods by which squirrels are able to relocate the nuts they've hidden.

Liman delved into the field of molecular biology while earning her Ph.D. at Harvard University. Although she had originally intended to study vision, she became interested in electrophysiolgy — the study of electrical impulses within cells. Her doctoral work focused on ion channels, the pathways by which chemicals are transformed into electrical impulses.

After earning her doctorate in 1992, she saw the opportunity to make an impact in the field of olfaction and joined the lab of leading Harvard neurobiologist Linda Buck as a postdoctoral fellow. At that time, Buck had just made a major discovery by identifying 1,000 unique receptor molecules that detect odors and, in various combinations, transmit different smells to the brain. Liman was charged with finding a similar system for pheromone detection.

By Tamar Laddy '94

Tamar Laddy is a film student at the University of Southern California.