Susanna Mitro '11 Makes Headlines with Research on Telling Age Based on Scent

Susanna Mitro '11
Susanna Mitro '11

The olfactory ability of humans is often considered the least perceptive of the five senses. A new study, however, headed by Susanna Mitro '11, attempted to refute this common misconception and, in the process, ended up disproving an old urban legend.

In the summer of 2010, Mitro began collecting body odor samples for her biology honors thesis on a subject that had interested her, she says, "since high school" when she first heard about "t-shirt sniffing studies." For the next year, she conducted research studies at the University of Pennsylvania's Monell Chemical Senses Center with principal investigator Johan Lundström to measure how accurately subjects could determine a person's age based solely on their body odor.

Participants in the study were asked to differentiate between young (20 to 30 years old), middle (45 to 55 years old) and old (75 to 95 years old) age groups based on body odor samples. After analyzing the data with help from Associate Professor of Statistics Steve Wang, Mitro found that people were successfully able to discern between these three age groups based solely on smell. Furthermore, test participants were able to identify members of the old age group just from their smell, but were unable to do so for the two younger groups, which very much interested her. "It suggests that some component of the body odor of the elderly is distinctive and similar across both sexes," she says, "which wasn't the case for the younger body odors."

As for the mythological "old person smell," researchers found that the natural scent of the elderly does not conform to the stereotype. The octogenarians' odor was deemed both less intense and less unpleasant than that of the two younger demographics.

On May 30, Mitro published her study online in the journal PLoS ONE, produced by the Public Library of Science. Within 24 hours, news of her work had appeared in Scientific American, the Washington Post, Nature, The Telegraph (U.K.), and the Sydney Morning Herald, among many others.

"It's a topic that is intrinsically interesting to people," says Professor of Biology Sara Hiebert Burch, Mitro's departmental adviser. "When people would read Susanna's poster, they would ask 'What got you interested in this field?' She would just reply 'I've always been interest in human odor.'"

After graduating with high honors as a biology major with minors in Japanese and psychology, Mitro travelled to the Gifu Prefecture of Japan, a small rural area, where she is currently teaching English to middle school-aged students. This fall, she will return to the U.S. and begin a Master of Public Health in epidemiology at the University of Michigan.