When a mouse finds a crumb, it does something remarkable: it takes a single, careful sniff—coordinating its hands, head and breathing in perfect timing—much like a human leaning in to smell a cantaloupe at the grocery store. Now scientists have discovered that these two mammals share something surprising underneath their very different sniffing styles.
Researchers at Northwestern University found that mice and humans use the same basic brain system to process smells. Even though a mouse's quick sniff lasts far less time than a human's deep inhale, the underlying tempo and mechanism are fundamentally the same. Two complementary studies, both published in the journal Science Advances, showed that these olfactory systems have been preserved through millions of years of evolution.
"The true similarity is this single sniff, but it's not just a sniff," said John M. Barrett, a research assistant professor of neuroscience at Northwestern's Feinberg School of Medicine. "Mice even move their hands while sniffing, which shows it's volitional—they're doing it on purpose."
The first study, led by Mang Gao and Barrett in the lab of Gordon M. G. Shepherd, built a robotic multicamera system to track mice as they foraged and ate. They discovered that mice occasionally bring food briefly to their noses before continuing—a behavior that looks remarkably humanlike. The mice timed their single sniff to the exact moment food reached their nose, precisely coordinating their movements.
The second study, led by first author Andrew Sheriff with corresponding author Christina Zelano, found that humans organize odor information at a rapid rate within a single sniff. This form of olfactory brain processing looked remarkably rodentlike, confirming that both species rely on the same underlying neurophysiology—the brain's motor and rhythmic building blocks.
Together, these findings suggest something important: mammals all rely on a similar basic system for smell, with each species adapting the same design to fit its own needs.
The researchers say this discovery could have real implications for human health. Changes in sniffing behavior have been linked to conditions like autism, Alzheimer's disease, and Parkinson's disease. Understanding the basic wiring of our smell system might help doctors detect these conditions earlier or develop better treatments.
"Knowing we have this evolutionarily conserved set of mechanisms helps us understand how mammalian brains work, which could ultimately help us understand how they fail in pathology," Sheriff said. "It helps us know how the brain works so we know how to fix it when it doesn't work."
In other words, what scientists learned from watching a tiny mouse take one careful sniff might someday help protect human brains from disease.