Sniff, Sniff: Study Finds New Form of Rat Communication

Rats caught sniffing at each other is not only because they smell each other, but a new study released Thursday showed that rats have the ability to communicate with one another by sniffing.

A new study from Case Reserve University School of Medicine published in Current Biology reveals that sniffing also serves as a way to communicate a rat's social status to another.

This unexpected discovery may help to identify brain regions critical for interpreting communication cues as well as help identify which brain malfunctions can lead to complex social disorders.

Research reported in Current Biology, said that rats seen sniffing at each other are in fact communicating information about an individual's social status.

Daniel W. Wesson, with the CWRU School of Medicine, said in a statement that rats "sniff each other to signal a social hierarchy and prevent aggressive behavior." In the observed encounters between the rodents, the more dominant rats acted as primary sniffers, while subordinate rat would then respond by breathing slower.

Wesson used radio telemetry recordings of nasal respiration in a series of trials in order to determine the reactions of rats when other rats sniffed in their direction.

"We know that rats and other animals can communicate through vocalizations, physical contact, odors, and also visual displays. To find that there was an undiscovered form of communication these animals had been using right in front of us this whole time was truly a neat experience," Wesson added.

Wesson's theory is that the dominant rat was displaying a "conflict avoidance signal" similar to a large monkey or ape walking into a room and pounding its chest. In the case of monkeys, the subordinate animal might shrink and look away. With rats, the appropriate response is for the subordinate animal to simply decrease its sniffing.

Sniffing as a form of communication highlights the complex social lives of animals. "It opens the door to a totally new line of understanding complex, microstructured social behaviors," Wesson says.