Rats Sniff To Communicate Complex Social Information
March 8, 2013

Rats Sniff To Show Who’s The Boss – Breakthrough Study Finds New Form of Animal Communication

April Flowers for redOrbit.com - Your Universe Online

Checking out their environment by sniffing is a common behavior for dogs, cats and a number of other mammals. A new study from Case Reserve University School of Medicine reveals that sniffing also serves as a method of communication in rats. 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.

One of the most common occasions for vigorous sniffing is when animals come into contact with each other, a behavior that researchers have traditionally passed off as simply a way to get familiar with the odor of the other. However, neuroscientist Daniel W. Wesson found that rats sniff each other in order to signal a social hierarchy and prevent aggressive behavior.

"We know that rats and other animals can communicate through vocalizations, physical contact, odors, and also visual displays," explained Wesson. "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."

Prior studies show that rats, like humans, naturally form complex social hierarchies. Wesson used radio telemetry recordings of nasal respiration to record and observe rats as they interacted and found that when two rats approach each other, dominance is communicated by more frequent sniffing. The subordinate rat signals its role by sniffing less in the interaction. If the subordinate rat sniffed more than it was supposed to, the dominant animal was more likely to become aggressive.

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 cower and look away. With rats, the appropriate response is for the subordinate animal to simply decrease its sniffing.

Even in animals unable to smell, the sniffing exchanges continued. However,  the researchers found that treating the animals with the so-called ℠love hormone´ oxytocin did eliminate the dominant-subordinate sniffing behavior.

"These novel and exciting findings show that how one animal sniffs another greatly matters within their social network," said Wesson. "This sniffing behavior might reflect a common mechanism of communication behavior across many types of animals and in a variety of social contexts. It is highly likely that our pets use similar communication strategies in front of our eyes each day, but because we do not use this ourselves, it isn't recognizable as 'communication'."

This study represents the first new form of communication behavior observed in rats since vocal ultrasonic frequencies were revealed as a communication tool in the 1970s, providing a basis for understanding how neurological disorders might affect the brain's ability to conduct normal, appropriate social behaviors.

Wesson plans to continue his research, using these findings to better understand how certain behaviors go awry. He hopes to understand whether this newly understood form of communication can help explain how the brain controls complex social behaviors and how these neural centers might inappropriately deal with social cues.

The team´s findings were published in a recent issue of Current Biology.