Rats sniff to show who is top dog

CASE WESTERN RESERVE (US) — When rats sniff each other they’re doing more than simply smelling. They sniff to show social hierarchy and to prevent aggression, a new study shows.

The discovery may help scientists identify brain regions critical for interpreting communications cues.


When two rats approach each other, one communicates dominance by sniffing more frequently, while the subordinate signals its role by sniffing less. If the subordinate doesn’t do so, the dominant rat is more likely to become aggressive to the other.

Daniel Wesson, associate professor of neurosciences at Case Western Reserve University, who drew upon previous work showing that, similar to humans, rodents naturally form complex social hierarchies, used wireless methods to record and observe rats as they interacted.

He theorized the dominant rat was displaying a “conflict avoidance signal,” similar to a large monkey walking into a room and banging its chest. In response, the subordinate animal might cower and look away, or in the case of the rats, decrease its sniffing.

“These novel and exciting findings show that how one animal sniffs another greatly matters within their social network,” Wesson says. “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.”

Published in the journal Current Biology, the findings represent the first new form of communication behavior in rats since it was discovered in the 1970s that they communicate through vocal ultrasonic frequencies. The research provides a basis for understanding how neurological disorders might impact the brain’s ability to conduct normal, appropriate social behaviors.

Wesson’s laboratory will use these findings to better understand how certain behaviors go awry. Ultimately, the hope is to learn whether this new 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 National Science Foundation, the Mount Sinai Health Care Foundation, and the University Hospitals Case Medical Center Spitz Brain Health Fund supported the research.

Source: Case Western Reserve University