Sniffing, a common behaviour in dogs, cats and other
animals, has been observed to also serve as a method for rats to communicate—a
fundamental discovery that may help scientists identify brain regions critical
for interpreting communications cues and what brain malfunctions may cause some
complex social disorders.
Researchers have long observed how animals vigorously sniff
when they interact, a habit usually passed off as simply smelling each other.
But Daniel W. Wesson, PhD, of Case Western Reserve University School of
Medicine, whose research is published in Current Biology, found that rats sniff
each other to signal a social hierarchy and prevent aggressive behaviour.
What the research
Wesson, 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 found that, when two
rats approach each other, one communicates dominance by sniffing more
frequently, while the subordinate signals its role by sniffing less.
Wesson found that if the subordinate didn't do so, the
dominant rat was more likely to become aggressive to the other.
Wesson theorised 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," said
Wesson, an associate professor of neurosciences. "This sniffing behaviour
might reflect a common mechanism of communication behaviour 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
Wesson's findings represent the first new form of
communication behaviour 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 behaviours.
Wesson's laboratory will use these findings to better
understand how certain behaviours go awry. Ultimately, the hope is to learn
whether this new form of communication can help explain how the brain controls
complex social behaviours and how these neural centres might inappropriately
deal with social cues.