Critter faces convey much

In search of ponies

link Sharna Johnson

A smile, bewildered forehead wrinkles, droopy eyes, an angry glare, a grimace of pain — facial expressions serve as clues to what someone is thinking or feeling in a way that goes beyond words.

Responses to physical or mental circumstances and events, expressions are externalizations that literally put a face to what is more often than not unseen.

So important are expressions, in fact, that people commonly project human emotions and thoughts on animals based on expressions that appear to mimic those they use and understand.

And as science continues to delve into the inner workings of the minds of animals, particularly as they compare to humans, increasing evidence is being found that highlight the similarities between people and their critter cousins — showing that those expressions may be shared more than we think.

Though they can be different in appearance, it’s well understood that animals make facial expressions that, just as with humans, can convey what is going on inside their minds.

However, understanding if and how these expressions are interpreted between the members of a species is an area of great curiosity that continues to prompt studies on whether animals recognize expressions in their own kind, what those expressions mean and what they do with that information.

Even Darwin believed that non-human animals used facial expressions to communicate, a belief that has been proven through centuries of primate studies, according to Satoshi Nakashima, a Japanese social cognition psychologist who has found evidence of the same traits in rats.

Not only do rats have distinct facial expressions that convey pain, Nakashima concluded in a study published in April, they also see and understand expressions of pain in each other — expressions that look very similar to how pain is displayed on human faces.

To evaluate whether rats could distinguish between the facial expressions of other rats, researchers used photographs showing rats with normal expressions, rats exhibiting grimaces of pain, and photos in which the bodies or faces of rats had been blurred. The photos were then displayed in multiple rooms of a test box and 104 rats were released into the box one at a time while researchers recorded their responses as they explored.

Overall, the study found rats avoided the rooms in which photos of rats with expressions of pain were displayed, spent more time in and showed a preference for the rooms that contained the photos of normal rat expressions, and showed no reaction to the blurred photos.

Understanding why they reacted to pain expressions the way they did is unclear, because in other studies, Nakashima noted, rodents have been found to go to the aid of others in distress, however he speculated that in this case, they avoided the rats that appeared to be in pain because they were afraid that the cause of the pain would affect them too. He also theorized the rats likely discounted the blurred photos because they looked unnatural.

Despite the questions it sparked about how expressions affected behavior, the study succeeded in showing rats, already known to use vocal, scent and body language cues, also place importance on expressions as a layer of their communication with one another — a discovery that further expands the number of animals known to rely on the face as an important part of listening and being heard.

As the list of creatures with complex and multifaceted communication traits similar to humans continues to grow, so does knowledge that may someday change communication as we know it — in the meantime, it probably wont hurt to smile at other species more often … just in case.

Sharna Johnson is a writer who is always searching for ponies. You can reach her at: [email protected]