Wolves Communicate with their Eyes?

Wolves and dogs possess certain ocular characteristics that allow them to communicate with other members of their species using their eyes alone, suggests a new study published in the journal PLOS ONE, giving new meaning to the common phrase "puppy-dog eyes."

The color of the face around the eye, the eye's shape and the color and shape of both the iris and the pupil are all part of the complex eye-based communication system, according to the research, which could apply to humans as well.

Sayoko Ueda of the Tokyo Institute of Technology at Kyoto University led the study, comparing 25 different types of canines. The researchers broke the studied species down into three groups based on their facial coloration and gaze:

A-type means both the pupil position in the eye outline and eye position in the face are clear; B-type indicates only the eye position is clear; and C-type is when both the pupil and eye position are unclear.

Researchers noted that those canines that had clear pupil and eye positioning (such as wolves) tended to live in group environments, whereas those with unclear pupil and/or eye positioning (such as foxes) tended to be solitary.

"A-type faces tended to be observed in species living in family groups all year-round, whereas B-type faces tended to be seen in solo/pair-living species," Ueda and colleagues wrote.

Ueda and his team thereby deduced that these were all adaptive traits which enabled the canines that hunt in packs and live in groups to communicate with one another via gaze signal.

Animals like foxes, which exemplify the B-type, however, only rely on their eyes some of the time to exchange information.

And then for the C-type, seen in animals like bush dogs, their all-dark eyes blend in with their faces. This makes it difficult to predict their behavior, given that you cannot see where their gaze is. The researchers point out that "various predators camouflage their eyes to increase their hunting success."

Researchers also suspect that the white of the eye - called the sclera - even evolved to offset the darker hues of the iris and pupil in members of the A-type group. This includes wolves, dogs as well as humans.

Since humans fall into the same category as these ever-watchful canines, it's possible that these findings reveal something about the way we communicate with each other as well.