It's no secret that wolves, foxes, and dogs are highly social animals. But beyond all the wagging, pawing and yipping we like to try to interpret, canids may have yet another way to communicate. New research hints at the possibility that dogs and their ilk could be sending each other signals with their eyes.

A team of Japanese researchers looked at pictures of nearly every canid species and found that those with highly social pack and hunting behaviors were more likely to have easily-visible eyes. They then watched some of those species interact in zoos and concluded that those with eyes that were easier to see were more likely to be social. The results were published in a study in PLoS One on June 11.

"What this study shows is that there’s a correlation between facial markings and sociality and the need to communicate," said zoologist Patricia McConnell of the University of Wisconsin-Madison, a dog behavior researcher who was not involved in the study.

The scientists organized 25 different wild canid species according to their facial features (using around a dozen photos of individuals from each species) into three groups and then looked to previous research to characterize the social behavior of each group.

PLoS

Group A contained species that have irises much lighter than their pupils, and faces with markings that make their eyes easy to locate. These animals, which include species like the gray wolf, coyote, and golden jackal, are more likely to live in social groups and hunt as part of a pack.

In group B were species where only the facial markings indicated the position of the eyes and the pupils weren't visible, such as the maned wolf, the dingo and the kit fox. These canids tend towards solo life or bonded pairs, and hunt alone.

The canid's eyes in group C were camouflaged, with no markings either within or around the eye to mark it from the rest of the face. Group C were mostly the more primitive canid species, like bush dogs, tanukis, and African wild dogs, which tend to live in social packs, but mostly hunt alone.

To field test their groupings, the researchers went to Japanese zoos and observed gazing behavior in a species from each of the groups: gray wolves (group A), fennec foxes (group B), and bush dogs (group C). All three species gazed at each other about the same number of times, but the wolves held their gazes significantly longer than the foxes or bush dogs. The gray wolves also did twice as many distinct playful postures as the other two species.

These graphs show that canids with highly visible eyes tended to be more social, and hunted in groups. PLoS

Gaze communication isn't unheard of in the animal kingdom, and humans are prime examples. Scientists believe one of the reasons we have white surrounding our irises is so we can pick up on what other people are looking at. If certain canids communicate with gaze, they probably rely mostly on having a high contrast between the iris and the pupil, rather than the sclera (the technical name for the white of the eye).

McConnell says that canids are big communicators, but we still have a long way to go before we understand all the channels they use. "You can say without a question that a canid's entire body is an information source," she said. This study, while it does show a link between gaze and sociability, isn't conclusive.

One way to take these tests further would be to camouflage the eyes of heavy-gazing canids and watch how it affects their social interactions. And maybe you could be the one to do it. McConnell says her field is suffering from a lack of researchers.