The eye of the wolf

For humans, following the gaze of another person is an instinctual response, a way of detecting things in our environment and reading non-verbal messages. But it's also a crucial form of communication for other members of the animal kingdom.

To a wolf, a look to the side from another member of the pack out on the hunt could signal the presence of prey - the message being, "dinnertime."

Researchers at the University of Vienna in Austria have put wolves' gaze-following abilities to the test, in a study of nine hand-raised animals. Previously, select species of primates and birds - as well as the red-footed tortoise - were the only animals known to share humans' capacity for tracking another's gaze.

The study's authors, biologists Friederike Range and Zsofia Viranyi, found that this evolutionary ability isn't limited to apes and avians.

"Our results provide the first evidence that a non-primate mammalian speices, the wolf, is also able to follow the gaze of others, not only into distant space but also around barriers," the paper read, which was published Wednesday in the online journal PLoS ONE.

The next level

Most social animals are able to track another creature's visual cues. But it's another thing to recognize a creature's gaze, and then follow it around an obstacle, such as a tree or a boulder. Range and Viranyi cite one theory - that animals displaying "high levels of cooperative and competitive interactions" are more likely to share the capacity for repositioning themselves to track another animal's look.

Wolves, with their clear-cut hierarchies starting with the alphas, as well as their pack mentality and cooperative hunting skills - seem to fit the bill.

When it comes to tracking prey, the ability to see where a fellow wolf is looking and follow it enables faster detection of something to eat, as well as quicker responses to potential threats.

A video filmed during the course of the study illustrates just how quickly wolves are capable of following visual cues – both from other canines and humans. The experimenter stands before a gray and brown wolf. The animal is panting in the sun, sitting in the middle of a grassy yard. After several seconds of interaction, the experimenter keeps her body in the same position but turns her head - eliciting a fast response from the wolf, which jerks its head in the same direction.

Three wolves from Austria, two from Switzerland, and four from the United States, some of them siblings, were involved in the study. The researchers tested their aptitude on gaze-following behind an obstacle once a month, starting when the wolves were 16 weeks old. Two weeks earlier they began testing the animals' ability to follow humans' gaze - indicated by a turn of the head or eyes to the side - without any barriers.

By the time the wolves were more than three months old, they could follow gazes into distant space. The young pups' ability to track a look developed relatively early on compared to other species. One possible explanation offered by the study: playful wolf pups start interacting with other members of the pack at a tender age.

Still, it took the canines longer to follow a gaze around an obstacle - though this skill consistently improved with age. A similar phenomenon was observed with ravens, albeit with a slightly different timeline. Researchers took this to mean that cognitive mechanisms for both types of gaze-following develop separately.

The human-animal link

Humans seldom stop to think about the evolutionary advantages that come with being able to recognize another person's head and eye orientation - to look in the same direction, at the same thing. The study's authors called it a "central feature of social life and communication in humans." But what about communication across species?

Wolves' ability to follow the gaze of another animal has clear implications for understanding how that capacity evolved among different species. But the animal's ability to follow the gaze of a human may hit closer to home.

For the researchers, it speaks to "the sensitivity of domestic dogs toward human communicative clues" - and thus, the bond between man, and man's best friend.

Author: Amanda Price
Editor: Stuart Tiffen