HORSES study each other's ears in order to understand what their fellow equine friends are thinking, a new study has revealed.
Like humans the animals read each other's faces for visual cues - but unlike us they gather important information from their stablemate's ears.
The findings, which have come from a University of Sussex study, have been published in a leading scientific journal.
Mammal communication experts Jennifer Wathan and Professor Karen McComb set up an experiment to see which cues horses relied on when they had an option on where to feed.
Each horse was led to a point where it was released and allowed to choose between two buckets. On a wall behind the buckets was a life-sized photograph of a horse's head facing either to left or right.
The researchers found that if either the ears or the eyes of the horse in the picture were obscured, the horse being led made a random choice between the two buckets. However, if the ears and eyes were visible, then the horse used these directional cues to guide their choice.
Ms Wathan said: “Previous work investigating communication of attention has focused on cues that humans use - body orientation, head orientation and eye gaze. But no one had gone beyond that.
“We found that in horses, their ear position was also a crucial visual signal. In fact, horses needed to see the detailed facial features of both eyes and ears before they would use another horse's head direction to guide their choice.”
She added: “Most people who live and work alongside animals with mobile ears would agree that the ears are important in communication, but it has taken science a while to catch up. We naturally have a human-centric view of the world and as we can't move our ears they get rather overlooked in other species.”
Horses, like many mammals that were once hunted by predators, can rotate their ears almost 180 degrees.
The position of a horse's ears is understood to indicate their mood. When they are flopping down, it means they are relaxed while if they are pinned back they are angry.
When a horse is interested in something, it pricks up its ears and swivels them towards whatever it is that has caught their attention.
Professor McComb said: "This study emphasises that animals other than primates are aware of subtle differences in facial expression and can use these to guide the decisions that they make. Fine scaled facial movements can indicate important changes in attention and emotional state and are likely to be crucial in determining social behaviour in a wide range of animals."
The findings are published in Current Biology journal.