Scientists know that humans, chimpanzees, and other primates can convey surprising amounts of information by means of a glance and tilt of the head. But what about animals with eyes on the sides of their heads, like deer and horses? What kind of social cues do they use to communicate?
Now, mammal communication experts report that, at least for horses, a great deal of information is conveyed through the position of the animal’s ears as well as its eyes.
To find out which facial cues equines use, the scientists placed two buckets of feed in front of a wall with a life-size photograph of a horse’s head. The head faced either left or right.
They then released 24 horses, one at a time, and let them choose which bucket to dine from. If the eyes or ears of the pictured horse were covered, the freed horse randomly selected either bucket for its dinner.
But if the eyes and ears in the photo were visible, the horse (such as the one in the photo above, pictured with study author Jennifer Wathan) used these cues to guide its choice, and most often picked the bucket that the pictured horse was facing, as in this video.
The study, reported today in Current Biology, serves as a reminder that creatures with faces shaped differently from those of humans and other primates can nevertheless exchange social signals, the scientists say. None of this is likely to surprise people who work with horses or dogs, they note, but then it sometimes takes a while for science to catch up.