Horses understand and react to human facial expressions, suggesting that they get our moods and may even empathize with us.
A new study revealing how horses read human emotions puts horses on the very short list of known animals that understand our facial expressions. Only dogs have previously been shown to have the skill.
"It's possible that horses developed this ability during their 6,000-year co-evolution with humans, or indeed that individual horses learn it during their lifetimes," Amy Smith, who co-led the research, told Discovery News.
Photos: Horses, Humans Share Facial Expressions
"It's been shown in dogs that familiarity improves their ability to recognize emotions, which supports the idea that the ability is based, at least in part, on personal experience," added Smith, who is a doctoral student in the Mammal Vocal Communication and Cognition Research Group at the University of Sussex.
Smith, research co-leader Karen McComb and their colleagues recruited 28 horses from five riding stables in Sussex and Surrey, U.K., for the study, which appeared in Biology Letters. Each horse was shown photographs of men with different facial expressions corresponding to particular moods.
Earlier research found that horses recognize people and horses that they have only seen before in photographs, so they seem to perceive photos as we do. When first presented with photos, however, some horses examine the image from various angles, as if trying to find the rest of the individual.
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The horses' reaction to angry faces was pronounced, the researchers report. The horses viewed these images primarily with their left eye, due to the right brain hemisphere's specialization for processing threatening stimuli. (Information from the left eye is processed in the right hemisphere.)
McComb, a professor of Animal Behavior & Cognition at the University of Sussex, told Discovery News that this outcome, in particular, was very revealing.
"It gives us a real insight into how they are viewing the situation and shows clearly that they see it as negative," McComb explained. "The way in which their heart rate increases also backs this up. So being in a negative mood around horses is not something that goes unnoticed and is likely to have negative impacts on behavior and physiology."