Usually when someone calls you a “horse face”, it’s meant as an insult. (Though, better than being a horse’s a**.)
But new research from scientists at the University of Sussex has found that the facial expressions of humans and members of the equine family are surprisingly similar in some ways.
The findings, published Thursday in the journal PLOS One, revealed that like humans, horses use muscles underling their nostrils, lips, eyes and other facial features to change expressions in a variety of different social situations. The study also indicates that there could be evolutionary parallels among different types of animals in terms of how faces are used to communicate.
In a statement, the authors explained their work builds on previous studies that found facial cues are important for horses to communicate. It also establishes a new coding system, The Equine Facial Action Coding System (EquiFACS), used to identify different types of individual facial expressions on the basis of underlying muscle movements.
Devised by researchers from Sussex, the University of Portsmouth, and Duquesne University, the EquiFACS system identified a total of 17 discrete facial movements (also called “action units”) in horses. In comparison, humans had 27, chimpanzees had 13 and dogs had 16, they said.
EquiFACS reveals extensive facial movements of horses
“Horses are predominantly visual animals, with eyesight that’s better than domestic cats and dogs, yet their use of facial expressions has been largely overlooked,” explained co-author doctoral student at Sussex Jennifer Wathan in a statement. “What surprised us was the rich repertoire of complex facial movements in horses, and how many of them are similar to humans.”
“Despite the differences in face structure between horses and humans, we were able to identify some similar expressions in relation to movements of the lips and eyes,” she added. “What we’ll now be looking at is how these expressions relate to emotional states.”
As part of their study, Wathan and her colleagues reviewed video footage of a wide range of naturally-occurring horse behaviors, the university explained in a statement. By doing so, they were able to identify the different movements that the creatures can make with their faces, and this led to an analysis of the facial muscles responsible for the various motions. Each movement that they identified was assigned a unique code, the research team added.
“It was previously thought that, in terms of other species, the further away an animal was from humans, the more rudimentary their use of facial expressions would be,” co-lead author Karen McComb, a professor at the university, said. “Through the development of EquiFACS, however, it’s apparent that horses, with their complex and fluid social systems, also have an extensive range of facial movements and share many of these with humans and other animals.”
“With EquiFACS we can now document the facial movements associated with different social and emotional contexts and thus gain insights into how horses are actually experiencing their social world,” she added. “As well as enhancing our understanding of social cognition and comparative psychology, the findings should ultimately provide important information for veterinary and animal welfare practices.”
—–
Feature Image: Thinkstock
Comments