FOR those who cherish a close bond with the equine world, it is a compelling study straight from the horse’s mouth, as well as its eyes, lips and nostrils.
Domestic horses share a “rich repertoire” of facial expressions that they change depending on any given situation, scientists have found.
What surprised us was the repertoire of facial movementsJennifer Wathan
A team of researchers from three universities have identified a host of different discrete facial movements which shows horses are even more expressive than chimps, man’s closest living relative in the whole of the animal kingdom.
A study which scrutinises changes in anatomy and muscles pinpointed no less than 17 individual movements in horses, compared to the 13 expressions used by chimps. Humans are capable of 27 such movements.
Those behind the research said they were “surprised” by the variety of looks horses used and admitted their use of expressions had been “largely overlooked” by science.
The breakthrough that came via the Equine Facial Action Coding System (EquiFACS), an observational tool adapted from a similar system used to identify human expressions.
Researchers at the University of Sussex spent hours analysing video footage of horses and found they use muscles underlying their nostrils, lips and eyes in the same way people do.
The study’s co-lead author, Jennifer Wathan, said: “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.
“What surprised us was the rich repertoire of complex facial movements and how many of them are similar to human’s.”
Ms Wathan, who is an associate tutor in psychology and life sciences, said that as yet, it remains unclear how each horse’s different expression relates to mood or circumstances.
She explained: “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. What we’ll now be looking at is how these expressions relate to emotional states.”
Karen McComb, professor of animal behaviour and cognition at the university and co-lead author of the report, said: “It was previously thought that the further away an animal was from humans, the more rudimentary their use of facial expressions would be.
“Through the development of EquiFACS, however, it’s apparent that horses, with complex and fluid social systems, also have an extensive range of facial movements and share many of these with humans and other animals.
“This contributes to a growing body of evidence suggesting that social factors have had a significant influence on the evolution of facial expression.”
The pioneering study, carried out along with researchers at the University of Portsmouth and Duquesne University in Pittsburgh, is published in Plos One, a journal produced by the San Francisco-based Public Library of Science.