Horses and human share facial expressions

Horses and humans use remarkably similar facial expressions to convey their emotions, suggests a new study.

Researchers from the University of Sussex discovered that horses use muscles beneath their facial features—including their nostrils, lips and eyes—to alter their expressions in different social situations.

The experts identified 17 discrete facial movements in horses by analysing video footage of a wide range of natural horse behaviour, as well as carrying out an anatomical investigation of equine facial muscles. In comparison, 27 facial movements have been observed in humans, 13 in chimps and 16 in dogs.

In addition, the study recorded a striking similarity between many human and horse expressions, such as widening of the eyes in association with fear. The researchers believe that this suggests an evolutionary parallel in the way different species use their faces to communicate.

Study co-lead author, doctoral researcher 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 in horses, and how many of them are similar to humans.’

The Sussex team, in collaboration with researchers from the University of Portsmouth and Duquesne University, have used the findings to develop a method of recording horse expressions known as the Equine Facial Action Coding System (EquiFACS). With the help of the EquiFACS, the experts will now be able to explore exactly how equine expressions correspond to horses’ different emotional states.

Co-lead author Professor Karen McComb explained: ‘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 that the findings could provide valuable insights for veterinary and animal welfare practices.