Horses can differentiate between happy and angry human faces.


Researchers previously showed that dogs can identify emotions from human faces. To find out whether horses share this ability, Amy Smith, Karen McComb and their colleagues at the University of Sussex in Brighton, UK, tested the response of domestic horses (Equus caballus; pictured) to photographs of human faces with happy or angry expressions. Horses tended to view angry faces with their left eyes — a sign that they were processing the image using the brain's right hemisphere, which is thought to handle negative stimuli. The animals' heart rates also increased more rapidly in response to angry faces than to happy ones.

The ability of horses to recognize human expressions could have evolved during domestication, the authors say. They add that the animals probably also refine this skill during their lifetimes.

Biol. Lett. 12, 20150907 (2016)