Goats can tell when people are happy or angry, and they prefer to see people smiling, according to a new study published by The Royal Society.
The research, designed to determine the intelligence of goats in understanding human social cues, used 35 goats from a goat sanctuary in the United Kingdom.
The researchers presented the herd with images of happy and angry expressions on the same human face (they used a male and female face for different trials), set up on either side of a pen.
The scientists released the goats into the pen from a gate opposite to the location of both images and then timed the goats' interactions with each photograph to determine their preference.
The study found that the goats' first interactions were more often with the positive face overall and the goats tended to spend more time with the happy expression compared to the angry face.
The authors concluded that "goats can distinguish between happy and angry images of the same person, indicating that they can visually differentiate human faces conveying different emotional valences".
The study also found that the goats preferred to spend time with the happy faces when they were on the right side of the testing pen. The authors theorised that this may be related to a difference in brain hemisphere engagement with happy expressions.
Hemisphere asymmetry in processing positive and negative emotions has been documented in humans before, with evidence to suggest that hemisphere dominance in cognition changes depending on how welcoming or threatening a stimulus may be.
According to past research, dogs are very good at perceiving human facial communication cues because of their domestication as companion animals.
Horses have also been found to react with social intelligence to human angry expressions with increased heart-rate and a gaze to the left (which has been shown to be a reaction to negative stimuli in horses).
Horses also remember the emotional facial expressions of specific humans.
The Royal Society study is the first to indicate that domesticated farm animals such as goats, which haven't been bred specifically to interact with humans, as have horses or dogs, can read facial communication cues from humans.
Goats were first domesticated approximately 10,000 years ago in the highlands of western Iran for their milk, meat, fur, bones, and dung.
New findings show that early selection of goats for breeding was based on the pigmentation, stature, and milking of these animals, rather than their cooperation with humans like dogs and horses.
This research suggests that socio-cognitive adaptations to life with humans isn't limited to the working or companion animals and may be more widespread than previously assumed.