Researchers have found humans are able to glean insights into the feelings of creatures including pigs, horses and goats based on their vocalisations.

The team say the findings suggest certain information within sounds, such as how intense an animal’s emotions are, appears to be conveyed in a similar way across species.

"People probably base their decisions on their knowledge of how humans sound when they’re more or less aroused … because arousal, which is linked to stress pathways, is a system that is well conserved across vertebrates," said Dr Elodie Briefer, co-author of the research from the University of Copenhagen.

They also looked at whether people could determine whether an animal was expressing a positive or negative emotion.

"We cannot really rely on what we know from humans because it varies a lot between species – there are lots of differences in how species express emotions, even closely related ones," said Briefer.

Writing in the journal Royal Society Open Science, Briefer and colleagues report how they recorded vocalisations from six animal species – horses, pigs, goats, cattle, Przewalski’s horses (wild horses) and wild boars. The team noted whether the sound was made when the animal was aroused – as determined by a high heart rate or movement – and whether the sound was made in a positive context, such as anticipating food, or a negative context, such as being isolated.

For humans, the team used existing recordings of meaningless strings of speech spoken in rage or fear to represent higher and lower emotional intensity – or arousal – respectively, and in an angry or joyful way to suggest a negative or positive context.

The researchers then asked 1024 participants from 48 countries to each listen online to pairs of the sounds.

For each species, participants were played four pairs of vocalisations from which they had to rate the emotional intensity of the sound as high or low, positive or negative.

The results reveal that, overall, participants correctly rated the emotional intensity of the subject 54.1% of the time, and type of emotion 55.3% of the time.

"If we take it to the next level, we can very likely easily train people to recognise the sounds," she said, noting that could help those working closely with animals – from farmers to pet owners – to understand them better.

"In the past, scientists used to focus on physical health when assessing animal welfare. Nowadays, most of us recognise the large role that emotions play."

The Guardian