We can clearly see animals’ emotions through their behavior, whether that’s dogs filling up with glee when we grab their leash or elephants mourning a loss in their herd, there is clearly some feeling going on here.

While communication between animals and humans remains at a divide, we do understand that they use sounds to express themselves in certain ways. Thanks to thousands of hours of pig grunt recordings and an international collaborative effort, however, the squealing creature’s emotions have finally been able to be deciphered.

Groups from the University of Copenhagen, the ETH Zurich, and France’s National Research Institute for Agriculture, Food and Environment (INRAE), teamed up to study audio from pigs in different conditions and stages of life.

They figured out that short grunts with minor fluctuations in amplitude are “happy” grunts. These are the sounds the pigs make when suckling from their mothers or when reunited with family members. Negative emotional situations like separation, fights, castration, and slaughter, resulted in high pitched squeals and screams from the animals.

This data was put into a machine learning algorithm to train it to recognize the pigs’ emotions. Currently, the technology can correctly classify around 92% of the calls to the correct emotional response, with the team hoping to improve this further with more data and understanding.

The team also hopes to input this algorithm into an app so farmers can use it as a monitor of their pigs’ psychological wellbeing. Once we can qualify the emotions of our livestock, the better we can create optimal conditions for them to live in.

“With this study, we demonstrate that animal sounds provide great insight into their emotions. We also prove that an algorithm can be used to decode and understand the emotions of pigs, which is an important step towards improved animal welfare for livestock,” says Elodie Briefer who co-led the study.

According to the United Nations Food and Agriculture Organization, livestock farming accounts for 14.5 percent of global greenhouse gas emissions. Further research and understanding of animals as living creatures could help to persuade public opinion against high-emission factory farms.

Source study: Scientific Reports – Classification of pig calls produced from birth to slaughter according to their emotional valence and context of production