The fact that animals are sentient beings is fundamental to our concern for animal welfare. It is also acknowledged in EU law. Yet, despite the central role animal sentience plays in welfare, there is still scientific resistance to crediting animals apart from humans with having emotional lives.
So, how do we try to assess emotions in animals other than humans?
Well, three core components of emotions have been identified: physiological, behavioural and subjective. The first two can be readily measured objectively in studies. But how do we assess how an animal actually feels?
When there is no common verbal language we can look at a person’s facial expressions and use these to assess how he or she is feeling. Expression of emotions in humans has been extensively studied through changes in facial features. Of course the more different an animal and its’ face is to a human the more difficult this method becomes.
However, some attempts have been made, such as descriptions of facial expressions relating to pleasurable tastes in rats as in humans.
But what about assessing how a farmed animal is feeling?
Scientists have taken a range of different approaches. Here's one such approach.
It has been shown that individual recognition in farmed animals such as sheep and cattle is partly based on facial features. Researchers in France have now studied sheep's facial features and postures and attempted to find convenient physical indicators to reliably infer their emotions.
Compared to other mammals sheep have more simple facial muscles and thus don’t appear to have a wide array of facial expressions. However, they do have several muscles for rotating their ears. The researchers wondered whether measuring ear postures in sheep could be used to accurately infer their emotions. And they decided to find out.
First they identified sixteen discrete ear positions – forward and lowered, forward and raised etc. They then filmed three groups of sheep to record how they changed their ear positions in different circumstances. They assessed the three elementary components of emotions. Suddenness and familiarity of a visual event was assessed by slowly or quickly showing them familiar or unfamiliar objects, negative contrast by drastically reducing a food reward, and control by controlling access to a food reward.
Previous studies have shown that sheep appear to have the potential to feel a wide range of emotions, including fear, anger, rage and despair. The researchers now found that they could link specific ear postures with specific emotional experiences. For example, the backward ear posture which is associated with unfamiliar and uncontrollable unpleasant situations could express fear, the raised ear posture displayed in response to an unfamiliar but controllable unpleasant situation could characterise anger and the asymmetric ear posture that is mainly displayed in response to sudden situations could express surprise. These findings support the intuitive knowledge of people such as farmers who work closely with sheep and have learnt to understand their expressions.
Interpretation of ear postures could be used to assess and improve farming practices from the viewpoint of sheep by helping us to understand what a given animal is feeling at a certain time. The researchers noted that findings from assessment of emotional states in sheep may be readily transferable to other closely related prey species.
Other scientists take a more holistic approach to assessing how animals are feeling by looking at their whole bodies and behaviour rather than focussing on certain features.
This experiment, and other like it, show that by adapting and applying models developed for humans in a manner appropriate for each different species, we can increase our knowledge about the emotions other animals can feel.