Professor Keith Kendrick, the Babraham Institute, Cambridge.
Part of the show Animal Communication, Sexual Signalling and Emotions
Chris - Tell us a bit about your work.
Keith - We're very interested in finding out and understanding whether sheep are in many way like humans in the way that they use facial cues to recognise each other. They use the same specialised parts of the brain for doing that as we do. Of course, we don't just derive identity from faces, but we also derive emotional information from facial expressions. It occurred to us to ask the next question, which was if sheep can recognise and use faces, can sheep use faces to recognise emotional states? We looked at this not only in sheep, but looked at whether they can identify emotion in their human carers.
Chris - Do sheep have particularly expressive faces?
Keith - Not particularly, but they don't have the musculature that we do to generate the almost hundreds of different facial expressions that we can. However, they do show quite marked changes in the appearance of their faces when they are fearful or stressed. If you look at the same animal's face when it's happy, such as after a meal, it looks relaxed and its ears are laid back and its eyes are almost closed. If you socially isolate a sheep, which they don't like, their heart rate shoots up, and their ears start going back and their eyes bulge. Their nostrils often flair too. It's quite easy to tell the difference if you see the pictures.
Chris - It seems odd that they should be able to recognise human facial expression though. Why should they be able to do that?
Keith - The face recognition system is very much an expertise based system. You have the hardware in the brain that allows you to use it whether you're a sheep or a human, but you need a lot of experience to hone it to a fine art. What we think happens is that they learn through the large amount of exposure they have to humans during the course of their lives to actually interpret the smiling and angry versions of the same individual's face. They can generalise from their familiar handler to any other human to see whether they're happy or angry as well.
Kat - How long have you been working with sheep for?
Keith - About twenty years.
Kat - So can you recognise sheep and tell the difference between individuals?
Keith - Let's put it this way: I'm a lot better at recognising sheep than most other people would be. But then I'm not the one who spends the largest amount of time with them. The people who spend four or five hours a day with them are really good at recognising sheep faces. However, it is a expertise based thing, just like recognising dogs or any other kind of species. Once we've been exposed to them for so long, we suddenly get very good at recognising the faces, although never as well as human faces.