Do Sheep Recognize Faces?

Rosa Bonheur -- Sheep studies in oil

Scientists studying the brains of sheep are learning a lot about their abilities at face recognition:
1. As a social species, sheep recognize many other sheep individuals, and retain memories of those faces for years.
2. When they look at other sheep faces, sheep are aware of expressions of negative emotions such as stress or anxiety, and when given the choice, they prefer the calm face. They also prefer a calm human face.
3. They're particularly aware of ear position and amount of sclera (the whites of the eyes) visible, both of which are strong markers of emotion in sheep.
4. Unlike humans, sheep have special populations of brain cells tuned to recognizing horns and assessing their size, since horns are markers of gender and dominance.
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Summary of findings in this paper: Behavioural and neurophysiological evidence for face identity and face emotion processing in animals
Andrew J Tate, Hanno Fischer, Andrea E Leigh, and Keith M Kendrick*