The Expression of the Emotions in Man and Animals

[T]he young and the old of widely different races, both with man and animals, express the same state of mind by the same movements.

Even insects express anger, terror, jealousy, and love by their stridulation.

Through the principle of associated habit, the same movements of the face and eyes are practised, and can, indeed, hardly be avoided, whenever we know or believe that others are blaming, or too strongly praising, our moral conduct.