The Expression of the Emotions in Man and Animals posited the theory that animals express emotion in a similar way to humans.

BBC: Friday 11 September: Darwin special

It's commanding as comic-book art in motion, convincing as the luridly mythic -- and therefore authentically adolescent -- expression of buried emotions.

WSJ: The 'Bourne' Identity Crisis

Where there was any change in the dogs' expression, it was seen to be a subsequent reflection of the human's emotions.

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