The Expression of the Emotions in Man and Animals in the laying out of the sandwalk, his "thinking path", at Down House in Kent in 1846. These aspects of Darwin's personal life are discussed in John Bowlby's (1990) psychoanalytic biography of Darwin. Darwin emphasises a shared human and animal ancestry in sharp contrast to the arguments deployed in Charles Bell's "Anatomy and Philosophy of Expression" (1824). Bell claimed that the facial muscles were divinely designed in order to express uniquely human feelings. Eager to stress the differences between human and animal communication, Bell wrote: "Expression is to the passions as language is to thought." In "The Expression", Darwin reformulates
Emotion in animals could be used to include all the animal kingdom as well as some plants. The second approach, mechanistic, requires an examination of the mechanisms that drive emotions and search for similarities in animals. The mechanistic approach is utilized extensively by Paul, Harding and Mendl. Recognizing the difficulty in studying emotion in non-verbal animals, Paul et al. demonstrate possible ways to better examine this. Observing the mechanisms that function in human emotion expression, Paul et al. suggest that concentration on similar mechanisms in animals can provide clear insights into the animal experience. They noted that in humans, cognitive biases vary according