It would seem that Darwin’s theory of emotion deals more with the theory of the expression of emotion rather than a theory detailing the exact mechanisms of emotion. Darwin’s theory entails the underlying premise that emotional expressions necessitate the same emotional state across an entire species (Pinel, 2007). As with Darwin’s theory of natural selection, he believes that if a particular emotional expression is beneficial to a species that it will necessarily become more prevalent. He also believed that opposite emotional responses often signal the opposite emotional state (i.e. smile = happy and frown = sad).
Most people assume that feelings of emotion bring about emotional responses. These men hypothesized that through the pathways of the autonomic and somatic nervous system emotion-inducing sensory stimuli actually cause the experience of emotion in the brain, thereby stimulating emotional responses. For instance, the perception of a feared object might bring about physiological changes, such as walking fast through the woods, which in turn could bring about the feeling of fear; rather than the feeling of fear bringing about the act of walking faster in the woods.
Cannon and Bard believed that emotional expression and feelings of emotion run along mutually exclusive pathways with no direct relationship. This theory was based on the evidence that even when someone does not have an autonomic or somatic nervous system (i.e. broken spinal cord) they can still experience a full range of emotions. This theory dictates that emotional experience is totally independent of autonomic or somatic nervous system feedback.
This theory proposes that the various structures of the limbic system act on the action of the hypothalamus to produce emotional feelings and are experienced through the cortex. Papez offered a biological solution to emotion versus the aforementioned conceptual understandings of emotion. In his view emotion is controlled by the limbic system and expressed through the cortex.
Pinel, J. P. J. (2007). Basics of biopsychology. Boston, MA: Allyn and Bacon.