When Prof Ramachandran introduces the curious Capgras delusion, in which the sufferer believes that close family members are impostors, he highlights how emotion reaches into parts of our brain processing that we may never have imagined previously. It is assumed that for such patients, although facial recognition is intact, a parallel system for registering the emotional meaning of the face had been damaged.

In fact, when patients are tested for the tell-tale physiological signals of emotions, such as slight changes in sweating detected by measuring skin resistance, these are found to be absent. This emotional response would normally occur for any of us when viewing faces showing emotional expressions, or faces of those we know well. Without them there is no emotional resonance, no sense of affiliation. In the Capgras delusion this absence of emotion is interpreted by the sufferer as evidence that this could not be someone close, despite the visual system contradicting this. It is significant that this conflict between the emotional and visual systems is resolved in favour of emotions rather than vision: feeling, rather than seeing, is believing. It seems that without emotion the familiar face is dismissed as an impostor.

It is widely acknowledged that much scientific progress is achieved by standing on the shoulders of the (scientific) giants that have come before us. So what did that true giant in evolutionary thinking, Charles Darwin, have to say about emotions? In his book ‘The expression of the emotions in man and animals’ (1872), Darwin (unsurprisingly) proposed that emotions and emotional expressions had become refined through natural selection and were therefore an advantage for our ancestors. However, he considered that emotions in (adult) humans were no longer very functional, we show expressions ‘though they may not ….. be of the least use’. For Darwin then, human emotions were somewhat akin to other vestigial organs or parts of the body, such as the appendix in the digestive system, a non-functional evolutionary hang over from times when they did have utility. This dismissal of emotions merely continued the tradition.

At least since Plato (375 BC), many Western thinkers have viewed emotions as impediments to rational thinking, as signs of immaturity or weakness, best set aside by upright, virtuous (and especially male) citizens. With this bad press, until recently, emotions have thus been afforded low priority for study, much less important than mental functions like perception, language, thinking, and learning. Giants’ shoulders have diverted attention away from recognising what was under our very noses; emotion impacts on almost all our brain processes.

Perhaps one of the contributing factors in its previous demise is that emotion is notoriously hard to define. This could be due, in part, to its many different facets. Emotion includes private internal feelings (conscious awareness), observable behaviours (including facial expressions and so-called ‘body language’), and physiological responses. Interest in emotion research has increased dramatically in the last 20 years, and once again scientists seek evolutionary functions for emotion.

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Content last updated: 01/04/2003

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