Which emotion links some people’s attitudes to the banking bonuses, journalists hacking the voicemail of Milly Dowler’s parents, our reaction to eating bitter lemons, the smell of Hydrogen Sulphate, and the Holocaust? The answer is disgust.

Disgust is a powerful emotion. Unlike other emotions, it exists in two areas. On one hand, we find things ‘physically’ disgusting, such as the smell of rotten eggs or the taste of bitter lemon. One the other hand, we can be ‘morally’ disgusted at the actions of others, such as in the case of the Milly Dowler phone hacking, or the greed of the banking industry. Disgust crosses the moral/physical divide like no other emotion and, as a result, it has recently become a hot topic within the academic world.

From the early modern period onwards, a number of thinkers have discussed disgust. The first was Thomas Hobbes. Hobbes claimed that “when the Endeavour [an action] is fromward [away from] something, it is generally called AVERSION”. Hobbes realised that these aversions were sometimes “born with men” and at other times “proceed from experience” and saw aversion, and its opposite, “appetite”, as the two great overriding emotions that explain human motivations.

Immanuel Kant was the first to look at disgust in its own right.  Kant took disgust as a primarily aesthetic emotion: ugliness in the extreme. He was also the first to describe the symptoms of disgust in a way we would recognise today. He knew that sensory experience was the key, and that disgust was connected to what he called the “lower class” senses: taste and smell. These senses, according to Kant, are linked primarily with pleasure through oral intake. Smell, more able to intimately sense what we are placing near our mouths than taste, acts as a trigger for physical reactions to disgust: facial grimacing, nausea and vomiting.

Charles Darwin was convinced that these reactions were inherent, describing the ‘plainly expressed’ disgust of babies as evidence for an evolved harm avoidance system, something many modern evolutionary psychologists agree with. Sigmund Freud tied Kantian ideas of oral fixation to the ‘sexual zones’. Freud linked our ability to walk upright with “raising our organ of smell form the ground,” taking it away from the “position of the genitals”. Freud believed that our genitals are beyond change and have “remained animal”, thus explaining the disgust felt for these areas.

After Freud, psychology took a back seat and disgust became mired in dirt – literally. In 1966 anthropologist Mary Douglas told us that “dirt is matter out of place.” Dirt, to Douglas, was any anomaly that defied “basic [social] assumptions”. The pursuit of cleanliness was, therefore, an attempt to restore order and put the matter back in its place, physically and morally. Douglas was a powerful influence, used, for example, by Simon Schama in The Embarrassment of Riches to explain the obsession with cleanliness in the art of the Dutch golden age. Many other studies on cleanliness and dirt followed, but disgust was all but ignored.

This was until Paul Rozin began to take an interest in Disgust in the 1980’s. Rozin’s ‘Hitler Pullover’ experiment – where people are asked if they are prepared to wear a pullover for a cash reward and are then, before donning the garment, informed it once belonged to Adolf Hitler – has become the stuff of legend. Rozin was the first to notice a link between disgust, essentialism (the idea that we attribute a soul-like ‘essence’ to certain objects) and sympathetic magic (the idea that this essence is transferable from person to object and vice versa). For many years Rozin pressed on with his research all but alone, but early in the last decade Professor Bruce Hood (of 2011 Christmas Lectures fame – see below, 17 minutes in) repeated many of Rozin’s experiments while investigating supernatural belief for his book SuperSense. This researched showed that ideas of essentialism and sympathetic magic, and so ideas of disgust, do exist in preschool children. Perhaps disgust is inherent after all?

Since this research, a number of books about disgust have been become popular. These include half a dozen books on the psychology of disgust as well as many in other disciplines, such as Carolyn Korsmeyer’s investigation into aesthetics in Savouring Disgust, the sociological work of William B. Miller’s Disgust, the phenomenological research of Aurel Kolnai’s On Disgust, Robert Rawdon Wilsons literary investigation The Hydra’s Tale, the Wellcome Collection’s Dirt exhibition and book, and more recently, Daniel Kelly’s superb interdisciplinary overview, Yuck! The Nature and Moral Significance of Disgust.  The importance of disgust, described by psychologist Susan B. Miller as “the gatekeeper emotion”, has been rediscovered; everyone wants a piece of it.

So what next for Disgust? Psychology is already taking great strides, but the other social sciences have great scope to expand our knowledge also investigating the social, cultural and even economic impact of disgust. With its new found energy, it is seems inevitable that academics in every discipline from philosophy to sociology will soon be taking the subject on.

I for my part, intend to contribute by to making early modern history just a little bit more disgusting.

Richard Firth-Godbehere is currently studying History and the History of Ideas at Goldsmiths, University of London and will be researching the Cultural and Intellectual History of Disgust in Early Modern Europe at Cambridge University from this autumn.