Does Disgust Protect Us from Pathogens?

Blog by Philippa Nicole Barr

Barr, Philippa Nicole - Does Disgust Protect Us from Pathogens CoverWe have all heard the provocative discussions about turning protein-rich insects into a viable, global food source for humans and animals.1 Yet the idea of eating them generates disgust or approval, depending on where in the world they are being served. What does this variable response imply for theories that disgust protects us from pathogens?

For the past two decades, the idea that disgust evolved to support disease prevention has generated controversy. Pathogen avoidance theory maintains that human self-preservation depends on avoiding, sublimating, or destroying microbes. Yet the range of situations and circumstances provoking disgust is much wider than mere pathogen avoidance, and—importantly—pathogenic objects do not always trigger disgust. In my recent book with Cambridge Elements, Uncertainty and Emotion in the 1900 Sydney Plague, I argue that knowledge informs our judgement of what is repulsive or acceptable.2 Both historical evidence and social theory challenges the straightforward assumption that disgust serves as a biological shield. The role of disgust extends beyond mere pathogen avoidance to regulate cultural and historical ideas of contamination and disorder.

In the late nineteenth and early twentieth centuries, the world grappled with the third global plague pandemic. It was one of the first global pandemics to benefit from the new science of bacteriology. Yet even after the bacteria that caused the plague was identified in the late nineteenth century, uncertainty remained about how the disease was transmitted from rats to humans. When the plague arrived in Sydney in 1900, newspaper reports highlighted a lack of clarity on how the disease spread, fuelling confused debates about how to manage the outbreak and prevent plague spread.3

City of Sydney, Print - Terrace houses in Wattle Street Pyrmont, circa 1900 (01/01/1900 - 31/12/1900), [A-00036137]. City of Sydney Archives,
City of Sydney – Terrace houses in Wattle Street Pyrmont, circa 1900 City of Sydney Archives,

During the initial outbreak, many officials and laypeople in Sydney believed in miasmatic theories of disease transmission, which held that disease spread through bad air or unpleasant smells. In this context, foul air was not just repulsive but a source of disease, whereas air that was fresh or transformed was regarded as having healing or defensive properties.

The first plague outbreak in Sydney involved a comprehensive campaign to fumigate streets, ships, and sewers. Local residents also tried to transform the air around them. For example, the widespread belief that onions could purify the body and the air by capturing germs caused people to place sliced onions beside the deceased to capture germs from the air. The Evening News reported a generalised panic of onion buying; however, some customers rejected the Victorian brown Spanish bulb, which was supposed to be “too mild” to prevent against plague.4

Smoking spiked during the plague because people believed it was a “germ killer.”5 The Collector of Customs even permitted smoking inside various parts of the Customs House at Circular Quay.6 Camphor was another popular air purification method. As an extra precaution, workers near infected harbour areas carried camphor with them. Like onions, camphor became so popular that its price surged.7

The belief that some odours were noxious and others were protective illustrates the historical and cultural plasticity of disgust objects. Rather than recoiling from the intense odours of tobacco or camphor, people reinterpreted pungent or acrid smells as fortifying due to the lingering belief in miasmatic theories of disease causation. Disgust, therefore, can be flexible and is shaped by culture, knowledge, and experience, which change over time.

The traditional model of disgust assumes it is a universal affective process, not only in humans, but in all mammals, helping to “sense conditions that need to be avoided in order to prevent disease.”8 Whilst this is an interesting idea, there are strong arguments against it. If emotions are universally oriented around the goal of pathogen avoidance, then our responses and behaviours should be consistent in a range of contexts. Humans undertake many activities that can easily transmit bacteria or infections but do not elicit a disgust response.9 As we have seen with the examples of wearing camphor, carrying onions, and smoking, many pathogen avoidance behaviours do not, in fact, avert pathogens. They manage emotions.

In 1966, Mary Douglas argued that disgust as “pathogen avoidance” is an overly simplistic idea, noting that it fails to capture the aesthetic and spiritual aspects of hygienic practices.10 In a later study, Rozin and Fallon discuss how reactions to noxious stimuli can extend to benign or even nutritious food, depending on history or context, which suggests that our perceptions of contamination are not always aligned with actual harm.11 Clearly we associate some foods, such as insects, with contamination or disgust, even if they could be beneficial. Rottman et al. and Greenhough et al. also challenge the strict pathogen avoidance model of disgust, noting that the distinction between harmful pathogens and beneficial bacteria is not always clear, and sometimes avoiding pathogens can be counterproductive.12

Not all the people, places and objects that triggered disgust in 1900 were pathogenic. As in other instances of uncertainty and rapid change, Sydney’s medical professionals and public officials could not fully identify the threat or always convince the public of their best guesses. This history shows us that our emotional responses do not simply protect us from pathogens but embody cultural ideas of what is threatening or safe. Perhaps one day insects will be on all our menus?

Uncertainty and Emotion in the 1900 Sydney Plague is free to download from Cambridge University Press between April 29 and May 13, 2024.


Philippa Nicole Barr holds a research position in the School of History at Australian National University and a professional role in education innovation at Western Sydney University. Uncertainty and Emotion in the 1900 Sydney Plague is her first book.


[1] See, for example, David Fickling, “Insect-Farming Could Lead to Eating Even More Meat,” editorial, Bloomberg News, March 4, 2024,

[2] Philippa Nicole Barr, Uncertainty and Emotion in the 1900 Sydney Plague, Elements in Histories of Emotions and the Senses (Cambridge: Cambridge University Press, 2024). The Cambridge Elements series by Cambridge University Press consists of short format peer-reviewed scholarly and scientific research.

[3] “Citizens’ Vigilance Committee,” Sydney Morning Herald, December 15, 1900, 10,

[4] “Parramatta’s Sanitary Condition,” Evening News, March 22, 1900, 6,

[5] “The Plague,” Evening News, March 22, 1900, 6,

[6] Peter Curson and Kevin McCracken, Plague in Sydney: The Anatomy of an Epidemic (Kensington: New South Wales University Press, 1989), 184.

[7] “The Plague,” 6.

[8] Jaak Panksepp, “Criteria for Basic Emotions: Is Disgust a Primary ‘Emotion’?” Cognition & Emotion 21, no. 8 (December 2007): 1826,

[9] Joshua M. Tybur, Catherine Molho, and Daniel Balliet, “Moralized Disgust versus Disgusting Immorality: An Adaptationist Perspective,” in The Moral Psychology of Disgust, edited by Nina Strohminger and Victor Kumar (London: Rowman & Littlefield International, 2020), 12.

[10] Mary Douglas, Purity and Danger: An Analysis of Concepts of Pollution and Taboo (London: Routledge & Kegan Paul, 1966), 29.

[11] Paul Rozin and April E. Fallon, “A Perspective on Disgust,” Psychological Review 94, no. 1 (1987): 22,

[12] Joshua Rottman, Jasmine M. DeJesus, and Emily Gerdin, “The Social Origins of Disgust,” in The Moral Psychology of Disgust, edited by Nina Strohminger and Victor Kumar (London: Rowman & Littlefield International, 2020), 29; Beth Greenhough et al., “Unsettling Antibiosis: How Might Interdisciplinary Researchers Generate a Feeling for the Microbiome and to What Effect?” Palgrave Communications 4, article no. 149 (2018): 1,

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