The Salem Witch Trials: the Devil’s Work or a Fungal Infection? 

By George Young

Few things carry the satisfaction of a historical mystery being put to rest by modern science. For well over three hundred years, the Salem Witch Trials have accumulated morbid fascination that extends far beyond the reaches of the Massachusetts city in which they took place.1 While the witchfinders were undeniably cruel sadists by night, they were excellent record-keepers by day. Their accounts of twisted executions and the ‘evidence’ upon which these deaths were based provide insights to modern-day biologists and historians researching the bloodshed.2

The witchfinders’ accounts were generally painted with a tint of superstition to justify the imposed sentence. These ranged from the mundane, like the presence of birthmarks, to occurrences which couldn’t be explained at the time due to the primitivity of available scientific knowledge. The latter of these is where this topic transgresses from history to biology – specifically, with the intriguing emergence of multiple accounts of possessed villagers.3 Supposed signs of a witch included crawling sensations under the skin, coupled with various other neurological symptoms and extreme nausea. At other times, witchfinder reports documented hallucinations of a disturbing nature, wasting of flesh which corrupted limbs and deep, insatiable itches. In the 17th century, this seemed to be the work of the Devil – but in the 21st century, a set of symptoms remarkably characteristic of ergotism.

Claviceps purpurea, a fungus whose optimum growth occurs inside grains like rye during specific weather conditions, is responsible for the production of alkaloids. These compounds are toxic to humans and known to cause ergot poisoning, which leads to ergotism with consistent exposure. Infected crops can be identified by the so-called ‘ergot bodies’ which look like blackened kernels – completely unbeknownst in 1600s America. In fact, there was no knowledge of C. purpurea or its effects at all, which is perhaps why it was so easy for rumours to spread, perpetuated by the equally ignorant witchfinders, that these ergotism symptoms were the sign of a witch. Of course, the theory that ergotism produced these symptoms that led to the Salem witch trials is just that – a theory. However, some evidence has been offered to support this argument.

It seems strange that a biologist would find themself in the realms of witches of the 1600s, but Professor Linnda Caporael recognised the link between the records of possessed villagers and the effects of this fungal pathogen. She took it upon herself to review various other historical records including the location of the villages in question and their weather patterns during the time of the witchfinder reports. C. purpurea (in its typical crop-infecting form) is most abundant around the onset of spring, especially after a fresh period of rain.4 Sure enough, there was a strong correlation between when/where the climate was optimum for C. purpurea growth and where reports emerged of possessed villagers.

This theory is not without criticism, however. In fact, it was received as something of a joke by many critics and historians. Notably, Stephen Nissenbaum, who is something of an expert regarding 17th century witches, had denounced Caporael’s claim. He reasonably highlighted the minimal chance that this scenario occurred only on these occasions and didn’t have an effect in other places on different years.5 Perhaps, then, it is misleading to describe this mystery as ‘put to rest’, given the controversy that Caporael has faced. True or not, the concept of a fungal pathogen giving rise to such a sinister sequence of events, whose effects have resonated throughout history, makes for a compelling story at the very least.


1) Blumberg J. A brief history of the Salem witch trials. 2007; 23 .

2) Le Beau BF. The story of the Salem witch trials. : Routledge; 2016. 

3) Murrin JM. Coming to terms with the Salem witch trials. Proceedings of the American Antiquarian Society, : American Antiquarian Society.; 2000. pp. 309. 

4) Tudzynski P, Scheffer J. Claviceps purpurea: molecular aspects of a unique pathogenic lifestyle. Molecular Plant Pathology. 2004; 5 (5): 377-388. 

5) Spanos NP, Gottlieb J. Ergotism and the Salem Village Witch Trials: Records of the events of 1692 do not support the hypothesis that ergot poisoning was involved. Science. 1976; 194 (4272): 1390-1394. 

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